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add pwm frequency to examples

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This commit is contained in:
rafael 2024-10-21 22:42:18 +02:00
parent 8dfc9ba1a3
commit 14e69309eb
3 changed files with 23 additions and 14 deletions
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10
examples/rp/src/bin/pwm.rs
View File

@ -45,8 +45,14 @@ async fn pwm_set_config(slice4: PWM_SLICE4, pin25: PIN_25) {
/// Using GP4 in Slice2, make sure to use an appropriate resistor.
#[embassy_executor::task]
async fn pwm_set_dutycycle(slice2: PWM_SLICE2, pin4: PIN_4) {
// If we aim for a specific frequency, here is how we can calculate the top value.
// The top value sets the period of the PWM cycle, so a counter goes from 0 to top and then wraps around to 0.
// Every such wraparound is one PWM cycle. So here is how we get 25KHz:
let mut c = Config::default();
c.top = 32_768;
let pwm_freq = 25_000; // Hz, our desired frequency
let clock_freq = embassy_rp::clocks::clk_sys_freq();
c.top = (clock_freq / pwm_freq) as u16 - 1;
let mut pwm = Pwm::new_output_a(slice2, pin4, c.clone());
loop {
@ -59,7 +65,7 @@ async fn pwm_set_dutycycle(slice2: PWM_SLICE2, pin4: PIN_4) {
Timer::after_secs(1).await;
// 25% duty cycle. Expressed as 32768/4 = 8192.
pwm.set_duty_cycle(8_192).unwrap();
pwm.set_duty_cycle(c.top / 4).unwrap();
Timer::after_secs(1).await;
// 0% duty cycle, fully off.

10
examples/rp23/src/bin/pwm.rs
View File

@ -50,8 +50,14 @@ async fn pwm_set_config(slice4: PWM_SLICE4, pin25: PIN_25) {
/// Using GP4 in Slice2, make sure to use an appropriate resistor.
#[embassy_executor::task]
async fn pwm_set_dutycycle(slice2: PWM_SLICE2, pin4: PIN_4) {
// If we aim for a specific frequency, here is how we can calculate the top value.
// The top value sets the period of the PWM cycle, so a counter goes from 0 to top and then wraps around to 0.
// Every such wraparound is one PWM cycle. So here is how we get 25KHz:
let mut c = Config::default();
c.top = 32_768;
let pwm_freq = 25_000; // Hz, our desired frequency
let clock_freq = embassy_rp::clocks::clk_sys_freq();
c.top = (clock_freq / pwm_freq) as u16 - 1;
let mut pwm = Pwm::new_output_a(slice2, pin4, c.clone());
loop {
@ -64,7 +70,7 @@ async fn pwm_set_dutycycle(slice2: PWM_SLICE2, pin4: PIN_4) {
Timer::after_secs(1).await;
// 25% duty cycle. Expressed as 32768/4 = 8192.
pwm.set_duty_cycle(8_192).unwrap();
pwm.set_duty_cycle(c.top / 4).unwrap();
Timer::after_secs(1).await;
// 0% duty cycle, fully off.

17
examples/rp23/src/bin/pwm_tb6612fng_motor_driver.rs
View File

@ -16,12 +16,6 @@ use embassy_time::{Duration, Timer};
use tb6612fng::{DriveCommand, Motor, Tb6612fng};
use {defmt_rtt as _, panic_probe as _};
/// Maximum PWM value (fully on)
const PWM_MAX: u16 = 50000;
/// Minimum PWM value (fully off)
const PWM_MIN: u16 = 0;
#[link_section = ".start_block"]
#[used]
pub static IMAGE_DEF: ImageDef = ImageDef::secure_exe();
@ -46,6 +40,11 @@ async fn main(_spawner: Spawner) {
let s = split_resources!(p);
let r = s.motor;
// we want a PWM frequency of 25KHz
let pwm_freq = 25_000; // Hz, our desired frequency
let clock_freq = embassy_rp::clocks::clk_sys_freq();
let period = (clock_freq / pwm_freq) as u16 - 1;
// we need a standby output and two motors to construct a full TB6612FNG
// standby pin
@ -55,8 +54,7 @@ async fn main(_spawner: Spawner) {
let left_fwd = gpio::Output::new(r.left_forward_pin, gpio::Level::Low);
let left_bckw = gpio::Output::new(r.left_backward_pin, gpio::Level::Low);
let mut left_speed = pwm::Config::default();
left_speed.top = PWM_MAX;
left_speed.compare_a = PWM_MIN;
left_speed.top = period;
let left_pwm = pwm::Pwm::new_output_a(r.left_slice, r.left_pwm_pin, left_speed);
let left_motor = Motor::new(left_fwd, left_bckw, left_pwm).unwrap();
@ -64,8 +62,7 @@ async fn main(_spawner: Spawner) {
let right_fwd = gpio::Output::new(r.right_forward_pin, gpio::Level::Low);
let right_bckw = gpio::Output::new(r.right_backward_pin, gpio::Level::Low);
let mut right_speed = pwm::Config::default();
right_speed.top = PWM_MAX;
right_speed.compare_b = PWM_MIN;
right_speed.top = period;
let right_pwm = pwm::Pwm::new_output_b(r.right_slice, r.right_pwm_pin, right_speed);
let right_motor = Motor::new(right_fwd, right_bckw, right_pwm).unwrap();