M-Labs/thermostat
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Improve the VREF calibration routine

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* Fix wrong calibration of VREF on startup. Caused new v2.2.2 boards to
wrongly calibrate the zero-point to ~2.2 V instead of 1.5 V.

* Fix bootloop on some boards.

* Adjust watchdog interval accordingly.
This commit is contained in:
atse 2024-09-16 17:32:58 +08:00
parent c6040899dd
commit 1041d3ecbb
2 changed files with 5 additions and 14 deletions
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17
src/channels.rs
View File

@ -22,6 +22,7 @@ use crate::{
pins::{self, Channel0VRef, Channel1VRef},
steinhart_hart,
};
use crate::timer::sleep;
pub enum PinsAdcReadTarget {
VREF,
@ -269,17 +270,6 @@ impl Channels {
}
}
pub fn read_dac_feedback_until_stable(&mut self, channel: usize, tolerance: ElectricPotential) -> ElectricPotential {
let mut prev = self.adc_read(channel, PinsAdcReadTarget::DacVfb, 1);
loop {
let current = self.adc_read(channel, PinsAdcReadTarget::DacVfb, 1);
if (current - prev).abs() < tolerance {
return current;
}
prev = current;
}
}
/// Calibrates the DAC output to match vref of the MAX driver to reduce zero-current offset of the MAX driver output.
///
/// The thermostat DAC applies a control voltage signal to the CTLI pin of MAX driver chip to control its output current.
@ -306,7 +296,7 @@ impl Channels {
let mut start_value = 1;
let mut best_error = ElectricPotential::new::<volt>(100.0);
for step in (0..18).rev() {
for step in (5..18).rev() {
let mut prev_value = start_value;
for value in (start_value..=ad5680::MAX_VALUE).step_by(1 << step) {
match channel {
@ -318,8 +308,9 @@ impl Channels {
}
_ => unreachable!(),
}
sleep(10);
let dac_feedback = self.read_dac_feedback_until_stable(channel, ElectricPotential::new::<volt>(0.001));
let dac_feedback = self.adc_read(channel, PinsAdcReadTarget::DacVfb, 64);
let error = target_voltage - dac_feedback;
if error < ElectricPotential::new::<volt>(0.0) {
break;

2
src/main.rs
View File

@ -58,7 +58,7 @@ mod hw_rev;
const HSE: MegaHertz = MegaHertz(8);
#[cfg(not(feature = "semihosting"))]
const WATCHDOG_INTERVAL: u32 = 1_000;
const WATCHDOG_INTERVAL: u32 = 2_000;
#[cfg(feature = "semihosting")]
const WATCHDOG_INTERVAL: u32 = 30_000;