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//*****************************************************************************
//
// gpio_jtag.c - Example to demonstrate recovering the JTAG interface.
//
// 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_gpio.h"
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.h"
#include "utils/uartstdio.h"
#include "drivers/buttons.h"
//*****************************************************************************
//
//! \addtogroup example_list
//! <h1>GPIO JTAG Recovery (gpio_jtag)</h1>
//!
//! This example demonstrates changing the JTAG pins into GPIOs, along with a
//! mechanism to revert them to JTAG pins. When first run, the pins remain in
//! JTAG mode. Pressing the left button will toggle the pins between JTAG mode
//! and GPIO mode. Because there is no debouncing of the push button (either
//! in hardware or software), a button press will occasionally result in more
//! than one mode change.
//!
//! In this example, four pins (PC0, PC1, PC2, and PC3) are switched.
//!
//! UART0, connected to the ICDI virtual COM port and running at 115,200,
//! 8-N-1, is used to display messages from this application.
//
//*****************************************************************************
//*****************************************************************************
//
// The current mode of pins PC0, PC1, PC2, and PC3. When zero, the pins
// are in JTAG mode; when non-zero, the pins are in GPIO mode.
//
//*****************************************************************************
volatile unsigned long g_ulMode;
//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, unsigned long ulLine)
{
}
#endif
//*****************************************************************************
//
// The interrupt handler for the PB4 pin interrupt. When triggered, this will
// toggle the JTAG pins between JTAG and GPIO mode.
//
//*****************************************************************************
void
SysTickIntHandler(void)
{
unsigned char ucButtons;
unsigned char ucButtonsChanged;
//
// Grab the current, debounced state of the buttons.
//
ucButtons = ButtonsPoll(&ucButtonsChanged, 0);
//
// If the left button has been pressed, and was previously not pressed,
// start the process of changing the behavior of the JTAG pins.
//
if(BUTTON_PRESSED(LEFT_BUTTON, ucButtons, ucButtonsChanged))
{
//
// Toggle the pin mode.
//
g_ulMode ^= 1;
//
// See if the pins should be in JTAG or GPIO mode.
//
if(g_ulMode == 0)
{
//
// Change PC0-3 into hardware (i.e. JTAG) pins.
//
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x01;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) |= 0x01;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x02;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) |= 0x02;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x04;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) |= 0x04;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x08;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) |= 0x08;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x00;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = 0;
//
// Turn on the LED to indicate that the pins are in JTAG mode.
//
ROM_GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_3 | GPIO_PIN_1,
GPIO_PIN_3);
}
else
{
//
// Change PC0-3 into GPIO inputs.
//
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x01;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) &= 0xfe;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x02;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) &= 0xfd;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x04;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) &= 0xfb;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x08;
HWREG(GPIO_PORTC_BASE + GPIO_O_AFSEL) &= 0xf7;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY_DD;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x00;
HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = 0;
ROM_GPIOPinTypeGPIOInput(GPIO_PORTC_BASE, (GPIO_PIN_0 | GPIO_PIN_1 |
GPIO_PIN_2 | GPIO_PIN_3));
//
// Turn off the LED to indicate that the pins are in GPIO mode.
//
ROM_GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_3 | GPIO_PIN_1,
GPIO_PIN_1);
}
}
}
//*****************************************************************************
//
// Toggle the JTAG pins between JTAG and GPIO mode with a push button selecting
// between the two.
//
//*****************************************************************************
int
main(void)
{
unsigned long ulMode;
//
// 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_4 | SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ |
SYSCTL_OSC_MAIN);
//
// Enable the peripherals used by this application.
//
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
//
// Initialize the button driver.
//
ButtonsInit();
//
// Set up a SysTick Interrupt to handle polling and debouncing for our
// buttons.
//
SysTickPeriodSet(SysCtlClockGet() / 100);
SysTickIntEnable();
SysTickEnable();
IntMasterEnable();
//
// Configure the LED as an output and turn it on.
//
ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_3 | GPIO_PIN_1);
ROM_GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_3 | GPIO_PIN_1, GPIO_PIN_3);
//
// Set the global and local indicator of pin mode to zero, meaning JTAG.
//
g_ulMode = 0;
ulMode = 0;
//
// Initialize the UART.
//
GPIOPinConfigure(GPIO_PA0_U0RX);
GPIOPinConfigure(GPIO_PA1_U0TX);
ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
UARTStdioInit(0);
UARTprintf("\033[2JGPIO <-> JTAG\n");
//
// Indicate that the pins start out as JTAG.
//
UARTprintf("Pins are JTAG\n");
//
// Loop forever. This loop simply exists to display on the UART the
// current state of PC0-3; the handling of changing the JTAG pins to and
// from GPIO mode is done in GPIO Interrupt Handler.
//
while(1)
{
//
// Wait until the pin mode changes.
//
while(g_ulMode == ulMode)
{
}
//
// Save the new mode locally so that a subsequent pin mode change can
// be detected.
//
ulMode = g_ulMode;
//
// See what the new pin mode was changed to.
//
if(ulMode == 0)
{
//
// Indicate that PC0-3 are currently JTAG pins.
//
UARTprintf("Pins are JTAG\n");
}
else
{
//
// Indicate that PC0-3 are currently GPIO pins.
//
UARTprintf("Pins are GPIO\n");
}
}
}
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