From e018ceebed74b8223482bc9d1ed0b31c938381da Mon Sep 17 00:00:00 2001 From: Yuval Adam Date: Mon, 29 Oct 2012 23:04:19 +0200 Subject: New example files --- boards/ek-lm4f120xl/bitband/bitband.c | 220 ++++++++++++++++++++++++++++++++++ 1 file changed, 220 insertions(+) create mode 100644 boards/ek-lm4f120xl/bitband/bitband.c (limited to 'boards/ek-lm4f120xl/bitband/bitband.c') diff --git a/boards/ek-lm4f120xl/bitband/bitband.c b/boards/ek-lm4f120xl/bitband/bitband.c new file mode 100644 index 0000000..52b1b15 --- /dev/null +++ b/boards/ek-lm4f120xl/bitband/bitband.c @@ -0,0 +1,220 @@ +//***************************************************************************** +// +// bitband.c - Bit-band manipulation example. +// +// Copyright (c) 2012 Texas Instruments Incorporated. All rights reserved. +// Software License Agreement +// +// Texas Instruments (TI) is supplying this software for use solely and +// exclusively on TI's microcontroller products. The software is owned by +// TI and/or its suppliers, and is protected under applicable copyright +// laws. You may not combine this software with "viral" open-source +// software in order to form a larger program. +// +// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS. +// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT +// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY +// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL +// DAMAGES, FOR ANY REASON WHATSOEVER. +// +// This is part of revision 9453 of the EK-LM4F120XL Firmware Package. +// +//***************************************************************************** + +#include "inc/hw_memmap.h" +#include "inc/hw_types.h" +#include "driverlib/debug.h" +#include "driverlib/gpio.h" +#include "driverlib/fpu.h" +#include "driverlib/pin_map.h" +#include "driverlib/sysctl.h" +#include "driverlib/systick.h" +#include "driverlib/rom.h" +#include "utils/uartstdio.h" + +//***************************************************************************** +// +//! \addtogroup example_list +//!

Bit-Banding (bitband)

+//! +//! This example application demonstrates the use of the bit-banding +//! capabilities of the Cortex-M4F microprocessor. All of SRAM and all of the +//! peripherals reside within bit-band regions, meaning that bit-banding +//! operations can be applied to any of them. In this example, a variable in +//! SRAM is set to a particular value one bit at a time using bit-banding +//! operations (it would be more efficient to do a single non-bit-banded write; +//! this simply demonstrates the operation of bit-banding). +// +//***************************************************************************** + + +//***************************************************************************** +// +// The value that is to be modified via bit-banding. +// +//***************************************************************************** +static volatile unsigned long g_ulValue; + +//***************************************************************************** +// +// The error routine that is called if the driver library encounters an error. +// +//***************************************************************************** +#ifdef DEBUG +void +__error__(char *pcFilename, unsigned long ulLine) +{ +} +#endif + +//***************************************************************************** +// +// Delay for the specified number of seconds. Depending upon the current +// SysTick value, the delay will be between N-1 and N seconds (i.e. N-1 full +// seconds are guaranteed, along with the remainder of the current second). +// +//***************************************************************************** +void +Delay(unsigned long ulSeconds) +{ + // + // Loop while there are more seconds to wait. + // + while(ulSeconds--) + { + // + // Wait until the SysTick value is less than 1000. + // + while(ROM_SysTickValueGet() > 1000) + { + } + + // + // Wait until the SysTick value is greater than 1000. + // + while(ROM_SysTickValueGet() < 1000) + { + } + } +} + + +//***************************************************************************** +// +// This example demonstrates the use of bit-banding to set individual bits +// within a word of SRAM. +// +//***************************************************************************** +int +main(void) +{ + unsigned long ulErrors, ulIdx; + + // + // Enable lazy stacking for interrupt handlers. This allows floating-point + // instructions to be used within interrupt handlers, but at the expense of + // extra stack usage. + // + ROM_FPULazyStackingEnable(); + + // + // Set the clocking to run directly from the crystal. + // + ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN | + SYSCTL_XTAL_16MHZ); + + // + // Initialize the UART interface. + // + ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA); + GPIOPinConfigure(GPIO_PA0_U0RX); + GPIOPinConfigure(GPIO_PA1_U0TX); + ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1); + UARTStdioInit(0); + UARTprintf("\033[2JBit banding...\n"); + + // + // Set up and enable the SysTick timer. It will be used as a reference + // for delay loops. The SysTick timer period will be set up for one + // second. + // + ROM_SysTickPeriodSet(ROM_SysCtlClockGet()); + ROM_SysTickEnable(); + + // + // Set the value and error count to zero. + // + g_ulValue = 0; + ulErrors = 0; + + // + // Print the initial value to the UART. + // + UARTprintf("\r%08x", g_ulValue); + + // + // Delay for 1 second. + // + Delay(1); + + // + // Set the value to 0xdecafbad using bit band accesses to each individual + // bit. + // + for(ulIdx = 0; ulIdx < 32; ulIdx++) + { + // + // Set this bit. + // + HWREGBITW(&g_ulValue, 31 - ulIdx) = (0xdecafbad >> (31 - ulIdx)) & 1; + + // + // Print the current value to the UART. + // + UARTprintf("\r%08x", g_ulValue); + + // + // Delay for 1 second. + // + Delay(1); + } + + // + // Make sure that the value is 0xdecafbad. + // + if(g_ulValue != 0xdecafbad) + { + ulErrors++; + } + + // + // Make sure that the individual bits read back correctly. + // + for(ulIdx = 0; ulIdx < 32; ulIdx++) + { + if(HWREGBITW(&g_ulValue, ulIdx) != ((0xdecafbad >> ulIdx) & 1)) + { + ulErrors++; + } + } + + // + // Print out the result. + // + if(ulErrors) + { + UARTprintf("\nErrors!\n"); + } + else + { + UARTprintf("\nSuccess!\n"); + } + + // + // Loop forever. + // + while(1) + { + } +} -- cgit v1.3.1