diff options
| author | Yuval Adam <yuv.adm@gmail.com> | 2014-03-16 14:40:16 +0200 |
|---|---|---|
| committer | Yuval Adam <yuv.adm@gmail.com> | 2014-03-16 14:40:16 +0200 |
| commit | 7f4da522479c0f00126219f0c23b804c3a93d7a6 (patch) | |
| tree | 59239ebbee0a424422d3a6653e55c4fd803dc0ad /driverlib/can.c | |
| parent | 413719367418ca7485f449d7bbae680ed75ee46d (diff) | |
Add driver lib for projects which require it
Diffstat (limited to 'driverlib/can.c')
| -rw-r--r-- | driverlib/can.c | 2117 |
1 files changed, 2117 insertions, 0 deletions
diff --git a/driverlib/can.c b/driverlib/can.c new file mode 100644 index 0000000..1515a75 --- /dev/null +++ b/driverlib/can.c @@ -0,0 +1,2117 @@ +//*****************************************************************************
+//
+// can.c - Driver for the CAN module.
+//
+// Copyright (c) 2006-2014 Texas Instruments Incorporated. All rights reserved.
+// Software License Agreement
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+// Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//
+// Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the
+// distribution.
+//
+// Neither the name of Texas Instruments Incorporated nor the names of
+// its contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// This is part of revision 2.1.0.12573 of the Tiva Peripheral Driver Library.
+//
+//*****************************************************************************
+
+//*****************************************************************************
+//
+//! \addtogroup can_api
+//! @{
+//
+//*****************************************************************************
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "inc/hw_can.h"
+#include "inc/hw_ints.h"
+#include "inc/hw_nvic.h"
+#include "inc/hw_memmap.h"
+#include "inc/hw_sysctl.h"
+#include "inc/hw_types.h"
+#include "driverlib/can.h"
+#include "driverlib/debug.h"
+#include "driverlib/interrupt.h"
+
+//*****************************************************************************
+//
+// This is the maximum number that can be stored as an 11bit Message
+// identifier.
+//
+//*****************************************************************************
+#define CAN_MAX_11BIT_MSG_ID 0x7ff
+
+//*****************************************************************************
+//
+// The maximum CAN bit timing divisor is 19.
+//
+//*****************************************************************************
+#define CAN_MAX_BIT_DIVISOR 19
+
+//*****************************************************************************
+//
+// The minimum CAN bit timing divisor is 4.
+//
+//*****************************************************************************
+#define CAN_MIN_BIT_DIVISOR 4
+
+//*****************************************************************************
+//
+// The maximum CAN pre-divisor is 1024.
+//
+//*****************************************************************************
+#define CAN_MAX_PRE_DIVISOR 1024
+
+//*****************************************************************************
+//
+// The minimum CAN pre-divisor is 1.
+//
+//*****************************************************************************
+#define CAN_MIN_PRE_DIVISOR 1
+
+//*****************************************************************************
+//
+// Converts a set of CAN bit timing values into the value that needs to be
+// programmed into the CAN_BIT register to achieve those timings.
+//
+//*****************************************************************************
+#define CAN_BIT_VALUE(seg1, seg2, sjw) \
+ ((((seg1 - 1) << CAN_BIT_TSEG1_S) & \
+ CAN_BIT_TSEG1_M) | \
+ (((seg2 - 1) << CAN_BIT_TSEG2_S) & \
+ CAN_BIT_TSEG2_M) | \
+ (((sjw - 1) << CAN_BIT_SJW_S) & \
+ CAN_BIT_SJW_M))
+
+//*****************************************************************************
+//
+// This table is used by the CANBitRateSet() API as the register defaults for
+// the bit timing values.
+//
+//*****************************************************************************
+static const uint16_t g_ui16CANBitValues[] =
+{
+ CAN_BIT_VALUE(2, 1, 1), // 4 clocks/bit
+ CAN_BIT_VALUE(3, 1, 1), // 5 clocks/bit
+ CAN_BIT_VALUE(3, 2, 2), // 6 clocks/bit
+ CAN_BIT_VALUE(4, 2, 2), // 7 clocks/bit
+ CAN_BIT_VALUE(4, 3, 3), // 8 clocks/bit
+ CAN_BIT_VALUE(5, 3, 3), // 9 clocks/bit
+ CAN_BIT_VALUE(5, 4, 4), // 10 clocks/bit
+ CAN_BIT_VALUE(6, 4, 4), // 11 clocks/bit
+ CAN_BIT_VALUE(6, 5, 4), // 12 clocks/bit
+ CAN_BIT_VALUE(7, 5, 4), // 13 clocks/bit
+ CAN_BIT_VALUE(7, 6, 4), // 14 clocks/bit
+ CAN_BIT_VALUE(8, 6, 4), // 15 clocks/bit
+ CAN_BIT_VALUE(8, 7, 4), // 16 clocks/bit
+ CAN_BIT_VALUE(9, 7, 4), // 17 clocks/bit
+ CAN_BIT_VALUE(9, 8, 4), // 18 clocks/bit
+ CAN_BIT_VALUE(10, 8, 4) // 19 clocks/bit
+};
+
+//*****************************************************************************
+//
+//! \internal
+//! Checks a CAN base address.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//!
+//! This function determines if a CAN controller base address is valid.
+//!
+//! \return Returns \b true if the base address is valid and \b false
+//! otherwise.
+//
+//*****************************************************************************
+#ifdef DEBUG
+static bool
+_CANBaseValid(uint32_t ui32Base)
+{
+ return((ui32Base == CAN0_BASE) || (ui32Base == CAN1_BASE));
+}
+#endif
+
+//*****************************************************************************
+//
+//! Returns the CAN controller interrupt number.
+//!
+//! \param ui32Base is the base address of the selected CAN controller
+//!
+//! This function returns the interrupt number for the CAN module with the base
+//! address passed in the \e ui32Base parameter.
+//!
+//! \return Returns a CAN interrupt number or 0 if the interrupt does not
+//! exist.
+//
+//*****************************************************************************
+static uint_fast8_t
+_CANIntNumberGet(uint32_t ui32Base)
+{
+ uint_fast8_t ui8Int;
+
+ ASSERT((ui32Base == CAN0_BASE) || (ui32Base == CAN1_BASE));
+
+ ui8Int = 0;
+
+ //
+ // Find the valid interrupt number for this CAN controller.
+ //
+ if(CLASS_IS_TM4C123)
+ {
+ if(ui32Base == CAN0_BASE)
+ {
+ ui8Int = INT_CAN0_TM4C123;
+ }
+ else if(ui32Base == CAN1_BASE)
+ {
+ ui8Int = INT_CAN1_TM4C123;
+ }
+ }
+ else if(CLASS_IS_TM4C129)
+ {
+ if(ui32Base == CAN0_BASE)
+ {
+ ui8Int = INT_CAN0_TM4C129;
+ }
+ else if(ui32Base == CAN1_BASE)
+ {
+ ui8Int = INT_CAN1_TM4C129;
+ }
+ }
+
+ return(ui8Int);
+}
+
+//*****************************************************************************
+//
+//! \internal
+//! Copies data from a buffer to the CAN Data registers.
+//!
+//! \param pui8Data is a pointer to the data to be written out to the CAN
+//! controller's data registers.
+//! \param pui32Register is an uint32_t pointer to the first register of the
+//! CAN controller's data registers. For example, in order to use the IF1
+//! register set on CAN controller 0, the value would be: \b CAN0_BASE \b +
+//! \b CAN_O_IF1DA1.
+//! \param iSize is the number of bytes to copy into the CAN controller.
+//!
+//! This function takes the steps necessary to copy data from a contiguous
+//! buffer in memory into the non-contiguous data registers used by the CAN
+//! controller. This function is rarely used outside of the CANMessageSet()
+//! function.
+//!
+//! \return None.
+//
+//*****************************************************************************
+static void
+_CANDataRegWrite(uint8_t *pui8Data, uint32_t *pui32Register, uint32_t ui32Size)
+{
+ uint32_t ui32Idx, ui32Value;
+
+ //
+ // Loop always copies 1 or 2 bytes per iteration.
+ //
+ for(ui32Idx = 0; ui32Idx < ui32Size; )
+ {
+ //
+ // Write out the data 16 bits at a time since this is how the registers
+ // are aligned in memory.
+ //
+ ui32Value = pui8Data[ui32Idx++];
+
+ //
+ // Only write the second byte if needed otherwise the value is zero.
+ //
+ if(ui32Idx < ui32Size)
+ {
+ ui32Value |= (pui8Data[ui32Idx++] << 8);
+ }
+
+ HWREG(pui32Register++) = ui32Value;
+ }
+}
+
+//*****************************************************************************
+//
+//! \internal
+//! Copies data from a buffer to the CAN Data registers.
+//!
+//! \param pui8Data is a pointer to the location to store the data read from
+//! the CAN controller's data registers.
+//! \param pui32Register is an uint32_t pointer to the first register of the
+//! CAN controller's data registers. For example, in order to use the IF1
+//! register set on CAN controller 1, the value would be: \b CAN0_BASE \b +
+//! \b CAN_O_IF1DA1.
+//! \param iSize is the number of bytes to copy from the CAN controller.
+//!
+//! This function takes the steps necessary to copy data to a contiguous buffer
+//! in memory from the non-contiguous data registers used by the CAN
+//! controller. This function is rarely used outside of the CANMessageGet()
+//! function.
+//!
+//! \return None.
+//
+//*****************************************************************************
+static void
+_CANDataRegRead(uint8_t *pui8Data, uint32_t *pui32Register, uint32_t ui32Size)
+{
+ uint32_t ui32Idx, ui32Value;
+
+ //
+ // Loop always copies 1 or 2 bytes per iteration.
+ //
+ for(ui32Idx = 0; ui32Idx < ui32Size; )
+ {
+ //
+ // Read out the data 16 bits at a time since this is how the registers
+ // are aligned in memory.
+ //
+ ui32Value = HWREG(pui32Register++);
+
+ //
+ // Store the first byte.
+ //
+ pui8Data[ui32Idx++] = (uint8_t)ui32Value;
+
+ //
+ // Only read the second byte if needed.
+ //
+ if(ui32Idx < ui32Size)
+ {
+ pui8Data[ui32Idx++] = (uint8_t)(ui32Value >> 8);
+ }
+ }
+}
+
+//*****************************************************************************
+//
+//! Initializes the CAN controller after reset.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//!
+//! After reset, the CAN controller is left in the disabled state. However,
+//! the memory used for message objects contains undefined values and must be
+//! cleared prior to enabling the CAN controller the first time. This prevents
+//! unwanted transmission or reception of data before the message objects are
+//! configured. This function must be called before enabling the controller
+//! the first time.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANInit(uint32_t ui32Base)
+{
+ uint32_t ui32Msg;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // Place CAN controller in init state, regardless of previous state. This
+ // puts controller in idle, and allow the message object RAM to be
+ // programmed.
+ //
+ HWREG(ui32Base + CAN_O_CTL) = CAN_CTL_INIT;
+
+ //
+ // Wait for busy bit to clear
+ //
+ while(HWREG(ui32Base + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // Clear the message value bit in the arbitration register. This indicates
+ // the message is not valid and is a "safe" condition to leave the message
+ // object. The same arb reg is used to program all the message objects.
+ //
+ HWREG(ui32Base + CAN_O_IF1CMSK) = (CAN_IF1CMSK_WRNRD | CAN_IF1CMSK_ARB |
+ CAN_IF1CMSK_CONTROL);
+ HWREG(ui32Base + CAN_O_IF1ARB2) = 0;
+ HWREG(ui32Base + CAN_O_IF1MCTL) = 0;
+
+ //
+ // Loop through to program all 32 message objects
+ //
+ for(ui32Msg = 1; ui32Msg <= 32; ui32Msg++)
+ {
+ //
+ // Wait for busy bit to clear
+ //
+ while(HWREG(ui32Base + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // Initiate programming the message object
+ //
+ HWREG(ui32Base + CAN_O_IF1CRQ) = ui32Msg;
+ }
+
+ //
+ // Make sure that the interrupt and new data flags are updated for the
+ // message objects.
+ //
+ HWREG(ui32Base + CAN_O_IF1CMSK) = (CAN_IF1CMSK_NEWDAT |
+ CAN_IF1CMSK_CLRINTPND);
+
+ //
+ // Loop through to program all 32 message objects
+ //
+ for(ui32Msg = 1; ui32Msg <= 32; ui32Msg++)
+ {
+ //
+ // Wait for busy bit to clear.
+ //
+ while(HWREG(ui32Base + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // Initiate programming the message object
+ //
+ HWREG(ui32Base + CAN_O_IF1CRQ) = ui32Msg;
+ }
+
+ //
+ // Acknowledge any pending status interrupts.
+ //
+ HWREG(ui32Base + CAN_O_STS);
+}
+
+//*****************************************************************************
+//
+//! Enables the CAN controller.
+//!
+//! \param ui32Base is the base address of the CAN controller to enable.
+//!
+//! Enables the CAN controller for message processing. Once enabled, the
+//! controller automatically transmits any pending frames, and processes any
+//! received frames. The controller can be stopped by calling CANDisable().
+//! Prior to calling CANEnable(), CANInit() must have been called to
+//! initialize the controller and the CAN bus clock must be configured by
+//! calling CANBitTimingSet().
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANEnable(uint32_t ui32Base)
+{
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // Clear the init bit in the control register.
+ //
+ HWREG(ui32Base + CAN_O_CTL) &= ~CAN_CTL_INIT;
+}
+
+//*****************************************************************************
+//
+//! Disables the CAN controller.
+//!
+//! \param ui32Base is the base address of the CAN controller to disable.
+//!
+//! Disables the CAN controller for message processing. When disabled, the
+//! controller no longer automatically processes data on the CAN bus. The
+//! controller can be restarted by calling CANEnable(). The state of the CAN
+//! controller and the message objects in the controller are left as they were
+//! before this call was made.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANDisable(uint32_t ui32Base)
+{
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // Set the init bit in the control register.
+ //
+ HWREG(ui32Base + CAN_O_CTL) |= CAN_CTL_INIT;
+}
+
+//*****************************************************************************
+//
+//! Reads the current settings for the CAN controller bit timing.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param psClkParms is a pointer to a structure to hold the timing
+//! parameters.
+//!
+//! This function reads the current configuration of the CAN controller bit
+//! clock timing and stores the resulting information in the structure
+//! supplied by the caller. Refer to CANBitTimingSet() for the meaning of the
+//! values that are returned in the structure pointed to by \e psClkParms.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANBitTimingGet(uint32_t ui32Base, tCANBitClkParms *psClkParms)
+{
+ uint32_t ui32BitReg;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT(psClkParms);
+
+ //
+ // Read out all the bit timing values from the CAN controller registers.
+ //
+ ui32BitReg = HWREG(ui32Base + CAN_O_BIT);
+
+ //
+ // Set the phase 2 segment.
+ //
+ psClkParms->ui32Phase2Seg =
+ ((ui32BitReg & CAN_BIT_TSEG2_M) >> CAN_BIT_TSEG2_S) + 1;
+
+ //
+ // Set the phase 1 segment.
+ //
+ psClkParms->ui32SyncPropPhase1Seg =
+ ((ui32BitReg & CAN_BIT_TSEG1_M) >> CAN_BIT_TSEG1_S) + 1;
+
+ //
+ // Set the synchronous jump width.
+ //
+ psClkParms->ui32SJW = ((ui32BitReg & CAN_BIT_SJW_M) >> CAN_BIT_SJW_S) + 1;
+
+ //
+ // Set the pre-divider for the CAN bus bit clock.
+ //
+ psClkParms->ui32QuantumPrescaler =
+ ((ui32BitReg & CAN_BIT_BRP_M) |
+ ((HWREG(ui32Base + CAN_O_BRPE) & CAN_BRPE_BRPE_M) << 6)) + 1;
+}
+
+//*****************************************************************************
+//
+//! Sets the CAN bit timing values to a nominal setting based on a desired
+//! bit rate.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param ui32SourceClock is the system clock for the device in Hz.
+//! \param ui32BitRate is the desired bit rate.
+//!
+//! This function sets the CAN bit timing for the bit rate passed in the
+//! \e ui32BitRate parameter based on the \e ui32SourceClock parameter.
+//! Because the CAN clock is based off of the system clock, the calling
+//! function must pass in the source clock rate either by retrieving it from
+//! SysCtlClockGet() or using a specific value in Hz. The CAN bit timing is
+//! calculated assuming a minimal amount of propagation delay, which works for
+//! most cases where the network length is short. If tighter timing
+//! requirements or longer network lengths are needed, then the
+//! CANBitTimingSet() function is available for full customization of all of
+//! the CAN bit timing values. Because not all bit rates can be matched
+//! exactly, the bit rate is set to the value closest to the desired bit rate
+//! without being higher than the \e ui32BitRate value.
+//!
+//! \note On some devices the source clock is fixed at 8MHz so the
+//! \e ui32SourceClock must be set to 8000000.
+//!
+//! \return This function returns the bit rate that the CAN controller was
+//! configured to use or it returns 0 to indicate that the bit rate was not
+//! changed because the requested bit rate was not valid.
+//!
+//*****************************************************************************
+uint32_t
+CANBitRateSet(uint32_t ui32Base, uint32_t ui32SourceClock,
+ uint32_t ui32BitRate)
+{
+ uint32_t ui32DesiredRatio;
+ uint32_t ui32CANBits;
+ uint32_t ui32PreDivide;
+ uint32_t ui32RegValue;
+ uint16_t ui16CANCTL;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT(ui32SourceClock);
+ ASSERT(ui32BitRate);
+
+ //
+ // Calculate the desired clock rate.
+ //
+ ui32DesiredRatio = ui32SourceClock / ui32BitRate;
+
+ //
+ // Make sure that the ratio of CAN bit rate to processor clock is not too
+ // small or too large.
+ //
+ ASSERT(ui32DesiredRatio <= (CAN_MAX_PRE_DIVISOR * CAN_MAX_BIT_DIVISOR));
+ ASSERT(ui32DesiredRatio >= (CAN_MIN_PRE_DIVISOR * CAN_MIN_BIT_DIVISOR));
+
+ //
+ // Make sure that the Desired Ratio is not too large. This enforces the
+ // requirement that the bit rate is larger than requested.
+ //
+ if((ui32SourceClock / ui32DesiredRatio) > ui32BitRate)
+ {
+ ui32DesiredRatio += 1;
+ }
+
+ //
+ // Check all possible values to find a matching value.
+ //
+ while(ui32DesiredRatio <= (CAN_MAX_PRE_DIVISOR * CAN_MAX_BIT_DIVISOR))
+ {
+ //
+ // Loop through all possible CAN bit divisors.
+ //
+ for(ui32CANBits = CAN_MAX_BIT_DIVISOR;
+ ui32CANBits >= CAN_MIN_BIT_DIVISOR; ui32CANBits--)
+ {
+ //
+ // For a given CAN bit divisor save the pre divisor.
+ //
+ ui32PreDivide = ui32DesiredRatio / ui32CANBits;
+
+ //
+ // If the calculated divisors match the desired clock ratio then
+ // return these bit rate and set the CAN bit timing.
+ //
+ if((ui32PreDivide * ui32CANBits) == ui32DesiredRatio)
+ {
+ //
+ // Start building the bit timing value by adding the bit timing
+ // in time quanta.
+ //
+ ui32RegValue = g_ui16CANBitValues[ui32CANBits -
+ CAN_MIN_BIT_DIVISOR];
+
+ //
+ // To set the bit timing register, the controller must be
+ // placed in init mode (if not already), and also configuration
+ // change bit enabled. The state of the register must be
+ // saved so it can be restored.
+ //
+ ui16CANCTL = HWREG(ui32Base + CAN_O_CTL);
+ HWREG(ui32Base + CAN_O_CTL) = ui16CANCTL | CAN_CTL_INIT |
+ CAN_CTL_CCE;
+
+ //
+ // Now add in the pre-scalar on the bit rate.
+ //
+ ui32RegValue |= ((ui32PreDivide - 1) & CAN_BIT_BRP_M);
+
+ //
+ // Set the clock bits in the and the lower bits of the
+ // pre-scalar.
+ //
+ HWREG(ui32Base + CAN_O_BIT) = ui32RegValue;
+
+ //
+ // Set the divider upper bits in the extension register.
+ //
+ HWREG(ui32Base + CAN_O_BRPE) = ((ui32PreDivide - 1) >> 6) &
+ CAN_BRPE_BRPE_M;
+
+ //
+ // Restore the saved CAN Control register.
+ //
+ HWREG(ui32Base + CAN_O_CTL) = ui16CANCTL;
+
+ //
+ // Return the computed bit rate.
+ //
+ return(ui32SourceClock / (ui32PreDivide * ui32CANBits));
+ }
+ }
+
+ //
+ // Move the divisor up one and look again. Only in rare cases are
+ // more than 2 loops required to find the value.
+ //
+ ui32DesiredRatio++;
+ }
+
+ //
+ // A valid combination could not be found, so return 0 to indicate that the
+ // bit rate was not changed.
+ //
+ return(0);
+}
+
+//*****************************************************************************
+//
+//! Configures the CAN controller bit timing.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param psClkParms points to the structure with the clock parameters.
+//!
+//! Configures the various timing parameters for the CAN bus bit timing:
+//! Propagation segment, Phase Buffer 1 segment, Phase Buffer 2 segment, and
+//! the Synchronization Jump Width. The values for Propagation and Phase
+//! Buffer 1 segments are derived from the combination
+//! \e psClkParms->ui32SyncPropPhase1Seg parameter. Phase Buffer 2 is
+//! determined from the \e psClkParms->ui32Phase2Seg parameter. These two
+//! parameters, along with \e psClkParms->ui32SJW are based in units of bit
+//! time quanta. The actual quantum time is determined by the
+//! \e psClkParms->ui32QuantumPrescaler value, which specifies the divisor for
+//! the CAN module clock.
+//!
+//! The total bit time, in quanta, is the sum of the two Seg parameters,
+//! as follows:
+//!
+//! bit_time_q = ui32SyncPropPhase1Seg + ui32Phase2Seg + 1
+//!
+//! Note that the Sync_Seg is always one quantum in duration, and is added
+//! to derive the correct duration of Prop_Seg and Phase1_Seg.
+//!
+//! The equation to determine the actual bit rate is as follows:
+//!
+//! CAN Clock /
+//! ((\e ui32SyncPropPhase1Seg + \e ui32Phase2Seg + 1) *
+//! (\e ui32QuantumPrescaler))
+//!
+//! Thus with \e ui32SyncPropPhase1Seg = 4, \e ui32Phase2Seg = 1,
+//! \e ui32QuantumPrescaler = 2 and an 8 MHz CAN clock, the bit rate is
+//! (8 MHz) / ((5 + 2 + 1) * 2) or 500 Kbit/sec.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANBitTimingSet(uint32_t ui32Base, tCANBitClkParms *psClkParms)
+{
+ uint32_t ui32BitReg, ui32SavedInit;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT(psClkParms);
+
+ //
+ // The phase 1 segment must be in the range from 2 to 16.
+ //
+ ASSERT((psClkParms->ui32SyncPropPhase1Seg >= 2) &&
+ (psClkParms->ui32SyncPropPhase1Seg <= 16));
+
+ //
+ // The phase 2 segment must be in the range from 1 to 8.
+ //
+ ASSERT((psClkParms->ui32Phase2Seg >= 1) &&
+ (psClkParms->ui32Phase2Seg <= 8));
+
+ //
+ // The synchronous jump windows must be in the range from 1 to 4.
+ //
+ ASSERT((psClkParms->ui32SJW >= 1) && (psClkParms->ui32SJW <= 4));
+
+ //
+ // The CAN clock pre-divider must be in the range from 1 to 1024.
+ //
+ ASSERT((psClkParms->ui32QuantumPrescaler <= 1024) &&
+ (psClkParms->ui32QuantumPrescaler >= 1));
+
+ //
+ // To set the bit timing register, the controller must be placed in init
+ // mode (if not already), and also configuration change bit enabled. State
+ // of the init bit must be saved so it can be restored at the end.
+ //
+ ui32SavedInit = HWREG(ui32Base + CAN_O_CTL);
+ HWREG(ui32Base + CAN_O_CTL) = ui32SavedInit | CAN_CTL_INIT | CAN_CTL_CCE;
+
+ //
+ // Set the bit fields of the bit timing register according to the parms.
+ //
+ ui32BitReg = (((psClkParms->ui32Phase2Seg - 1) << CAN_BIT_TSEG2_S) &
+ CAN_BIT_TSEG2_M);
+ ui32BitReg |= (((psClkParms->ui32SyncPropPhase1Seg - 1) <<
+ CAN_BIT_TSEG1_S) & CAN_BIT_TSEG1_M);
+ ui32BitReg |= ((psClkParms->ui32SJW - 1) << CAN_BIT_SJW_S) & CAN_BIT_SJW_M;
+ ui32BitReg |= (psClkParms->ui32QuantumPrescaler - 1) & CAN_BIT_BRP_M;
+ HWREG(ui32Base + CAN_O_BIT) = ui32BitReg;
+
+ //
+ // Set the divider upper bits in the extension register.
+ //
+ HWREG(ui32Base + CAN_O_BRPE) =
+ ((psClkParms->ui32QuantumPrescaler - 1) >> 6) & CAN_BRPE_BRPE_M;
+
+ //
+ // Clear the config change bit, and restore the init bit.
+ //
+ ui32SavedInit &= ~CAN_CTL_CCE;
+
+ //
+ // If Init was not set before, then clear it.
+ //
+ if(ui32SavedInit & CAN_CTL_INIT)
+ {
+ ui32SavedInit &= ~CAN_CTL_INIT;
+ }
+
+ HWREG(ui32Base + CAN_O_CTL) = ui32SavedInit;
+}
+
+//*****************************************************************************
+//
+//! Registers an interrupt handler for the CAN controller.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param pfnHandler is a pointer to the function to be called when the
+//! enabled CAN interrupts occur.
+//!
+//! This function registers the interrupt handler in the interrupt vector
+//! table, and enables CAN interrupts on the interrupt controller; specific CAN
+//! interrupt sources must be enabled using CANIntEnable(). The interrupt
+//! handler being registered must clear the source of the interrupt using
+//! CANIntClear().
+//!
+//! If the application is using a static interrupt vector table stored in
+//! flash, then it is not necessary to register the interrupt handler this way.
+//! Instead, IntEnable() is used to enable CAN interrupts on the
+//! interrupt controller.
+//!
+//! \sa IntRegister() for important information about registering interrupt
+//! handlers.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANIntRegister(uint32_t ui32Base, void (*pfnHandler)(void))
+{
+ uint_fast8_t ui8IntNumber;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // Get the actual interrupt number for this CAN controller.
+ //
+ ui8IntNumber = _CANIntNumberGet(ui32Base);
+ ASSERT(ui8IntNumber != 0);
+
+ //
+ // Register the interrupt handler.
+ //
+ IntRegister(ui8IntNumber, pfnHandler);
+
+ //
+ // Enable the Ethernet interrupt.
+ //
+ IntEnable(ui8IntNumber);
+}
+
+//*****************************************************************************
+//
+//! Unregisters an interrupt handler for the CAN controller.
+//!
+//! \param ui32Base is the base address of the controller.
+//!
+//! This function unregisters the previously registered interrupt handler and
+//! disables the interrupt in the interrupt controller.
+//!
+//! \sa IntRegister() for important information about registering interrupt
+//! handlers.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANIntUnregister(uint32_t ui32Base)
+{
+ uint_fast8_t ui8IntNumber;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // Get the actual interrupt number for this CAN controller.
+ //
+ ui8IntNumber = _CANIntNumberGet(ui32Base);
+ ASSERT(ui8IntNumber != 0);
+
+ //
+ // Disable the CAN interrupt.
+ //
+ IntDisable(ui8IntNumber);
+
+ //
+ // Register the interrupt handler.
+ //
+ IntUnregister(ui8IntNumber);
+}
+
+//*****************************************************************************
+//
+//! Enables individual CAN controller interrupt sources.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param ui32IntFlags is the bit mask of the interrupt sources to be enabled.
+//!
+//! This function enables specific interrupt sources of the CAN controller.
+//! Only enabled sources cause a processor interrupt.
+//!
+//! The \e ui32IntFlags parameter is the logical OR of any of the following:
+//!
+//! - \b CAN_INT_ERROR - a controller error condition has occurred
+//! - \b CAN_INT_STATUS - a message transfer has completed, or a bus error has
+//! been detected
+//! - \b CAN_INT_MASTER - allow CAN controller to generate interrupts
+//!
+//! In order to generate any interrupts, \b CAN_INT_MASTER must be enabled.
+//! Further, for any particular transaction from a message object to generate
+//! an interrupt, that message object must have interrupts enabled (see
+//! CANMessageSet()). \b CAN_INT_ERROR generates an interrupt if the
+//! controller enters the ``bus off'' condition, or if the error counters reach
+//! a limit. \b CAN_INT_STATUS generates an interrupt under quite a few
+//! status conditions and may provide more interrupts than the application
+//! needs to handle. When an interrupt occurs, use CANIntStatus() to determine
+//! the cause.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANIntEnable(uint32_t ui32Base, uint32_t ui32IntFlags)
+{
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT((ui32IntFlags & ~(CAN_CTL_EIE | CAN_CTL_SIE | CAN_CTL_IE)) == 0);
+
+ //
+ // Enable the specified interrupts.
+ //
+ HWREG(ui32Base + CAN_O_CTL) |= ui32IntFlags;
+}
+
+//*****************************************************************************
+//
+//! Disables individual CAN controller interrupt sources.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param ui32IntFlags is the bit mask of the interrupt sources to be
+//! disabled.
+//!
+//! Disables the specified CAN controller interrupt sources. Only enabled
+//! interrupt sources can cause a processor interrupt.
+//!
+//! The \e ui32IntFlags parameter has the same definition as in the
+//! CANIntEnable() function.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANIntDisable(uint32_t ui32Base, uint32_t ui32IntFlags)
+{
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT((ui32IntFlags & ~(CAN_CTL_EIE | CAN_CTL_SIE | CAN_CTL_IE)) == 0);
+
+ //
+ // Disable the specified interrupts.
+ //
+ HWREG(ui32Base + CAN_O_CTL) &= ~ui32IntFlags;
+}
+
+//*****************************************************************************
+//
+//! Returns the current CAN controller interrupt status.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param eIntStsReg indicates which interrupt status register to read
+//!
+//! This function returns the value of one of two interrupt status registers.
+//! The interrupt status register read is determined by the \e eIntStsReg
+//! parameter, which can have one of the following values:
+//!
+//! - \b CAN_INT_STS_CAUSE - indicates the cause of the interrupt
+//! - \b CAN_INT_STS_OBJECT - indicates pending interrupts of all message
+//! objects
+//!
+//! \b CAN_INT_STS_CAUSE returns the value of the controller interrupt register
+//! and indicates the cause of the interrupt. The value returned is
+//! \b CAN_INT_INTID_STATUS if the cause is a status interrupt. In this case,
+//! the status register is read with the CANStatusGet() function.
+//! Calling this function to read the status also clears the status
+//! interrupt. If the value of the interrupt register is in the range 1-32,
+//! then this indicates the number of the highest priority message object that
+//! has an interrupt pending. The message object interrupt can be cleared by
+//! using the CANIntClear() function, or by reading the message using
+//! CANMessageGet() in the case of a received message. The interrupt handler
+//! can read the interrupt status again to make sure all pending interrupts are
+//! cleared before returning from the interrupt.
+//!
+//! \b CAN_INT_STS_OBJECT returns a bit mask indicating which message objects
+//! have pending interrupts. This value can be used to discover all of the
+//! pending interrupts at once, as opposed to repeatedly reading the interrupt
+//! register by using \b CAN_INT_STS_CAUSE.
+//!
+//! \return Returns the value of one of the interrupt status registers.
+//
+//*****************************************************************************
+uint32_t
+CANIntStatus(uint32_t ui32Base, tCANIntStsReg eIntStsReg)
+{
+ uint32_t ui32Status;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // See which status the caller is looking for.
+ //
+ switch(eIntStsReg)
+ {
+ //
+ // The caller wants the global interrupt status for the CAN controller
+ // specified by ui32Base.
+ //
+ case CAN_INT_STS_CAUSE:
+ {
+ ui32Status = HWREG(ui32Base + CAN_O_INT);
+ break;
+ }
+
+ //
+ // The caller wants the current message status interrupt for all
+ // messages.
+ //
+ case CAN_INT_STS_OBJECT:
+ {
+ //
+ // Read and combine both 16 bit values into one 32bit status.
+ //
+ ui32Status = (HWREG(ui32Base + CAN_O_MSG1INT) &
+ CAN_MSG1INT_INTPND_M);
+ ui32Status |= (HWREG(ui32Base + CAN_O_MSG2INT) << 16);
+ break;
+ }
+
+ //
+ // Request was for unknown status so just return 0.
+ //
+ default:
+ {
+ ui32Status = 0;
+ break;
+ }
+ }
+
+ //
+ // Return the interrupt status value
+ //
+ return(ui32Status);
+}
+
+//*****************************************************************************
+//
+//! Clears a CAN interrupt source.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param ui32IntClr is a value indicating which interrupt source to clear.
+//!
+//! This function can be used to clear a specific interrupt source. The
+//! \e ui32IntClr parameter must be one of the following values:
+//!
+//! - \b CAN_INT_INTID_STATUS - Clears a status interrupt.
+//! - 1-32 - Clears the specified message object interrupt
+//!
+//! It is not necessary to use this function to clear an interrupt. This
+//! function is only used if the application wants to clear an interrupt
+//! source without taking the normal interrupt action.
+//!
+//! Normally, the status interrupt is cleared by reading the controller status
+//! using CANStatusGet(). A specific message object interrupt is normally
+//! cleared by reading the message object using CANMessageGet().
+//!
+//! \note Because there is a write buffer in the Cortex-M processor, it may
+//! take several clock cycles before the interrupt source is actually cleared.
+//! Therefore, it is recommended that the interrupt source be cleared early in
+//! the interrupt handler (as opposed to the very last action) to avoid
+//! returning from the interrupt handler before the interrupt source is
+//! actually cleared. Failure to do so may result in the interrupt handler
+//! being immediately reentered (because the interrupt controller still sees
+//! the interrupt source asserted).
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANIntClear(uint32_t ui32Base, uint32_t ui32IntClr)
+{
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT((ui32IntClr == CAN_INT_INTID_STATUS) ||
+ ((ui32IntClr >= 1) && (ui32IntClr <= 32)));
+
+ if(ui32IntClr == CAN_INT_INTID_STATUS)
+ {
+ //
+ // Simply read and discard the status to clear the interrupt.
+ //
+ HWREG(ui32Base + CAN_O_STS);
+ }
+ else
+ {
+ //
+ // Wait to be sure that this interface is not busy.
+ //
+ while(HWREG(ui32Base + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // Only change the interrupt pending state by setting only the
+ // CAN_IF1CMSK_CLRINTPND bit.
+ //
+ HWREG(ui32Base + CAN_O_IF1CMSK) = CAN_IF1CMSK_CLRINTPND;
+
+ //
+ // Send the clear pending interrupt command to the CAN controller.
+ //
+ HWREG(ui32Base + CAN_O_IF1CRQ) = ui32IntClr & CAN_IF1CRQ_MNUM_M;
+
+ //
+ // Wait to be sure that this interface is not busy.
+ //
+ while(HWREG(ui32Base + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+ }
+}
+
+//*****************************************************************************
+//
+//! Sets the CAN controller automatic retransmission behavior.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param bAutoRetry enables automatic retransmission.
+//!
+//! This function enables or disables automatic retransmission of messages with
+//! detected errors. If \e bAutoRetry is \b true, then automatic
+//! retransmission is enabled, otherwise it is disabled.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANRetrySet(uint32_t ui32Base, bool bAutoRetry)
+{
+ uint32_t ui32CtlReg;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ ui32CtlReg = HWREG(ui32Base + CAN_O_CTL);
+
+ //
+ // Conditionally set the DAR bit to enable/disable auto-retry.
+ //
+ if(bAutoRetry)
+ {
+ //
+ // Clearing the DAR bit tells the controller to not disable the
+ // auto-retry of messages which were not transmitted or received
+ // correctly.
+ //
+ ui32CtlReg &= ~CAN_CTL_DAR;
+ }
+ else
+ {
+ //
+ // Setting the DAR bit tells the controller to disable the auto-retry
+ // of messages which were not transmitted or received correctly.
+ //
+ ui32CtlReg |= CAN_CTL_DAR;
+ }
+
+ HWREG(ui32Base + CAN_O_CTL) = ui32CtlReg;
+}
+
+//*****************************************************************************
+//
+//! Returns the current setting for automatic retransmission.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//!
+//! This function reads the current setting for automatic retransmission in the
+//! CAN controller and returns it to the caller.
+//!
+//! \return Returns \b true if automatic retransmission is enabled, \b false
+//! otherwise.
+//
+//*****************************************************************************
+bool
+CANRetryGet(uint32_t ui32Base)
+{
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // Read the disable automatic retry setting from the CAN controller.
+ //
+ if(HWREG(ui32Base + CAN_O_CTL) & CAN_CTL_DAR)
+ {
+ //
+ // Automatic data retransmission is not enabled.
+ //
+ return(false);
+ }
+
+ //
+ // Automatic data retransmission is enabled.
+ //
+ return(true);
+}
+
+//*****************************************************************************
+//
+//! Reads one of the controller status registers.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param eStatusReg is the status register to read.
+//!
+//! This function reads a status register of the CAN controller and returns it
+//! to the caller.
+//! The different status registers are:
+//!
+//! - \b CAN_STS_CONTROL - the main controller status
+//! - \b CAN_STS_TXREQUEST - bit mask of objects pending transmission
+//! - \b CAN_STS_NEWDAT - bit mask of objects with new data
+//! - \b CAN_STS_MSGVAL - bit mask of objects with valid configuration
+//!
+//! When reading the main controller status register, a pending status
+//! interrupt is cleared. This parameter is used in the interrupt
+//! handler for the CAN controller if the cause is a status interrupt. The
+//! controller status register fields are as follows:
+//!
+//! - \b CAN_STATUS_BUS_OFF - controller is in bus-off condition
+//! - \b CAN_STATUS_EWARN - an error counter has reached a limit of at least 96
+//! - \b CAN_STATUS_EPASS - CAN controller is in the error passive state
+//! - \b CAN_STATUS_RXOK - a message was received successfully (independent of
+//! any message filtering).
+//! - \b CAN_STATUS_TXOK - a message was successfully transmitted
+//! - \b CAN_STATUS_LEC_MSK - mask of last error code bits (3 bits)
+//! - \b CAN_STATUS_LEC_NONE - no error
+//! - \b CAN_STATUS_LEC_STUFF - stuffing error detected
+//! - \b CAN_STATUS_LEC_FORM - a format error occurred in the fixed format part
+//! of a message
+//! - \b CAN_STATUS_LEC_ACK - a transmitted message was not acknowledged
+//! - \b CAN_STATUS_LEC_BIT1 - dominant level detected when trying to send in
+//! recessive mode
+//! - \b CAN_STATUS_LEC_BIT0 - recessive level detected when trying to send in
+//! dominant mode
+//! - \b CAN_STATUS_LEC_CRC - CRC error in received message
+//!
+//! The remaining status registers consist of 32-bit-wide bit maps to the
+//! message objects. They can be used to quickly obtain information about the
+//! status of all the message objects without needing to query each one. They
+//! contain the following information:
+//!
+//! - \b CAN_STS_TXREQUEST - if a message object's TXRQST bit is set, a
+//! transmission is pending on that object. The application can use this
+//! information to determine which objects are still waiting to send a
+//! message.
+//! - \b CAN_STS_NEWDAT - if a message object's NEWDAT bit is set, a new
+//! message has been received in that object, and has not yet been picked up
+//! by the host application
+//! - \b CAN_STS_MSGVAL - if a message object's MSGVAL bit is set, the object
+//! has a valid configuration programmed. The host application can use this
+//! information to determine which message objects are empty/unused.
+//!
+//! \return Returns the value of the status register.
+//
+//*****************************************************************************
+uint32_t
+CANStatusGet(uint32_t ui32Base, tCANStsReg eStatusReg)
+{
+ uint32_t ui32Status;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ switch(eStatusReg)
+ {
+ //
+ // Just return the global CAN status register since that is what was
+ // requested.
+ //
+ case CAN_STS_CONTROL:
+ {
+ ui32Status = HWREG(ui32Base + CAN_O_STS);
+ HWREG(ui32Base + CAN_O_STS) = ~(CAN_STS_RXOK | CAN_STS_TXOK |
+ CAN_STS_LEC_M);
+ break;
+ }
+
+ //
+ // Combine the Transmit status bits into one 32bit value.
+ //
+ case CAN_STS_TXREQUEST:
+ {
+ ui32Status = HWREG(ui32Base + CAN_O_TXRQ1);
+ ui32Status |= HWREG(ui32Base + CAN_O_TXRQ2) << 16;
+ break;
+ }
+
+ //
+ // Combine the New Data status bits into one 32bit value.
+ //
+ case CAN_STS_NEWDAT:
+ {
+ ui32Status = HWREG(ui32Base + CAN_O_NWDA1);
+ ui32Status |= HWREG(ui32Base + CAN_O_NWDA2) << 16;
+ break;
+ }
+
+ //
+ // Combine the Message valid status bits into one 32bit value.
+ //
+ case CAN_STS_MSGVAL:
+ {
+ ui32Status = HWREG(ui32Base + CAN_O_MSG1VAL);
+ ui32Status |= HWREG(ui32Base + CAN_O_MSG2VAL) << 16;
+ break;
+ }
+
+ //
+ // Unknown CAN status requested so return 0.
+ //
+ default:
+ {
+ ui32Status = 0;
+ break;
+ }
+ }
+ return(ui32Status);
+}
+
+//*****************************************************************************
+//
+//! Reads the CAN controller error counter register.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param pui32RxCount is a pointer to storage for the receive error counter.
+//! \param pui32TxCount is a pointer to storage for the transmit error counter.
+//!
+//! This function reads the error counter register and returns the transmit and
+//! receive error counts to the caller along with a flag indicating if the
+//! controller receive counter has reached the error passive limit. The values
+//! of the receive and transmit error counters are returned through the
+//! pointers provided as parameters.
+//!
+//! After this call, \e *pui32RxCount holds the current receive error count
+//! and \e *pui32TxCount holds the current transmit error count.
+//!
+//! \return Returns \b true if the receive error count has reached the error
+//! passive limit, and \b false if the error count is below the error passive
+//! limit.
+//
+//*****************************************************************************
+bool
+CANErrCntrGet(uint32_t ui32Base, uint32_t *pui32RxCount,
+ uint32_t *pui32TxCount)
+{
+ uint32_t ui32CANError;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+
+ //
+ // Read the current count of transmit/receive errors.
+ //
+ ui32CANError = HWREG(ui32Base + CAN_O_ERR);
+
+ //
+ // Extract the error numbers from the register value.
+ //
+ *pui32RxCount = (ui32CANError & CAN_ERR_REC_M) >> CAN_ERR_REC_S;
+ *pui32TxCount = (ui32CANError & CAN_ERR_TEC_M) >> CAN_ERR_TEC_S;
+
+ if(ui32CANError & CAN_ERR_RP)
+ {
+ return(true);
+ }
+ return(false);
+}
+
+//*****************************************************************************
+//
+//! Configures a message object in the CAN controller.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param ui32ObjID is the object number to configure (1-32).
+//! \param psMsgObject is a pointer to a structure containing message object
+//! settings.
+//! \param eMsgType indicates the type of message for this object.
+//!
+//! This function is used to configure any one of the 32 message objects in the
+//! CAN controller. A message object can be configured to be any type of CAN
+//! message object as well as to use automatic transmission and reception.
+//! This call also allows the message object to be configured to generate
+//! interrupts on completion of message receipt or transmission. The
+//! message object can also be configured with a filter/mask so that actions
+//! are only taken when a message that meets certain parameters is seen on the
+//! CAN bus.
+//!
+//! The \e eMsgType parameter must be one of the following values:
+//!
+//! - \b MSG_OBJ_TYPE_TX - CAN transmit message object.
+//! - \b MSG_OBJ_TYPE_TX_REMOTE - CAN transmit remote request message object.
+//! - \b MSG_OBJ_TYPE_RX - CAN receive message object.
+//! - \b MSG_OBJ_TYPE_RX_REMOTE - CAN receive remote request message object.
+//! - \b MSG_OBJ_TYPE_RXTX_REMOTE - CAN remote frame receive remote, then
+//! transmit message object.
+//!
+//! The message object pointed to by \e psMsgObject must be populated by the
+//! caller, as follows:
+//!
+//! - \e ui32MsgID - contains the message ID, either 11 or 29 bits.
+//! - \e ui32MsgIDMask - mask of bits from \e ui32MsgID that must match if
+//! identifier filtering is enabled.
+//! - \e ui32Flags
+//! - Set \b MSG_OBJ_TX_INT_ENABLE flag to enable interrupt on transmission.
+//! - Set \b MSG_OBJ_RX_INT_ENABLE flag to enable interrupt on receipt.
+//! - Set \b MSG_OBJ_USE_ID_FILTER flag to enable filtering based on the
+//! identifier mask specified by \e ui32MsgIDMask.
+//! - \e ui32MsgLen - the number of bytes in the message data. This parameter
+//! must be non-zero even for a remote frame; it must match the expected
+//! bytes of data in the responding data frame.
+//! - \e pui8MsgData - points to a buffer containing up to 8 bytes of data for
+//! a data frame.
+//!
+//! \b Example: To send a data frame or remote frame (in response to a remote
+//! request), take the following steps:
+//!
+//! -# Set \e eMsgType to \b MSG_OBJ_TYPE_TX.
+//! -# Set \e psMsgObject->ui32MsgID to the message ID.
+//! -# Set \e psMsgObject->ui32Flags. Make sure to set
+//! \b MSG_OBJ_TX_INT_ENABLE to allow an interrupt to be generated when the
+//! message is sent.
+//! -# Set \e psMsgObject->ui32MsgLen to the number of bytes in the data frame.
+//! -# Set \e psMsgObject->pui8MsgData to point to an array containing the
+//! bytes to send in the message.
+//! -# Call this function with \e ui32ObjID set to one of the 32 object
+//! buffers.
+//!
+//! \b Example: To receive a specific data frame, take the following steps:
+//!
+//! -# Set \e eMsgObjType to \b MSG_OBJ_TYPE_RX.
+//! -# Set \e psMsgObject->ui32MsgID to the full message ID, or a partial mask
+//! to use partial ID matching.
+//! -# Set \e psMsgObject->ui32MsgIDMask bits that are used for masking
+//! during comparison.
+//! -# Set \e psMsgObject->ui32Flags as follows:
+//! - Set \b MSG_OBJ_RX_INT_ENABLE flag to be interrupted when the data
+//! frame is received.
+//! - Set \b MSG_OBJ_USE_ID_FILTER flag to enable identifier-based
+//! filtering.
+//! -# Set \e psMsgObject->ui32MsgLen to the number of bytes in the expected
+//! data frame.
+//! -# The buffer pointed to by \e psMsgObject->pui8MsgData is not used by this
+//! call as no data is present at the time of the call.
+//! -# Call this function with \e ui32ObjID set to one of the 32 object
+//! buffers.
+//!
+//! If you specify a message object buffer that already contains a message
+//! definition, it is overwritten.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANMessageSet(uint32_t ui32Base, uint32_t ui32ObjID,
+ tCANMsgObject *psMsgObject, tMsgObjType eMsgType)
+{
+ uint16_t ui16CmdMaskReg;
+ uint16_t ui16MaskReg0, ui16MaskReg1;
+ uint16_t ui16ArbReg0, ui16ArbReg1;
+ uint16_t ui16MsgCtrl;
+ bool bTransferData;
+ bool bUseExtendedID;
+
+ bTransferData = 0;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT((ui32ObjID <= 32) && (ui32ObjID != 0));
+ ASSERT((eMsgType == MSG_OBJ_TYPE_TX) ||
+ (eMsgType == MSG_OBJ_TYPE_TX_REMOTE) ||
+ (eMsgType == MSG_OBJ_TYPE_RX) ||
+ (eMsgType == MSG_OBJ_TYPE_RX_REMOTE) ||
+ (eMsgType == MSG_OBJ_TYPE_TX_REMOTE) ||
+ (eMsgType == MSG_OBJ_TYPE_RXTX_REMOTE));
+
+ //
+ // Wait for busy bit to clear
+ //
+ while(HWREG(ui32Base + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // See if we need to use an extended identifier or not.
+ //
+ if((psMsgObject->ui32MsgID > CAN_MAX_11BIT_MSG_ID) ||
+ (psMsgObject->ui32Flags & MSG_OBJ_EXTENDED_ID))
+ {
+ bUseExtendedID = 1;
+ }
+ else
+ {
+ bUseExtendedID = 0;
+ }
+
+ //
+ // This is always a write to the Message object as this call is setting a
+ // message object. This call always sets all size bits so it sets
+ // both data bits. The call uses the CONTROL register to set control
+ // bits so this bit needs to be set as well.
+ //
+ ui16CmdMaskReg = (CAN_IF1CMSK_WRNRD | CAN_IF1CMSK_DATAA |
+ CAN_IF1CMSK_DATAB | CAN_IF1CMSK_CONTROL);
+
+ //
+ // Initialize the values to a known state before filling them in based on
+ // the type of message object that is being configured.
+ //
+ ui16ArbReg0 = 0;
+ ui16ArbReg1 = 0;
+ ui16MsgCtrl = 0;
+ ui16MaskReg0 = 0;
+ ui16MaskReg1 = 0;
+
+ switch(eMsgType)
+ {
+ //
+ // Transmit message object.
+ //
+ case MSG_OBJ_TYPE_TX:
+ {
+ //
+ // Set the TXRQST bit and the reset the rest of the register.
+ //
+ ui16MsgCtrl |= CAN_IF1MCTL_TXRQST;
+ ui16ArbReg1 = CAN_IF1ARB2_DIR;
+ bTransferData = 1;
+ break;
+ }
+
+ //
+ // Transmit remote request message object
+ //
+ case MSG_OBJ_TYPE_TX_REMOTE:
+ {
+ //
+ // Set the TXRQST bit and the reset the rest of the register.
+ //
+ ui16MsgCtrl |= CAN_IF1MCTL_TXRQST;
+ ui16ArbReg1 = 0;
+ break;
+ }
+
+ //
+ // Receive message object.
+ //
+ case MSG_OBJ_TYPE_RX:
+ {
+ //
+ // This clears the DIR bit along with everything else. The TXRQST
+ // bit was cleared by defaulting ui16MsgCtrl to 0.
+ //
+ ui16ArbReg1 = 0;
+ break;
+ }
+
+ //
+ // Receive remote request message object.
+ //
+ case MSG_OBJ_TYPE_RX_REMOTE:
+ {
+ //
+ // The DIR bit is set to one for remote receivers. The TXRQST bit
+ // was cleared by defaulting ui16MsgCtrl to 0.
+ //
+ ui16ArbReg1 = CAN_IF1ARB2_DIR;
+
+ //
+ // Set this object so that it only indicates that a remote frame
+ // was received and allow for software to handle it by sending back
+ // a data frame.
+ //
+ ui16MsgCtrl = CAN_IF1MCTL_UMASK;
+
+ //
+ // Use the full Identifier by default.
+ //
+ ui16MaskReg0 = 0xffff;
+ ui16MaskReg1 = 0x1fff;
+
+ //
+ // Make sure to send the mask to the message object.
+ //
+ ui16CmdMaskReg |= CAN_IF1CMSK_MASK;
+ break;
+ }
+
+ //
+ // Remote frame receive remote, with auto-transmit message object.
+ //
+ case MSG_OBJ_TYPE_RXTX_REMOTE:
+ {
+ //
+ // Oddly the DIR bit is set to one for remote receivers.
+ //
+ ui16ArbReg1 = CAN_IF1ARB2_DIR;
+
+ //
+ // Set this object to auto answer if a matching identifier is seen.
+ //
+ ui16MsgCtrl = CAN_IF1MCTL_RMTEN | CAN_IF1MCTL_UMASK;
+
+ //
+ // The data to be returned needs to be filled in.
+ //
+ bTransferData = 1;
+ break;
+ }
+
+ //
+ // This case never happens due to the ASSERT statement at the
+ // beginning of this function.
+ //
+ default:
+ {
+ return;
+ }
+ }
+
+ //
+ // Configure the Mask Registers.
+ //
+ if(psMsgObject->ui32Flags & MSG_OBJ_USE_ID_FILTER)
+ {
+ if(bUseExtendedID)
+ {
+ //
+ // Set the 29 bits of Identifier mask that were requested.
+ //
+ ui16MaskReg0 = psMsgObject->ui32MsgIDMask & CAN_IF1MSK1_IDMSK_M;
+ ui16MaskReg1 = ((psMsgObject->ui32MsgIDMask >> 16) &
+ CAN_IF1MSK2_IDMSK_M);
+ }
+ else
+ {
+ //
+ // Lower 16 bit are unused so set them to zero.
+ //
+ ui16MaskReg0 = 0;
+
+ //
+ // Put the 11 bit Mask Identifier into the upper bits of the field
+ // in the register.
+ //
+ ui16MaskReg1 = ((psMsgObject->ui32MsgIDMask << 2) &
+ CAN_IF1MSK2_IDMSK_M);
+ }
+ }
+
+ //
+ // If the caller wants to filter on the extended ID bit then set it.
+ //
+ if((psMsgObject->ui32Flags & MSG_OBJ_USE_EXT_FILTER) ==
+ MSG_OBJ_USE_EXT_FILTER)
+ {
+ ui16MaskReg1 |= CAN_IF1MSK2_MXTD;
+ }
+
+ //
+ // The caller wants to filter on the message direction field.
+ //
+ if((psMsgObject->ui32Flags & MSG_OBJ_USE_DIR_FILTER) ==
+ MSG_OBJ_USE_DIR_FILTER)
+ {
+ ui16MaskReg1 |= CAN_IF1MSK2_MDIR;
+ }
+
+ if(psMsgObject->ui32Flags &
+ (MSG_OBJ_USE_ID_FILTER | MSG_OBJ_USE_DIR_FILTER |
+ MSG_OBJ_USE_EXT_FILTER))
+ {
+ //
+ // Set the UMASK bit to enable using the mask register.
+ //
+ ui16MsgCtrl |= CAN_IF1MCTL_UMASK;
+
+ //
+ // Set the MASK bit so that this gets transferred to the Message
+ // Object.
+ //
+ ui16CmdMaskReg |= CAN_IF1CMSK_MASK;
+ }
+
+ //
+ // Set the Arb bit so that this gets transferred to the Message object.
+ //
+ ui16CmdMaskReg |= CAN_IF1CMSK_ARB;
+
+ //
+ // Configure the Arbitration registers.
+ //
+ if(bUseExtendedID)
+ {
+ //
+ // Set the 29 bit version of the Identifier for this message object.
+ //
+ ui16ArbReg0 |= psMsgObject->ui32MsgID & CAN_IF1ARB1_ID_M;
+ ui16ArbReg1 |= (psMsgObject->ui32MsgID >> 16) & CAN_IF1ARB2_ID_M;
+
+ //
+ // Mark the message as valid and set the extended ID bit.
+ //
+ ui16ArbReg1 |= CAN_IF1ARB2_MSGVAL | CAN_IF1ARB2_XTD;
+ }
+ else
+ {
+ //
+ // Set the 11 bit version of the Identifier for this message object.
+ // The lower 18 bits are set to zero.
+ //
+ ui16ArbReg1 |= (psMsgObject->ui32MsgID << 2) & CAN_IF1ARB2_ID_M;
+
+ //
+ // Mark the message as valid.
+ //
+ ui16ArbReg1 |= CAN_IF1ARB2_MSGVAL;
+ }
+
+ //
+ // Set the data length since this is set for all transfers. This is also a
+ // single transfer and not a FIFO transfer so set EOB bit.
+ //
+ ui16MsgCtrl |= (psMsgObject->ui32MsgLen & CAN_IF1MCTL_DLC_M);
+
+ //
+ // Mark this as the last entry if this is not the last entry in a FIFO.
+ //
+ if((psMsgObject->ui32Flags & MSG_OBJ_FIFO) == 0)
+ {
+ ui16MsgCtrl |= CAN_IF1MCTL_EOB;
+ }
+
+ //
+ // Enable transmit interrupts if they should be enabled.
+ //
+ if(psMsgObject->ui32Flags & MSG_OBJ_TX_INT_ENABLE)
+ {
+ ui16MsgCtrl |= CAN_IF1MCTL_TXIE;
+ }
+
+ //
+ // Enable receive interrupts if they should be enabled.
+ //
+ if(psMsgObject->ui32Flags & MSG_OBJ_RX_INT_ENABLE)
+ {
+ ui16MsgCtrl |= CAN_IF1MCTL_RXIE;
+ }
+
+ //
+ // Write the data out to the CAN Data registers if needed.
+ //
+ if(bTransferData)
+ {
+ _CANDataRegWrite(psMsgObject->pui8MsgData,
+ (uint32_t *)(ui32Base + CAN_O_IF1DA1),
+ psMsgObject->ui32MsgLen);
+ }
+
+ //
+ // Write out the registers to program the message object.
+ //
+ HWREG(ui32Base + CAN_O_IF1CMSK) = ui16CmdMaskReg;
+ HWREG(ui32Base + CAN_O_IF1MSK1) = ui16MaskReg0;
+ HWREG(ui32Base + CAN_O_IF1MSK2) = ui16MaskReg1;
+ HWREG(ui32Base + CAN_O_IF1ARB1) = ui16ArbReg0;
+ HWREG(ui32Base + CAN_O_IF1ARB2) = ui16ArbReg1;
+ HWREG(ui32Base + CAN_O_IF1MCTL) = ui16MsgCtrl;
+
+ //
+ // Transfer the message object to the message object specified by
+ // ui32ObjID.
+ //
+ HWREG(ui32Base + CAN_O_IF1CRQ) = ui32ObjID & CAN_IF1CRQ_MNUM_M;
+}
+
+//*****************************************************************************
+//
+//! Reads a CAN message from one of the message object buffers.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param ui32ObjID is the object number to read (1-32).
+//! \param psMsgObject points to a structure containing message object fields.
+//! \param bClrPendingInt indicates whether an associated interrupt should be
+//! cleared.
+//!
+//! This function is used to read the contents of one of the 32 message objects
+//! in the CAN controller and return it to the caller. The data returned is
+//! stored in the fields of the caller-supplied structure pointed to by
+//! \e psMsgObject. The data consists of all of the parts of a CAN message,
+//! plus some control and status information.
+//!
+//! Normally, this function is used to read a message object that has received
+//! and stored a CAN message with a certain identifier. However, this function
+//! could also be used to read the contents of a message object in order to
+//! load the fields of the structure in case only part of the structure must
+//! be changed from a previous setting.
+//!
+//! When using CANMessageGet(), all of the same fields of the structure are
+//! populated in the same way as when the CANMessageSet() function is used,
+//! with the following exceptions:
+//!
+//! \e psMsgObject->ui32Flags:
+//!
+//! - \b MSG_OBJ_NEW_DATA indicates if this data is new since the last time it
+//! was read
+//! - \b MSG_OBJ_DATA_LOST indicates that at least one message was received on
+//! this message object and not read by the host before being overwritten.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANMessageGet(uint32_t ui32Base, uint32_t ui32ObjID,
+ tCANMsgObject *psMsgObject, bool bClrPendingInt)
+{
+ uint16_t ui16CmdMaskReg;
+ uint16_t ui16MaskReg0, ui16MaskReg1;
+ uint16_t ui16ArbReg0, ui16ArbReg1;
+ uint16_t ui16MsgCtrl;
+
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT((ui32ObjID <= 32) && (ui32ObjID != 0));
+
+ //
+ // This is always a read to the Message object as this call is setting a
+ // message object.
+ //
+ ui16CmdMaskReg = (CAN_IF1CMSK_DATAA | CAN_IF1CMSK_DATAB |
+ CAN_IF1CMSK_CONTROL | CAN_IF1CMSK_MASK |
+ CAN_IF1CMSK_ARB);
+
+ //
+ // Clear a pending interrupt and new data in a message object.
+ //
+ if(bClrPendingInt)
+ {
+ ui16CmdMaskReg |= CAN_IF1CMSK_CLRINTPND;
+ }
+
+ //
+ // Set up the request for data from the message object.
+ //
+ HWREG(ui32Base + CAN_O_IF2CMSK) = ui16CmdMaskReg;
+
+ //
+ // Transfer the message object to the message object specified by
+ // ui32ObjID.
+ //
+ HWREG(ui32Base + CAN_O_IF2CRQ) = ui32ObjID & CAN_IF1CRQ_MNUM_M;
+
+ //
+ // Wait for busy bit to clear
+ //
+ while(HWREG(ui32Base + CAN_O_IF2CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // Read out the IF Registers.
+ //
+ ui16MaskReg0 = HWREG(ui32Base + CAN_O_IF2MSK1);
+ ui16MaskReg1 = HWREG(ui32Base + CAN_O_IF2MSK2);
+ ui16ArbReg0 = HWREG(ui32Base + CAN_O_IF2ARB1);
+ ui16ArbReg1 = HWREG(ui32Base + CAN_O_IF2ARB2);
+ ui16MsgCtrl = HWREG(ui32Base + CAN_O_IF2MCTL);
+
+ psMsgObject->ui32Flags = MSG_OBJ_NO_FLAGS;
+
+ //
+ // Determine if this is a remote frame by checking the TXRQST and DIR bits.
+ //
+ if((!(ui16MsgCtrl & CAN_IF1MCTL_TXRQST) &&
+ (ui16ArbReg1 & CAN_IF1ARB2_DIR)) ||
+ ((ui16MsgCtrl & CAN_IF1MCTL_TXRQST) &&
+ (!(ui16ArbReg1 & CAN_IF1ARB2_DIR))))
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_REMOTE_FRAME;
+ }
+
+ //
+ // Get the identifier out of the register, the format depends on size of
+ // the mask.
+ //
+ if(ui16ArbReg1 & CAN_IF1ARB2_XTD)
+ {
+ //
+ // Set the 29 bit version of the Identifier for this message object.
+ //
+ psMsgObject->ui32MsgID = (((ui16ArbReg1 & CAN_IF1ARB2_ID_M) << 16) |
+ ui16ArbReg0);
+
+ psMsgObject->ui32Flags |= MSG_OBJ_EXTENDED_ID;
+ }
+ else
+ {
+ //
+ // The Identifier is an 11 bit value.
+ //
+ psMsgObject->ui32MsgID = (ui16ArbReg1 & CAN_IF1ARB2_ID_M) >> 2;
+ }
+
+ //
+ // Indicate that we lost some data.
+ //
+ if(ui16MsgCtrl & CAN_IF1MCTL_MSGLST)
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_DATA_LOST;
+ }
+
+ //
+ // Set the flag to indicate if ID masking was used.
+ //
+ if(ui16MsgCtrl & CAN_IF1MCTL_UMASK)
+ {
+ if(ui16ArbReg1 & CAN_IF1ARB2_XTD)
+ {
+ //
+ // The Identifier Mask is assumed to also be a 29 bit value.
+ //
+ psMsgObject->ui32MsgIDMask =
+ ((ui16MaskReg1 & CAN_IF1MSK2_IDMSK_M) << 16) | ui16MaskReg0;
+
+ //
+ // If this is a fully specified Mask and a remote frame then don't
+ // set the MSG_OBJ_USE_ID_FILTER because the ID was not really
+ // filtered.
+ //
+ if((psMsgObject->ui32MsgIDMask != 0x1fffffff) ||
+ ((psMsgObject->ui32Flags & MSG_OBJ_REMOTE_FRAME) == 0))
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_USE_ID_FILTER;
+ }
+ }
+ else
+ {
+ //
+ // The Identifier Mask is assumed to also be an 11 bit value.
+ //
+ psMsgObject->ui32MsgIDMask =
+ (ui16MaskReg1 & CAN_IF1MSK2_IDMSK_M) >> 2;
+
+ //
+ // If this is a fully specified Mask and a remote frame then don't
+ // set the MSG_OBJ_USE_ID_FILTER because the ID was not really
+ // filtered.
+ //
+ if((psMsgObject->ui32MsgIDMask != 0x7ff) ||
+ ((psMsgObject->ui32Flags & MSG_OBJ_REMOTE_FRAME) == 0))
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_USE_ID_FILTER;
+ }
+ }
+
+ //
+ // Indicate if the extended bit was used in filtering.
+ //
+ if(ui16MaskReg1 & CAN_IF1MSK2_MXTD)
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_USE_EXT_FILTER;
+ }
+
+ //
+ // Indicate if direction filtering was enabled.
+ //
+ if(ui16MaskReg1 & CAN_IF1MSK2_MDIR)
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_USE_DIR_FILTER;
+ }
+ }
+
+ //
+ // Set the interrupt flags.
+ //
+ if(ui16MsgCtrl & CAN_IF1MCTL_TXIE)
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_TX_INT_ENABLE;
+ }
+ if(ui16MsgCtrl & CAN_IF1MCTL_RXIE)
+ {
+ psMsgObject->ui32Flags |= MSG_OBJ_RX_INT_ENABLE;
+ }
+
+ //
+ // See if there is new data available.
+ //
+ if(ui16MsgCtrl & CAN_IF1MCTL_NEWDAT)
+ {
+ //
+ // Get the amount of data needed to be read.
+ //
+ psMsgObject->ui32MsgLen = (ui16MsgCtrl & CAN_IF1MCTL_DLC_M);
+
+ //
+ // Don't read any data for a remote frame, there is nothing valid in
+ // that buffer anyway.
+ //
+ if((psMsgObject->ui32Flags & MSG_OBJ_REMOTE_FRAME) == 0)
+ {
+ //
+ // Read out the data from the CAN registers.
+ //
+ _CANDataRegRead(psMsgObject->pui8MsgData,
+ (uint32_t *)(ui32Base + CAN_O_IF2DA1),
+ psMsgObject->ui32MsgLen);
+ }
+
+ //
+ // Now clear out the new data flag.
+ //
+ HWREG(ui32Base + CAN_O_IF2CMSK) = CAN_IF1CMSK_NEWDAT;
+
+ //
+ // Transfer the message object to the message object specified by
+ // ui32ObjID.
+ //
+ HWREG(ui32Base + CAN_O_IF2CRQ) = ui32ObjID & CAN_IF1CRQ_MNUM_M;
+
+ //
+ // Wait for busy bit to clear
+ //
+ while(HWREG(ui32Base + CAN_O_IF2CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // Indicate that there is new data in this message.
+ //
+ psMsgObject->ui32Flags |= MSG_OBJ_NEW_DATA;
+ }
+ else
+ {
+ //
+ // Along with the MSG_OBJ_NEW_DATA not being set the amount of data
+ // needs to be set to zero if none was available.
+ //
+ psMsgObject->ui32MsgLen = 0;
+ }
+}
+
+//*****************************************************************************
+//
+//! Clears a message object so that it is no longer used.
+//!
+//! \param ui32Base is the base address of the CAN controller.
+//! \param ui32ObjID is the message object number to disable (1-32).
+//!
+//! This function frees the specified message object from use. Once a message
+//! object has been ``cleared,'' it no longer automatically sends or receives
+//! messages, nor does it generate interrupts.
+//!
+//! \return None.
+//
+//*****************************************************************************
+void
+CANMessageClear(uint32_t ui32Base, uint32_t ui32ObjID)
+{
+ //
+ // Check the arguments.
+ //
+ ASSERT(_CANBaseValid(ui32Base));
+ ASSERT((ui32ObjID >= 1) && (ui32ObjID <= 32));
+
+ //
+ // Wait for busy bit to clear
+ //
+ while(HWREG(ui32Base + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
+ {
+ }
+
+ //
+ // Clear the message value bit in the arbitration register. This indicates
+ // the message is not valid.
+ //
+ HWREG(ui32Base + CAN_O_IF1CMSK) = CAN_IF1CMSK_WRNRD | CAN_IF1CMSK_ARB;
+ HWREG(ui32Base + CAN_O_IF1ARB1) = 0;
+ HWREG(ui32Base + CAN_O_IF1ARB2) = 0;
+
+ //
+ // Initiate programming the message object
+ //
+ HWREG(ui32Base + CAN_O_IF1CRQ) = ui32ObjID & CAN_IF1CRQ_MNUM_M;
+}
+
+//*****************************************************************************
+//
+// Close the Doxygen group.
+//! @}
+//
+//*****************************************************************************
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