Subversion Repositories neorv32

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// # << NEORV32 - Watchdog Demo Program >>                                                         #

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// # BSD 3-Clause License                                                                          #

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// # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #

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// # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #

// #################################################################################################

/**********************************************************************//**

 * @file demo_wdt/main.c

 * @author Stephan Nolting

 * @brief Watchdog system reset demo program.

 **************************************************************************/

#include <neorv32.h>

/**********************************************************************//**

 * @name User configuration

 **************************************************************************/

/**@{*/

/** UART BAUD rate */

#define BAUD_RATE 19200

/**@}*/

/**********************************************************************//**

 * Main function

 *

 * @note This program requires the WDT and the UART to be synthesized.

 *

 * @return Irrelevant.

 **************************************************************************/

int main() {

  // check if WDT unit is implemented at all

  if (neorv32_wdt_available() == 0) {

    return 0; // nope, no WDT unit synthesized

  }

  // check if UART unit is implemented at all

  if (neorv32_uart_available() == 0) {

    return 0; // nope, no UART unit synthesized

  }

  // capture all exceptions and give debug info via UART

  // this is not required, but keeps us safe

  neorv32_rte_setup();

  // init UART at default baud rate, no parity bits, no rx interrupt, no tx interrupt

  neorv32_uart_setup(BAUD_RATE, 0b00, 0, 0);

  // check available hardware extensions and compare with compiler flags

  neorv32_rte_check_isa(0); // silent = 0 -> show message if isa mismatch

  // simple text output via UART (strings only)

  neorv32_uart_print("\nWatchdog system reset demo program\n\n");

  // show the cause of the last processor reset

  neorv32_uart_print("Cause of last processor reset: ");

  uint8_t wdt_cause = neorv32_wdt_get_cause();

  if (wdt_cause == 0) {

    neorv32_uart_print("External reset\n");

  }

  else if (wdt_cause == 1) {

    neorv32_uart_print("Watchdog\n");

  }

  else {

    neorv32_uart_print("Undefined\n");

  }

  // the watchod has a 20-bit counter, which triggers either an interrupt or a system reset

  // when overflowing

  // init watchdog (watchdog timer increment = cpu_clock/64, trigger reset on overflow, lock

  // access so nobody can alter the configuration until next reset)

  neorv32_wdt_setup(CLK_PRSC_64, 1, 1);

  neorv32_uart_print("\n\nWill reset WDT 64 times.\n"

                     "A system reset will be executed in the following time out.\n"

                     "Press any key to trigger manual WDT hardware reset by WDT access with wrong password.\n"

                     "Restart this program after reset to check for the reset cause.\n\n"

                     "WDT resets: ");

  uint8_t i;

  for (i=0; i<64; i++) {

    neorv32_uart_putc('.');

    neorv32_wdt_reset(); // reset watchdog

    neorv32_cpu_delay_ms(80); // wait some time

    // trigger manual reset if key pressed

    if (neorv32_uart_char_received()) { // just check, if a char has been received

      neorv32_wdt_force(); // access wdt with wrong password

    }

  }

  while (1) { // wait for the watchdog time-out or trigger manual reset if key pressed

    if (neorv32_uart_char_received()) { // just check, if a char has been received

      neorv32_wdt_force(); // access wdt with wrong password

    }

  }

  return 0;

}