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[/] [neorv32/] [trunk/] [sw/] [example/] [demo_pwm/] [main.c] - Blame information for rev 44

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// #################################################################################################
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// # << NEORV32 - PWM Demo Program >>                                                              #
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// # ********************************************************************************************* #
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// # BSD 3-Clause License                                                                          #
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// #                                                                                               #
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// # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #
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// #                                                                                               #
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// # Redistribution and use in source and binary forms, with or without modification, are          #
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// # permitted provided that the following conditions are met:                                     #
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// #                                                                                               #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of        #
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// #    conditions and the following disclaimer.                                                   #
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// #                                                                                               #
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// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of     #
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// #    conditions and the following disclaimer in the documentation and/or other materials        #
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// #    provided with the distribution.                                                            #
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// #                                                                                               #
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// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to  #
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// #    endorse or promote products derived from this software without specific prior written      #
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// #    permission.                                                                                #
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// #                                                                                               #
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// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS   #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF               #
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// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE    #
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// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,     #
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// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
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// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED    #
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// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING     #
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// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED  #
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// # OF THE POSSIBILITY OF SUCH DAMAGE.                                                            #
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// # ********************************************************************************************* #
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// # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #
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// #################################################################################################
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/**********************************************************************//**
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 * @file demo_pwm/main.c
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 * @author Stephan Nolting
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 * @brief Simple PWM usage example.
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 **************************************************************************/
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#include <neorv32.h>
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/**********************************************************************//**
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 * @name User configuration
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 **************************************************************************/
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/**@{*/
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/** UART BAUD rate */
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#define BAUD_RATE 19200
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/** Maximum PWM output intensity (0..255) */
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#define PWM_MAX 128
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/**@}*/
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/**********************************************************************//**
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 * This program generates a simple dimming sequence for PWM channel 0,1,2.
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 *
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 * @note This program requires the PWM controller to be synthesized (the UART is optional).
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 *
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 * @return Irrelevant.
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 **************************************************************************/
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int main() {
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  // check if PWM unit is implemented at all
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  if (neorv32_pwm_available() == 0) {
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    return 0;
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  }
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  // capture all exceptions and give debug info via UART
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  // this is not required, but keeps us safe
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  neorv32_rte_setup();
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  // init UART at default baud rate, no parity bits, no rx interrupt, no tx interrupt
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  neorv32_uart_setup(BAUD_RATE, 0b00, 0, 0);
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  // check available hardware extensions and compare with compiler flags
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  neorv32_rte_check_isa(0); // silent = 0 -> show message if isa mismatch
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  // say hello
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  neorv32_uart_print("PWM demo program\n");
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  // deativate all PWM channels
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  neorv32_pwm_set(0, 0);
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  neorv32_pwm_set(1, 0);
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  neorv32_pwm_set(2, 0);
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  neorv32_pwm_set(3, 0);
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  // configure and enable PWM
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  neorv32_pwm_setup(CLK_PRSC_64);
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  uint8_t pwm = 0;
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  uint8_t up = 1;
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  uint8_t ch = 0;
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  // animate!
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  while(1) {
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    // update duty cycle
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    if (up) {
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      if (pwm == (PWM_MAX & 0xFF)) {
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        up = 0;
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      }
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      else {
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        pwm++;
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      }
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    }
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    else {
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      if (pwm == 0) {
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        ch = (ch + 1) & 3; // goto next channel
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        up = 1;
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      }
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      else {
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        pwm--;
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      }
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    }
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    // output new duty cycle
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    if (ch != 3) { // skip channel 3
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      neorv32_pwm_set(ch, pwm);
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    }
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    neorv32_cpu_delay_ms(10); // wait ~10ms
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  }
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  return 0;
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}

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