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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) 2020, 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 200
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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 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_enable_debug_mode();
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// init UART at default baud rate, no rx interrupt, no tx interrupt
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neorv32_uart_setup(BAUD_RATE, 0, 0);
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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(5); // wait ~5ms
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}
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return 0;
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}
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