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// # << NEORV32 - General Purpose Timer (GPTMR) 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_gptmr/main.c

 * @author Stephan Nolting

 * @brief Simple GPTMR usage example.

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

#include <neorv32.h>

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

 * @name User configuration

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

/**@{*/

/** UART BAUD rate */

#define BAUD_RATE 19200

/**@}*/

// Prototypes

void gptmr_firq_handler(void);

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

 * This program blinks an LED at GPIO.output(0) at 1Hz using the general purpose timer interrupt.

 *

 * @note This program requires the GPTMR unit to be synthesized.

 *

 * @return Should not return;

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

int main() {

  // capture all exceptions and give debug info via UART

  neorv32_rte_setup();

  // init UART at default baud rate, no parity bits, ho hw flow control

  neorv32_uart0_setup(BAUD_RATE, PARITY_NONE, FLOW_CONTROL_NONE);

  // check if GPTMR unit is implemented at all

  if (neorv32_gptmr_available() == 0) {

    neorv32_uart0_print("General purpose timer not implemented!\n");

    return 1;

  }

  // Intro

  neorv32_uart0_print("General purpose timer (GPTMR) demo Program.\n"

                      "Toggles GPIO.output(0) at 1Hz using the GPTMR interrupt.\n\n");

  // clear GPIO output port

  neorv32_gpio_port_set(0);

  // install GPTMR interrupt handler

  neorv32_rte_exception_install(GPTMR_RTE_ID, gptmr_firq_handler);

  // configure timer for 1Hz in continuous mode

  uint32_t soc_clock = NEORV32_SYSINFO.CLK;

  soc_clock = soc_clock / 2; // divide by two as we are using the 1/2 clock prescaler

  neorv32_gptmr_setup(CLK_PRSC_2, 1, soc_clock);

  // enable interrupt

  neorv32_cpu_irq_enable(GPTMR_FIRQ_ENABLE); // enable GPTRM FIRQ channel

  neorv32_cpu_eint(); // enable global interrupt flag

  // do nothing, wait for interrupt

  while(1);

  return 0;

}

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

 * GPTMR FIRQ handler.

 *

 * @warning This function has to be of type "void xyz(void)" and must not use any interrupt attributes!

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

void gptmr_firq_handler(void) {

  neorv32_cpu_csr_write(CSR_MIP, 1<<GPTMR_FIRQ_PENDING); // clear/ack pending FIRQ

  neorv32_uart0_putc('.'); // send tick symbol via UART

  neorv32_gpio_pin_toggle(0); // toggle output port bit 0

}