//***************************************************************************** // // 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 //!

GPIO JTAG Recovery (gpio_jtag)

//! //! 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"); } } }