Subversion Repositories neorv32

// #################################################################################################
// # << NEORV32 - PWM Demo Program >>                                                              #
// # ********************************************************************************************* #
// # BSD 3-Clause License                                                                          #
// #                                                                                               #
// # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #
// #                                                                                               #
// # Redistribution and use in source and binary forms, with or without modification, are          #
// # permitted provided that the following conditions are met:                                     #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of        #
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// #    permission.                                                                                #
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// # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #
// #################################################################################################
 
 
/**********************************************************************//**
 * @file demo_pwm/main.c
 * @author Stephan Nolting
 * @brief Simple PWM usage example.
 **************************************************************************/
 
#include <neorv32.h>
 
 
/**********************************************************************//**
 * @name User configuration
 **************************************************************************/
/**@{*/
/** UART BAUD rate */
#define BAUD_RATE 19200
/** Maximum PWM output intensity (0..255) */
#define PWM_MAX 128
/**@}*/
 
 
/**********************************************************************//**
 * This program generates a simple dimming sequence for PWM channel 0,1,2.
 *
 * @note This program requires the PWM controller to be synthesized (the UART is optional).
 *
 * @return 0 if execution was successful
 **************************************************************************/
int main() {
 
  // check if PWM unit is implemented at all
  if (neorv32_pwm_available() == 0) {
    return 1;
  }
 
 
  // capture all exceptions and give debug info via UART
  // this is not required, but keeps us safe
  neorv32_rte_setup();
 
  // use UART0 if implemented
  if (neorv32_uart0_available()) {
    // init UART at default baud rate, no parity bits, ho hw flow control
    neorv32_uart0_setup(BAUD_RATE, PARITY_NONE, FLOW_CONTROL_NONE);
 
    // check available hardware extensions and compare with compiler flags
    neorv32_rte_check_isa(0); // silent = 0 -> show message if isa mismatch
 
    // say hello
    neorv32_uart0_print("PWM demo program\n");
  }
 
 
  // deactivate all PWM channels
  neorv32_pwm_set(0, 0);
  neorv32_pwm_set(1, 0);
  neorv32_pwm_set(2, 0);
  neorv32_pwm_set(3, 0);
 
  // configure and enable PWM
  neorv32_pwm_setup(CLK_PRSC_64);
 
 
  uint8_t pwm = 0;
  uint8_t up = 1;
  uint8_t ch = 0;
 
  // animate!
  while(1) {
 
    // update duty cycle
    if (up) {
      if (pwm == (PWM_MAX & 0xFF)) {
        up = 0;
      }
      else {
        pwm++;
      }
    }
    else {
      if (pwm == 0) {
        ch = (ch + 1) & 3; // goto next channel
        up = 1;
      }
      else {
        pwm--;
      }
    }
 
    // output new duty cycle
    if (ch != 3) { // skip channel 3
      neorv32_pwm_set(ch, pwm);
    }
 
    neorv32_cpu_delay_ms(10); // wait ~10ms
  }
 
  return 0;
}