Implement a simple output voltage regulator
To be improved: inconsistent timing, very slow iteration time.
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parent
edf697d22b
commit
accfc73248
88
src/main.rs
88
src/main.rs
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@ -47,6 +47,9 @@ pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_GENERIC_03H;
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/// if your board has a different frequency
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const XTAL_FREQ_HZ: u32 = 12_000_000u32;
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const SWITCH_PWM_MAX: i32 = 512;
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const SWITCH_PWM_LIMIT: i32 = 93 * SWITCH_PWM_MAX / 100;
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fn convert_adc_measurements(raw: &[u16; 4]) -> (u32, u32, u32)
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{
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let iout = (raw[0] - raw[1]) as u32 * 3300 * 20 / 4096 / 28; // *20 = division by 50 mΩ shunt
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@ -119,14 +122,25 @@ fn main() -> ! {
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// Init PWMs
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let mut pwm_slices = hal::pwm::Slices::new(pac.PWM, &mut pac.RESETS);
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// Configure PWM4
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// Configure switch PWM
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let pwm5 = &mut pwm_slices.pwm5;
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pwm5.set_ph_correct();
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pwm5.set_div_int(4);
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pwm5.set_div_frac((88 << 4) / 100);
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pwm5.set_top(512);
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pwm5.set_top(SWITCH_PWM_MAX as u16);
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pwm5.enable();
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// set up switch PWM output
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// note:
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// duty cycle = 0 => output voltage = input voltage
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// duty cycle = 512 (100%) => input short circuit
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//
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// general: D = duty cycle (0..1)
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// => output voltage = 1/(1-D) * input voltage
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let pwr_switch_ch = &mut pwm5.channel_a;
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pwr_switch_ch.set_duty(0); // no output by default
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pwr_switch_ch.output_to(pins.gpio10);
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// LED pins
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let mut pin_led_r = pins.gpio13.into_push_pull_output();
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let mut pin_led_y = pins.gpio14.into_push_pull_output();
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@ -136,11 +150,6 @@ fn main() -> ! {
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pin_led_y.set_high().unwrap();
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pin_led_g.set_high().unwrap();
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// set up switch PWM
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let pwr_switch_ch = &mut pwm5.channel_a;
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pwr_switch_ch.output_to(pins.gpio10);
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pwr_switch_ch.set_duty(400);
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// SPI CS pin is controlled by software
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let mut spi_cs = pins.gpio5.into_push_pull_output();
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spi_cs.set_high().unwrap();
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@ -164,7 +173,19 @@ fn main() -> ! {
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uart.write_full_blocking(b"Initialization complete!\r\n");
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// Infinite loop, fading LED up and down
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let vtarget: i32 = 8000;
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const GAINSCALE: i32 = 10000;
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let pgain: i32 = 50;
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let igain: i32 = 100;
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let dgain: i32 = 0;
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let mut iaccu: i32 = 0;
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let mut elast: i32 = 0;
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const T: i32 = 1;
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// main loop
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loop {
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let mut adc_value: [u16; 4] = [0; 4];
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@ -175,6 +196,39 @@ fn main() -> ! {
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let (vin, vout, iout) = convert_adc_measurements(&adc_value);
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// PID controller
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let err: i32 = -(vout as i32 - vtarget);
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iaccu += igain * T * err;
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// limit iaccu
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if iaccu > SWITCH_PWM_LIMIT * GAINSCALE {
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iaccu = SWITCH_PWM_LIMIT * GAINSCALE;
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} else if iaccu < 0 {
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iaccu = 0;
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}
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let pval = pgain * err / GAINSCALE;
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let ival = iaccu / GAINSCALE;
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let dval = dgain * (err - elast) / GAINSCALE;
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elast = err;
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let ctrlout = pval + ival + dval;
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// limit the control value
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let pwmval;
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if ctrlout > SWITCH_PWM_LIMIT {
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pwmval = SWITCH_PWM_LIMIT;
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} else if ctrlout < 0 {
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pwmval = 0;
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} else {
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pwmval = ctrlout;
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}
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pwr_switch_ch.set_duty(pwmval as u16);
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{
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let mut data: String<16>;
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@ -199,7 +253,23 @@ fn main() -> ! {
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}
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}
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uart.write_full_blocking(b"]\r\n");
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uart.write_full_blocking(b"]; e=");
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data = String::from(err);
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uart.write_full_blocking(data.as_bytes());
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uart.write_full_blocking(b" => ");
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data = String::from(pval);
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uart.write_full_blocking(data.as_bytes());
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uart.write_full_blocking(b"+");
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data = String::from(ival);
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uart.write_full_blocking(data.as_bytes());
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uart.write_full_blocking(b"+");
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data = String::from(dval);
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uart.write_full_blocking(data.as_bytes());
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uart.write_full_blocking(b" = ");
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data = String::from(ctrlout);
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uart.write_full_blocking(data.as_bytes());
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uart.write_full_blocking(b"\r\n");
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}
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}
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}
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