forked from M-Labs/thermostat
Disable feedback current readout on flawed HW Revs
Thermostats v2.2 and below have a noisy and offset feedback current `tec_i` caused by missing hardware on 2 MAX1968 TEC driver pins: 1. A missing RC filter on the ITEC pin that would have isolated CPU sampling pulses from the signal; and 2. Some missing buffering on the VREF pin that would have avoided loading the VREF signal, preventing voltage drops from the nominal 1.5V. Since the resulting signal `tec_i` derived from these two signals can have an error of around +/- 100mA, and readback may affect the stability performance of the Thermostat, disable current readback entirely on affected hardware revisions for now. See https://github.com/sinara-hw/Thermostat/issues/117 and https://github.com/sinara-hw/Thermostat/issues/120. On hardware revisions v3.x and above, this would be fixed.
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@ -271,6 +271,8 @@ with the following keys.
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| `tec_u_meas` | Volts | Measurement of the voltage across the TEC |
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| `pid_output` | Amperes | PID control output |
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Note: With Thermostat v2 and below, the voltage and current readouts `i_tec` and `tec_i` are disabled and null due to faulty hardware that introduces a lot of noise in the signal.
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## PID Tuning
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The thermostat implements a PID control loop for each of the TEC channels, more details on setting up the PID control loop can be found [here](./doc/PID%20tuning.md).
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@ -20,6 +20,7 @@ use crate::{
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command_handler::JsonBuffer,
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pins,
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steinhart_hart,
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hw_rev,
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};
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pub const CHANNELS: usize = 2;
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@ -28,17 +29,18 @@ pub const R_SENSE: f64 = 0.05;
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const DAC_OUT_V_MAX: f64 = 3.0;
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// TODO: -pub
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pub struct Channels {
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pub struct Channels<'a> {
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channel0: Channel<Channel0>,
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channel1: Channel<Channel1>,
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pub adc: ad7172::Adc<pins::AdcSpi, pins::AdcNss>,
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/// stm32f4 integrated adc
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pins_adc: pins::PinsAdc,
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pub pwm: pins::PwmPins,
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hwrev: &'a hw_rev::HWRev,
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}
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impl Channels {
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pub fn new(pins: pins::Pins) -> Self {
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impl<'a> Channels<'a> {
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pub fn new(pins: pins::Pins, hwrev: &'a hw_rev::HWRev) -> Self {
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let mut adc = ad7172::Adc::new(pins.adc_spi, pins.adc_nss).unwrap();
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// Feature not used
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adc.set_sync_enable(false).unwrap();
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@ -56,7 +58,7 @@ impl Channels {
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let channel1 = Channel::new(pins.channel1, adc_calibration1);
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let pins_adc = pins.pins_adc;
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let pwm = pins.pwm;
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let mut channels = Channels { channel0, channel1, adc, pins_adc, pwm };
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let mut channels = Channels { channel0, channel1, adc, pins_adc, pwm, hwrev };
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for channel in 0..CHANNELS {
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channels.calibrate_dac_value(channel);
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channels.set_i(channel, ElectricCurrent::new::<ampere>(0.0));
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@ -429,8 +431,8 @@ impl Channels {
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fn report(&mut self, channel: usize) -> Report {
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let i_set = self.get_i(channel);
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let i_tec = self.read_itec(channel);
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let tec_i = self.get_tec_i(channel);
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let i_tec = if self.hwrev.major > 2 {Some(self.read_itec(channel))} else {None};
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let tec_i = if self.hwrev.major > 2 {Some(self.get_tec_i(channel))} else {None};
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let dac_value = self.get_dac(channel);
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let state = self.channel_state(channel);
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let pid_output = ElectricCurrent::new::<ampere>(state.pid.y1);
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@ -543,8 +545,8 @@ pub struct Report {
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i_set: ElectricCurrent,
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dac_value: ElectricPotential,
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dac_feedback: ElectricPotential,
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i_tec: ElectricPotential,
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tec_i: ElectricCurrent,
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i_tec: Option<ElectricPotential>,
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tec_i: Option<ElectricCurrent>,
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tec_u_meas: ElectricPotential,
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pid_output: ElectricCurrent,
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}
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@ -138,7 +138,7 @@ fn main() -> ! {
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let mut store = flash_store::store(dp.FLASH);
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let mut channels = Channels::new(pins);
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let mut channels = Channels::new(pins, &hwrev);
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for c in 0..CHANNELS {
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match store.read_value::<ChannelConfig>(CHANNEL_CONFIG_KEY[c]) {
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Ok(Some(config)) =>
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