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refactor(PWM): 

Modified for a more space optimised PWM function
This commit is contained in:
Devoalda 2023-09-18 09:19:33 +08:00
parent 3813bf38f4
commit 02eb68208c
1 changed files with 5 additions and 45 deletions
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50
lab_4/lab_4.c
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@ -15,8 +15,6 @@
#include "hardware/adc.h"
#define PWM_PIN 2
#define PWM_FREQ 20
#define PWM_DUTY 50
#define ADC_PIN 26
#define ADC_FREQ 25
@ -41,48 +39,6 @@ bool repeating_timer_callback (struct repeating_timer *t) {
return true;
}
/**
* Helper function to calculate the clock divider and wrap value for PWM
* Based on: https://www.i-programmer.info/programming/hardware/14849-the-pico-in-c-basic-pwm.html
*
* RP2040 clock is 125 MHz, PWM Counter is 16-bit
* Clock divider is 16-bit, with 12-bit integer and 4-bit fraction
* @param slice_num PWM slice number
* @param channel PWM channel
* @param frequency PWM frequency
* @param duty_cycle PWM duty cycle
* @return PWM wrap value
*/
uint32_t pwm_set_freq_duty (uint slice_num,
uint channel, uint32_t frequency, int duty_cycle) {
uint32_t clock = 125000000;
// divider = Ceil(16 * clock / 65536 * frequency) + remainder
// = Ceil(clock / frequency / 4096) + remainder
uint32_t divider16 = clock / frequency / 4096 +
(clock % (frequency * 4096) !=
0); // Round up if less than 1
// If divider is less than 16, set it to 16 (16-bit counter)
if (divider16 / 16 == 0)
{
divider16 = 16;
}
// Wrap value is 16 bits, so max value is 65535 (2^16 - 1)
uint32_t wrap = clock * 16 / divider16 / frequency - 1;
// Set clock divider and wrap value
pwm_set_clkdiv_int_frac(slice_num, divider16 / 16,
divider16 & 0xF);
pwm_set_wrap(slice_num, wrap);
// Level = wrap * duty_cycle(as fraction)
// = wrap * duty_cycle / 100
pwm_set_chan_level(slice_num, channel, wrap * duty_cycle / 100);
return wrap;
}
/**
* Setup Function for PWM and ADC
* @param timer Repeating timer for ADC
@ -92,7 +48,11 @@ void setup (struct repeating_timer *timer) {
gpio_set_function(PWM_PIN, GPIO_FUNC_PWM);
uint slice_num = pwm_gpio_to_slice_num(PWM_PIN);
uint channel = pwm_gpio_to_channel(PWM_PIN);
pwm_set_freq_duty(slice_num, channel, PWM_FREQ, PWM_DUTY);
pwm_set_clkdiv(slice_num, 100); // 125 MHz / 100 = 1.25 MHz
pwm_set_wrap(slice_num, 62500); // 1.25 MHz / 62500 = 20 Hz
pwm_set_chan_level(slice_num, channel, 62500/2); // 50% duty cycle
pwm_set_enabled(slice_num, true);
// ADC setup