Subversion Repositories neorv32

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

// # << NEORV32 - PWM 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_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;

}