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// #################################################################################################
// # << NEORV32 - General Purpose Timer (GPTMR) Demo Program >>                                    #
// # ********************************************************************************************* #
// # BSD 3-Clause License                                                                          #
// #                                                                                               #
// # 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
}