neorv32/sw/example/demo_pwm/main.c

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2024-02-24 08:25:27 +00:00
// #################################################################################################
// # << NEORV32 - PWM Demo Program >> #
// # ********************************************************************************************* #
// # BSD 3-Clause License #
// # #
// # Copyright (c) 2023, 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: #
// # #
// # 1. Redistributions of source code must retain the above copyright notice, this list of #
// # conditions and the following disclaimer. #
// # #
// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
// # conditions and the following disclaimer in the documentation and/or other materials #
// # provided with the distribution. #
// # #
// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
// # endorse or promote products derived from this software without specific prior written #
// # permission. #
// # #
// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
// # OF THE POSSIBILITY OF SUCH DAMAGE. #
// # ********************************************************************************************* #
// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
// #################################################################################################
/**********************************************************************//**
* @file demo_pwm/main.c
* @author Stephan Nolting
* @brief Simple PWM demo program.
**************************************************************************/
#include <neorv32.h>
/**********************************************************************//**
* @name User configuration
**************************************************************************/
/**@{*/
/** UART BAUD rate */
#define BAUD_RATE 19200
/** Maximum PWM output intensity (8-bit) */
#define PWM_MAX 200
/**@}*/
/**********************************************************************//**
* This program generates a simple dimming sequence for PWM channels 0 to 3.
*
* @note This program requires the PWM controller to be synthesized (the UART is optional).
*
* @return !=0 if error.
**************************************************************************/
int main() {
// 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()) {
// setup UART at default baud rate, no interrupts
neorv32_uart0_setup(BAUD_RATE, 0);
// say hello
neorv32_uart0_printf("<<< PWM demo program >>>\n");
}
// check if PWM unit is implemented at all
if (neorv32_pwm_available() == 0) {
if (neorv32_uart0_available()) {
neorv32_uart0_printf("ERROR: PWM module not implemented!\n");
}
return 1;
}
int num_pwm_channels = neorv32_pmw_get_num_channels();
// check number of PWM channels
if (neorv32_uart0_available()) {
neorv32_uart0_printf("Implemented PWM channels: %i\n\n", num_pwm_channels);
}
// deactivate all PWM channels
int i;
for (i=0; i<num_pwm_channels; i++) {
neorv32_pwm_set(i, 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) {
up = 0;
}
else {
pwm++;
}
}
else {
if (pwm == 0) {
ch = (ch + 1) & 3; // goto next channel
up = 1;
}
else {
pwm--;
}
}
neorv32_pwm_set(ch, pwm); // output new duty cycle
neorv32_cpu_delay_ms(3); // wait ~3ms
}
return 0;
}