add swap status to the report

Signed-off-by: Egor Savkin <es@m-labs.hk>

.gitignore

@@ -1,5 +1,2 @@
 target/
 result
-*.bin
-
-__pycache__/

README.md

@@ -45,7 +45,7 @@ There are several options for flashing Thermostat. DFU requires only a micro-USB
 
 ### dfu-util on Linux
 * Install the DFU USB tool (dfu-util).
-* Convert firmware from ELF to BIN: `llvm-objcopy -O binary target/thumbv7em-none-eabihf/release/thermostat thermostat.bin` (you can skip this step if using the BIN from Hydra)
+* Convert firmware from ELF to BIN: `arm-none-eabi-objcopy -O binary thermostat thermostat.bin` (you can skip this step if using the BIN from Hydra)
 * Connect to the Micro USB connector to Thermostat below the RJ45.
 * Add jumper to Thermostat v2.0 across 2-pin jumper adjacent to JTAG connector.
 * Cycle board power to put it in DFU update mode
@@ -95,7 +95,7 @@ Send commands as simple text string terminated by `\n`. Responses are
 formatted as line-delimited JSON.
 
 | Syntax                           | Function                                                                      |
-|-------------------------------------------|-------------------------------------------------------------------------------|
+|----------------------------------|-------------------------------------------------------------------------------|
 | `report`                         | Show current input                                                            |
 | `report mode`                    | Show current report mode                                                      |
 | `report mode <off/on>`           | Set report mode                                                               |
@@ -104,7 +104,6 @@ formatted as line-delimited JSON.
 | `pwm <0/1> max_i_neg <amp>`      | Set maximum negative output current                                           |
 | `pwm <0/1> max_v <volt>`         | Set maximum output voltage                                                    |
 | `pwm <0/1> i_set <amp>`          | Disengage PID, set fixed output current                                       |
-| `pwm <0/1> polarity_swapped <false/true>` | Swap output current polarity on channel                                       |
 | `pwm <0/1> pid`                  | Let output current to be controlled by the PID                                |
 | `center <0/1> <volt>`            | Set the MAX1968 0A-centerpoint to the specified fixed voltage                 |
 | `center <0/1> vref`              | Set the MAX1968 0A-centerpoint to measure from VREF                           |
@@ -131,6 +130,7 @@ formatted as line-delimited JSON.
 | `fcurve <a> <b> <c>`             | Set fan controller curve coefficients (see *Fan control* section)             |
 | `fcurve default`                 | Set fan controller curve coefficients to defaults (see *Fan control* section) |
 | `hwrev`                          | Show hardware revision, and settings related to it                            |
+| `swap [0/1]`                     | Swap TEC polarities for channel all/0/1 (For use with Zotino)                 |
 
 
 ## USB
@@ -181,9 +181,11 @@ postfilter rate can be tuned with the `postfilter` command.
 
 ## Thermo-Electric Cooling (TEC)
 
-- Connect TEC module device 0 to TEC0- and TEC0+.
-- Connect TEC module device 1 to TEC1- and TEC1+.
-- The GND pin is for shielding not for sinking TEC module currents.
+- Connect TEC module device 0 to TEC0-/T0- and TEC0+/T0+.
+- Connect TEC module device 1 to TEC1-/T1- and TEC1+/T1+.
+- The GND pin is for shielding, not for sinking TEC module currents.
+
+For Zotino temperature regulation, connect an IDC cable to the internal Zotino header labeled TEC1/TEC2. For pre 3.0 Thermostats, use the `swap` command for those channels.
 
 When using a TEC module with the Thermostat, the Thermostat expects the thermal load (where the thermistor is located) to cool down with a positive software current set point, and heat up with a negative current set point.
 
@@ -272,7 +274,7 @@ with the following keys.
 | `tec_u_meas`   | Volts           | Measurement of the voltage across the TEC            |
 | `pid_output`   | Amperes         | PID control output                                   |
 
-Note: With Thermostat v2 and below, the voltage and current readouts `i_tec` and `tec_i` are noisy without the hardware fix shown in [this PR][https://git.m-labs.hk/M-Labs/thermostat/pulls/105].
+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.
 
 ## PID Tuning
 

flake.lock

@@ -1,45 +1,41 @@
 {
   "nodes": {
+    "mozilla-overlay": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1690536331,
+        "narHash": "sha256-aRIf2FB2GTdfF7gl13WyETmiV/J7EhBGkSWXfZvlxcA=",
+        "owner": "mozilla",
+        "repo": "nixpkgs-mozilla",
+        "rev": "db89c8707edcffefcd8e738459d511543a339ff5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "mozilla",
+        "repo": "nixpkgs-mozilla",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1722791413,
-        "narHash": "sha256-rCTrlCWvHzMCNcKxPE3Z/mMK2gDZ+BvvpEVyRM4tKmU=",
+        "lastModified": 1691421349,
+        "narHash": "sha256-RRJyX0CUrs4uW4gMhd/X4rcDG8PTgaaCQM5rXEJOx6g=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "8b5b6723aca5a51edf075936439d9cd3947b7b2c",
+        "rev": "011567f35433879aae5024fc6ec53f2a0568a6c4",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-24.05",
+        "ref": "nixos-23.05",
         "repo": "nixpkgs",
         "type": "github"
       }
     },
     "root": {
       "inputs": {
-        "nixpkgs": "nixpkgs",
-        "rust-overlay": "rust-overlay"
-      }
-    },
-    "rust-overlay": {
-      "inputs": {
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1719281921,
-        "narHash": "sha256-LIBMfhM9pMOlEvBI757GOK5l0R58SRi6YpwfYMbf4yc=",
-        "owner": "oxalica",
-        "repo": "rust-overlay",
-        "rev": "b6032d3a404d8a52ecfc8571ff0c26dfbe221d07",
-        "type": "github"
-      },
-      "original": {
-        "owner": "oxalica",
-        "repo": "rust-overlay",
-        "type": "github"
+        "mozilla-overlay": "mozilla-overlay",
+        "nixpkgs": "nixpkgs"
       }
     }
   },

flake.nix

@@ -1,25 +1,32 @@
 {
   description = "Firmware for the Sinara 8451 Thermostat";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
-  inputs.rust-overlay = { 
-    url = "github:oxalica/rust-overlay";
-    inputs.nixpkgs.follows = "nixpkgs";
-  };
+  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-23.05;
+  inputs.mozilla-overlay = { url = github:mozilla/nixpkgs-mozilla; flake = false; };
 
-  outputs = { self, nixpkgs, rust-overlay }:
+  outputs = { self, nixpkgs, mozilla-overlay }:
     let
-      pkgs = import nixpkgs { system = "x86_64-linux"; overlays = [ (import rust-overlay) ]; };
-
-      rust = pkgs.rust-bin.stable."1.66.0".default.override {
-        extensions = [ "rust-src" ];
-        targets = [ "thumbv7em-none-eabihf" ];
+      pkgs = import nixpkgs { system = "x86_64-linux"; overlays = [ (import mozilla-overlay) ]; };
+      rustManifest = pkgs.fetchurl {
+        url = "https://static.rust-lang.org/dist/2022-12-15/channel-rust-stable.toml";
+        hash = "sha256-S7epLlflwt0d1GZP44u5Xosgf6dRrmr8xxC+Ml2Pq7c=";
       };
-      rustPlatform = pkgs.makeRustPlatform {
+
+      targets = [
+        "thumbv7em-none-eabihf"
+      ];
+      rustChannelOfTargets = _channel: _date: targets:
+        (pkgs.lib.rustLib.fromManifestFile rustManifest {
+          inherit (pkgs) stdenv lib fetchurl patchelf;
+          }).rust.override {
+          inherit targets;
+          extensions = ["rust-src"];
+        };
+      rust = rustChannelOfTargets "stable" null targets;
+      rustPlatform = pkgs.recurseIntoAttrs (pkgs.makeRustPlatform {
         rustc = rust;
         cargo = rust;
-      };
-
+      });
       thermostat = rustPlatform.buildRustPackage {
         name = "thermostat";
         version = "0.0.0";
@@ -47,26 +54,24 @@
         '';
 
         dontFixup = true;
-        auditable = false;
       };
     in {
       packages.x86_64-linux = {
         inherit thermostat;
-        default = thermostat;
       };
 
       hydraJobs = {
         inherit thermostat;
       };
 
-      devShells.x86_64-linux.default = pkgs.mkShellNoCC {
+      devShell.x86_64-linux = pkgs.mkShell {
         name = "thermostat-dev-shell";
-        packages = with pkgs; [
-          rust llvm
-          openocd dfu-util rlwrap
+        buildInputs = with pkgs; [
+          rust openocd dfu-util
           ] ++ (with python3Packages; [
             numpy matplotlib
           ]);
       };
+      defaultPackage.x86_64-linux = thermostat;
     };
 }

src/channel.rs

@@ -24,7 +24,7 @@ pub struct Channel<C: ChannelPins> {
     pub vref_meas: ElectricPotential,
     pub shdn: C::Shdn,
     pub vref_pin: C::VRefPin,
-    pub itec_pin: C::ITecPin,
+    pub itec_pin: C::ItecPin,
     /// feedback from `dac` output
     pub dac_feedback_pin: C::DacFeedbackPin,
     pub tec_u_meas_pin: C::TecUMeasPin,

src/channel_state.rs

@@ -35,7 +35,7 @@ pub struct ChannelState {
     pub pid_engaged: bool,
     pub pid: pid::Controller,
     pub sh: sh::Parameters,
-    pub polarity_swapped: bool,
+    pub swap_tec_polarity: bool,
 }
 
 impl ChannelState {
@@ -52,7 +52,7 @@ impl ChannelState {
             pid_engaged: false,
             pid: pid::Controller::new(pid::Parameters::default()),
             sh: sh::Parameters::default(),
-            polarity_swapped: false,
+            swap_tec_polarity: false,
         }
     }
 

src/channels.rs

@@ -1,6 +1,5 @@
-use core::marker::PhantomData;
+use core::cmp::max_by;
 use heapless::{consts::U2, Vec};
-use num_traits::Zero;
 use serde::{Serialize, Serializer};
 use smoltcp::time::Instant;
 use stm32f4xx_hal::hal;
@@ -21,53 +20,31 @@ use crate::{
     command_handler::JsonBuffer,
     pins::{self, Channel0VRef, Channel1VRef},
     steinhart_hart,
+    hw_rev,
 };
-use crate::timer::sleep;
-
-pub enum PinsAdcReadTarget {
-    VREF,
-    DacVfb,
-    ITec,
-    VTec,
-}
 
 pub const CHANNELS: usize = 2;
 pub const R_SENSE: f64 = 0.05;
 
-// From design specs
-pub const MAX_TEC_I: ElectricCurrent = ElectricCurrent {
-    dimension: PhantomData,
-    units: PhantomData,
-    value: 2.0,
-};
-pub const MAX_TEC_V: ElectricPotential = ElectricPotential {
-    dimension: PhantomData,
-    units: PhantomData,
-    value: 4.0,
-};
-const MAX_TEC_I_DUTY_TO_CURRENT_RATE: ElectricCurrent = ElectricCurrent {
-    dimension: PhantomData,
-    units: PhantomData,
-    value: 1.0 / (10.0 * R_SENSE / 3.3),
-};
+// as stated in the MAX1968 datasheet
+pub const MAX_TEC_I: f64 = 3.0;
+
 // DAC chip outputs 0-5v, which is then passed through a resistor dividor to provide 0-3v range
-const DAC_OUT_V_MAX: ElectricPotential = ElectricPotential {
-    dimension: PhantomData,
-    units: PhantomData,
-    value: 3.0,
-};
+const DAC_OUT_V_MAX: f64 = 3.0;
+
 // TODO: -pub
-pub struct Channels {
+pub struct Channels<'a> {
     channel0: Channel<Channel0>,
     channel1: Channel<Channel1>,
     pub adc: ad7172::Adc<pins::AdcSpi, pins::AdcNss>,
     /// stm32f4 integrated adc
     pins_adc: pins::PinsAdc,
     pub pwm: pins::PwmPins,
+    hwrev: &'a hw_rev::HWRev,
 }
 
-impl Channels {
-    pub fn new(pins: pins::Pins) -> Self {
+impl<'a> Channels<'a> {
+    pub fn new(pins: pins::Pins, hwrev: &'a hw_rev::HWRev) -> Self {
         let mut adc = ad7172::Adc::new(pins.adc_spi, pins.adc_nss).unwrap();
         // Feature not used
         adc.set_sync_enable(false).unwrap();
@@ -85,7 +62,7 @@ impl Channels {
         let channel1 = Channel::new(pins.channel1, adc_calibration1);
         let pins_adc = pins.pins_adc;
         let pwm = pins.pwm;
-        let mut channels = Channels { channel0, channel1, adc, pins_adc, pwm };
+        let mut channels = Channels { channel0, channel1, adc, pins_adc, pwm, hwrev };
         for channel in 0..CHANNELS {
             channels.calibrate_dac_value(channel);
             channels.set_i(channel, ElectricCurrent::new::<ampere>(0.0));
@@ -127,7 +104,7 @@ impl Channels {
     pub fn get_center(&mut self, channel: usize) -> ElectricPotential {
         match self.channel_state(channel).center {
             CenterPoint::Vref =>
-                self.adc_read(channel, PinsAdcReadTarget::VREF, 8),
+                self.read_vref(channel),
             CenterPoint::Override(center_point) =>
                 ElectricPotential::new::<volt>(center_point.into()),
         }
@@ -141,12 +118,16 @@ impl Channels {
 
     pub fn get_i(&mut self, channel: usize) -> ElectricCurrent {
         let i_set = self.channel_state(channel).i_set;
+        if self.channel_state(channel).swap_tec_polarity {
+            -i_set
+        } else {
             i_set
         }
+    }
 
     /// i_set DAC
     fn set_dac(&mut self, channel: usize, voltage: ElectricPotential) -> ElectricPotential {
-        let value = ((voltage / DAC_OUT_V_MAX).get::<ratio>() * (ad5680::MAX_VALUE as f64)) as u32 ;
+        let value = ((voltage / ElectricPotential::new::<volt>(DAC_OUT_V_MAX)).get::<ratio>() * (ad5680::MAX_VALUE as f64)) as u32 ;
         match channel {
             0 => self.channel0.dac.set(value).unwrap(),
             1 => self.channel1.dac.set(value).unwrap(),
@@ -157,123 +138,135 @@ impl Channels {
     }
 
     pub fn set_i(&mut self, channel: usize, i_set: ElectricCurrent) -> ElectricCurrent {
-        let mut i_set = i_set.min(MAX_TEC_I).max(-MAX_TEC_I);
-        self.channel_state(channel).i_set = i_set;
-        if self.channel_state(channel).polarity_swapped {
-            i_set = -i_set;
-        }
+        // Silently clamp i_set
+        let i_ceiling = ElectricCurrent::new::<ampere>(MAX_TEC_I);
+        let i_floor = ElectricCurrent::new::<ampere>(-MAX_TEC_I);
+        let mut i_set = i_set.min(i_ceiling).max(i_floor);
+
         let vref_meas = match channel.into() {
             0 => self.channel0.vref_meas,
             1 => self.channel1.vref_meas,
             _ => unreachable!(),
         };
+        if self.channel_state(channel).swap_tec_polarity {
+            i_set = -i_set;
+        }
         let center_point = vref_meas;
         let r_sense = ElectricalResistance::new::<ohm>(R_SENSE);
         let voltage = i_set * 10.0 * r_sense + center_point;
         let voltage = self.set_dac(channel, voltage);
         let i_set = (voltage - center_point) / (10.0 * r_sense);
+        self.channel_state(channel).i_set = i_set;
         i_set
     }
 
-    /// AN4073: ADC Reading Dispersion can be reduced through Averaging
-    pub fn adc_read(&mut self, channel: usize, adc_read_target: PinsAdcReadTarget, avg_pt: u16) -> ElectricPotential {
-        let mut sample: u32 = 0;
+    pub fn read_dac_feedback(&mut self, channel: usize) -> ElectricPotential {
         match channel {
             0 => {
-                sample = match adc_read_target {
-                    PinsAdcReadTarget::VREF => {
-                        match &self.channel0.vref_pin {
-                            Channel0VRef::Analog(vref_pin) => {
-                                for _ in (0..avg_pt).rev() {
-                                    sample += self
-                                        .pins_adc
-                                        .convert(vref_pin, stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                        as u32;
-                                }
-                                sample / avg_pt as u32
-                            },
-                            Channel0VRef::Disabled(_) => {2048 as u32}
-                        }
-                    }
-                    PinsAdcReadTarget::DacVfb => {
-                        for _ in (0..avg_pt).rev() {
-                            sample += self
-                                .pins_adc
-                                .convert(&self.channel0.dac_feedback_pin,stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                as u32;
-                        }
-                        sample / avg_pt as u32
-                    }
-                    PinsAdcReadTarget::ITec => {
-                        for _ in (0..avg_pt).rev() {
-                            sample += self
-                                .pins_adc
-                                .convert(&self.channel0.itec_pin, stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                as u32;
-                        }
-                        sample / avg_pt as u32
-                    }
-                    PinsAdcReadTarget::VTec => {
-                        for _ in (0..avg_pt).rev() {
-                            sample += self
-                                .pins_adc
-                                .convert(&self.channel0.tec_u_meas_pin, stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                as u32;
-                        }
-                        sample / avg_pt as u32
-                    }
-                };
-                let mv = self.pins_adc.sample_to_millivolts(sample as u16);
+                let sample = self.pins_adc.convert(
+                    &self.channel0.dac_feedback_pin,
+                    stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                );
+                let mv = self.pins_adc.sample_to_millivolts(sample);
                 ElectricPotential::new::<millivolt>(mv as f64)
             }
             1 => {
-                sample = match adc_read_target {
-                    PinsAdcReadTarget::VREF => {
-                        match &self.channel1.vref_pin {
-                            Channel1VRef::Analog(vref_pin) => {
-                                for _ in (0..avg_pt).rev() {
-                                    sample += self
-                                        .pins_adc
-                                        .convert(vref_pin, stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                        as u32;
-                                }
-                                sample / avg_pt as u32
-                            },
-                            Channel1VRef::Disabled(_) => {2048 as u32}
-                        }
-                    }
-                    PinsAdcReadTarget::DacVfb => {
-                        for _ in (0..avg_pt).rev() {
-                            sample += self
-                                .pins_adc
-                                .convert(&self.channel1.dac_feedback_pin, stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                as u32;
-                        }
-                        sample / avg_pt as u32
-                    }
-                    PinsAdcReadTarget::ITec => {
-                        for _ in (0..avg_pt).rev() {
-                            sample += self
-                                .pins_adc
-                                .convert(&self.channel1.itec_pin, stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                as u32;
-                        }
-                        sample / avg_pt as u32
-                    }
-                    PinsAdcReadTarget::VTec => {
-                        for _ in (0..avg_pt).rev() {
-                            sample += self
-                                .pins_adc
-                                .convert(&self.channel1.tec_u_meas_pin, stm32f4xx_hal::adc::config::SampleTime::Cycles_480)
-                                as u32;
-                        }
-                        sample / avg_pt as u32
-                    }
-                };
-                let mv = self.pins_adc.sample_to_millivolts(sample as u16);
+                let sample = self.pins_adc.convert(
+                    &self.channel1.dac_feedback_pin,
+                    stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                );
+                let mv = self.pins_adc.sample_to_millivolts(sample);
                 ElectricPotential::new::<millivolt>(mv as f64)
             }
-            _ => unreachable!()
+            _ => unreachable!(),
+        }
+    }
+
+    pub fn read_dac_feedback_until_stable(&mut self, channel: usize, tolerance: ElectricPotential) -> ElectricPotential {
+        let mut prev = self.read_dac_feedback(channel);
+        loop {
+            let current = self.read_dac_feedback(channel);
+            if (current - prev).abs() < tolerance {
+                return current;
+            }
+            prev = current;
+        }
+    }
+
+    pub fn read_itec(&mut self, channel: usize) -> ElectricPotential {
+        match channel {
+            0 => {
+                let sample = self.pins_adc.convert(
+                    &self.channel0.itec_pin,
+                    stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                );
+                let mv = self.pins_adc.sample_to_millivolts(sample);
+                ElectricPotential::new::<millivolt>(mv as f64)
+            }
+            1 => {
+                let sample = self.pins_adc.convert(
+                    &self.channel1.itec_pin,
+                    stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                );
+                let mv = self.pins_adc.sample_to_millivolts(sample);
+                ElectricPotential::new::<millivolt>(mv as f64)
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    /// should be 1.5V
+    pub fn read_vref(&mut self, channel: usize) -> ElectricPotential {
+        match channel {
+            0 => {
+                match &self.channel0.vref_pin {
+                    Channel0VRef::Analog(vref_pin) => {
+                        let sample = self.pins_adc.convert(
+                            vref_pin,
+                            stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                        );
+                        let mv = self.pins_adc.sample_to_millivolts(sample);
+                        ElectricPotential::new::<millivolt>(mv as f64)
+                    },
+                    Channel0VRef::Disabled(_) => ElectricPotential::new::<volt>(1.5)
+                }
+            }
+            1 => {
+                match &self.channel1.vref_pin {
+                    Channel1VRef::Analog(vref_pin) => {
+                        let sample = self.pins_adc.convert(
+                            vref_pin,
+                            stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                        );
+                        let mv = self.pins_adc.sample_to_millivolts(sample);
+                        ElectricPotential::new::<millivolt>(mv as f64)
+                    },
+                    Channel1VRef::Disabled(_) => ElectricPotential::new::<volt>(1.5)
+                }
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    pub fn read_tec_u_meas(&mut self, channel: usize) -> ElectricPotential {
+        match channel {
+            0 => {
+                let sample = self.pins_adc.convert(
+                    &self.channel0.tec_u_meas_pin,
+                    stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                );
+                let mv = self.pins_adc.sample_to_millivolts(sample);
+                ElectricPotential::new::<millivolt>(mv as f64)
+            }
+            1 => {
+                let sample = self.pins_adc.convert(
+                    &self.channel1.tec_u_meas_pin,
+                    stm32f4xx_hal::adc::config::SampleTime::Cycles_480
+                );
+                let mv = self.pins_adc.sample_to_millivolts(sample);
+                ElectricPotential::new::<millivolt>(mv as f64)
+            }
+            _ => unreachable!(),
         }
     }
 
@@ -303,7 +296,8 @@ impl Channels {
         let mut start_value = 1;
         let mut best_error = ElectricPotential::new::<volt>(100.0);
 
-        for step in (5..18).rev() {
+        for step in (0..18).rev() {
+            let mut prev_value = start_value;
             for value in (start_value..=ad5680::MAX_VALUE).step_by(1 << step) {
                 match channel {
                     0 => {
@@ -314,23 +308,24 @@ impl Channels {
                     }
                     _ => unreachable!(),
                 }
-                sleep(10);
 
-                let dac_feedback = self.adc_read(channel, PinsAdcReadTarget::DacVfb, 64);
+                let dac_feedback = self.read_dac_feedback_until_stable(channel, ElectricPotential::new::<volt>(0.001));
                 let error = target_voltage - dac_feedback;
                 if error < ElectricPotential::new::<volt>(0.0) {
                     break;
                 } else if error < best_error {
                     best_error = error;
-                    start_value = value;
+                    start_value = prev_value;
 
-                    let vref = (value as f64 / ad5680::MAX_VALUE as f64) * DAC_OUT_V_MAX;
+                    let vref = (value as f64 / ad5680::MAX_VALUE as f64) * ElectricPotential::new::<volt>(DAC_OUT_V_MAX);
                     match channel {
                         0 => self.channel0.vref_meas = vref,
                         1 => self.channel1.vref_meas = vref,
                         _ => unreachable!(),
                     }
                 }
+
+                prev_value = value;
             }
         }
 
@@ -382,26 +377,28 @@ impl Channels {
         }
     }
 
-    pub fn get_max_v(&mut self, channel: usize) -> (ElectricPotential, ElectricPotential) {
+    pub fn get_max_v(&mut self, channel: usize) -> ElectricPotential {
         let max = 4.0 * ElectricPotential::new::<volt>(3.3);
         let duty = self.get_pwm(channel, PwmPin::MaxV);
-        (duty * max, MAX_TEC_V)
+        duty * max
     }
 
     pub fn get_max_i_pos(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) {
+        let max = ElectricCurrent::new::<ampere>(3.0);
         let duty = self.get_pwm(channel, PwmPin::MaxIPos);
-        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
+        (duty * max, max)
     }
 
     pub fn get_max_i_neg(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) {
+        let max = ElectricCurrent::new::<ampere>(3.0);
         let duty = self.get_pwm(channel, PwmPin::MaxINeg);
-        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
+        (duty * max, max)
     }
 
     // Get current passing through TEC
     pub fn get_tec_i(&mut self, channel: usize) -> ElectricCurrent {
-        let tec_i = (self.adc_read(channel, PinsAdcReadTarget::ITec, 16) - self.adc_read(channel, PinsAdcReadTarget::VREF, 16)) / ElectricalResistance::new::<ohm>(0.4);
-        if self.channel_state(channel).polarity_swapped {
+        let tec_i = (self.read_itec(channel) - self.read_vref(channel)) / ElectricalResistance::new::<ohm>(0.4);
+        if self.channel_state(channel).swap_tec_polarity {
             -tec_i
         } else {
             tec_i
@@ -410,7 +407,7 @@ impl Channels {
 
     // Get voltage across TEC
     pub fn get_tec_v(&mut self, channel: usize) -> ElectricPotential {
-        (self.adc_read(channel, PinsAdcReadTarget::VTec, 16) - ElectricPotential::new::<volt>(1.5)) * 4.0
+        (self.read_tec_u_meas(channel) - ElectricPotential::new::<volt>(1.5)) * 4.0
     }
 
     fn set_pwm(&mut self, channel: usize, pin: PwmPin, duty: f64) -> f64 {
@@ -442,29 +439,29 @@ impl Channels {
 
     pub fn set_max_v(&mut self, channel: usize, max_v: ElectricPotential) -> (ElectricPotential, ElectricPotential) {
         let max = 4.0 * ElectricPotential::new::<volt>(3.3);
-        let duty = (max_v.min(MAX_TEC_V).max(ElectricPotential::zero()) / max).get::<ratio>();
+        let duty = (max_v / max).get::<ratio>();
         let duty = self.set_pwm(channel, PwmPin::MaxV, duty);
         (duty * max, max)
     }
 
     pub fn set_max_i_pos(&mut self, channel: usize, max_i_pos: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) {
         let max = ElectricCurrent::new::<ampere>(3.0);
-        let duty = (max_i_pos.min(MAX_TEC_I).max(ElectricCurrent::zero()) / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
+        let duty = (max_i_pos / max).get::<ratio>();
         let duty = self.set_pwm(channel, PwmPin::MaxIPos, duty);
-        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, max)
+        (duty * max, max)
     }
 
     pub fn set_max_i_neg(&mut self, channel: usize, max_i_neg: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) {
         let max = ElectricCurrent::new::<ampere>(3.0);
-        let duty = (max_i_neg.min(MAX_TEC_I).max(ElectricCurrent::zero()) / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
+        let duty = (max_i_neg / max).get::<ratio>();
         let duty = self.set_pwm(channel, PwmPin::MaxINeg, duty);
-        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, max)
+        (duty * max, max)
     }
 
     fn report(&mut self, channel: usize) -> Report {
         let i_set = self.get_i(channel);
-        let i_tec = self.adc_read(channel, PinsAdcReadTarget::ITec, 16);
-        let tec_i = self.get_tec_i(channel);
+        let i_tec = if self.hwrev.major > 2 {Some(self.read_itec(channel))} else {None};
+        let tec_i = if self.hwrev.major > 2 {Some(self.get_tec_i(channel))} else {None};
         let dac_value = self.get_dac(channel);
         let state = self.channel_state(channel);
         let pid_output = ElectricCurrent::new::<ampere>(state.pid.y1);
@@ -477,10 +474,10 @@ impl Channels {
             temperature: state.get_temperature()
                 .map(|temperature| temperature.get::<degree_celsius>()),
             pid_engaged: state.pid_engaged,
-            current_swapped: state.polarity_swapped,
+            current_swapped: state.swap_tec_polarity,
             i_set,
             dac_value,
-            dac_feedback: self.adc_read(channel, PinsAdcReadTarget::DacVfb, 1),
+            dac_feedback: self.read_dac_feedback(channel),
             i_tec,
             tec_i,
             tec_u_meas: self.get_tec_v(channel),
@@ -517,8 +514,8 @@ impl Channels {
         PwmSummary {
             channel,
             center: CenterPointJson(self.channel_state(channel).center.clone()),
-            i_set: (self.get_i(channel), MAX_TEC_I).into(),
-            max_v: self.get_max_v(channel).into(),
+            i_set: (self.get_i(channel), ElectricCurrent::new::<ampere>(3.0)).into(),
+            max_v: (self.get_max_v(channel), ElectricPotential::new::<volt>(5.0)).into(),
             max_i_pos: self.get_max_i_pos(channel).into(),
             max_i_neg: self.get_max_i_neg(channel).into(),
         }
@@ -560,10 +557,9 @@ impl Channels {
     }
 
     pub fn current_abs_max_tec_i(&mut self) -> ElectricCurrent {
-        (0..CHANNELS)
-            .map(|channel| self.get_tec_i(channel).abs())
-            .max_by(|a, b| a.partial_cmp(b).unwrap_or(core::cmp::Ordering::Equal))
-            .unwrap()
+        max_by(self.get_tec_i(0).abs(),
+               self.get_tec_i(1).abs(),
+               |a, b| a.partial_cmp(b).unwrap_or(core::cmp::Ordering::Equal))
     }
 }
 
@@ -580,8 +576,8 @@ pub struct Report {
     i_set: ElectricCurrent,
     dac_value: ElectricPotential,
     dac_feedback: ElectricPotential,
-    i_tec: ElectricPotential,
-    tec_i: ElectricCurrent,
+    i_tec: Option<ElectricPotential>,
+    tec_i: Option<ElectricCurrent>,
     tec_u_meas: ElectricPotential,
     pid_output: ElectricCurrent,
 }

src/command_handler.rs

@@ -181,15 +181,6 @@ impl Handler {
         Ok(Handler::Handled)
     }
 
-    fn swap_polarity (socket: &mut TcpSocket, channels: &mut Channels, channel: usize, swapped: bool) -> Result<Handler, Error> {
-        channels.channel_state(channel).polarity_swapped = swapped;
-        let channel_state = channels.channel_state(channel);
-        let i_set = channel_state.i_set;
-        channels.set_i(channel, i_set);
-        send_line(socket, b"{}");
-        Ok(Handler::Handled)
-    }
-
     fn set_pwm (socket: &mut TcpSocket, channels: &mut Channels, channel: usize, pin: PwmPin, value: f64) -> Result<Handler, Error> {
         match pin {
             PwmPin::ISet => {
@@ -204,21 +195,13 @@ impl Handler {
             }
             PwmPin::MaxIPos => {
                 let current = ElectricCurrent::new::<ampere>(value);
-                if channels.channel_state(channel).polarity_swapped {
-                    channels.set_max_i_neg(channel, current);
-                } else {
                 channels.set_max_i_pos(channel, current);
             }
-            }
             PwmPin::MaxINeg => {
                 let current = ElectricCurrent::new::<ampere>(value);
-                if channels.channel_state(channel).polarity_swapped {
-                    channels.set_max_i_pos(channel, current);
-                } else {
                 channels.set_max_i_neg(channel, current);
             }
         }
-        }
         send_line(socket, b"{}");
         Ok(Handler::Handled)
     }
@@ -362,7 +345,7 @@ impl Handler {
 
     fn set_fan(socket: &mut TcpSocket, fan_pwm: u32, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
         if !fan_ctrl.fan_available() {
-            send_line(socket, b"{ \"warning\": \"this thermostat doesn't have a fan!\" }");
+            send_line(socket, b"{ \"warning\": \"this thermostat doesn't have fan!\" }");
             return Ok(Handler::Handled);
         }
         fan_ctrl.set_auto_mode(false);
@@ -391,7 +374,7 @@ impl Handler {
 
     fn fan_auto(socket: &mut TcpSocket, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
         if !fan_ctrl.fan_available() {
-            send_line(socket, b"{ \"warning\": \"this thermostat doesn't have a fan!\" }");
+            send_line(socket, b"{ \"warning\": \"this thermostat doesn't have fan!\" }");
             return Ok(Handler::Handled);
         }
         fan_ctrl.set_auto_mode(true);
@@ -429,6 +412,16 @@ impl Handler {
         }
     }
 
+    fn swap_tec_polarity (socket: &mut TcpSocket, channels: &mut Channels, channel: Option<usize>) -> Result<Handler, Error> {
+        for c in 0..CHANNELS {
+            if channel.is_none() || channel == Some(c) {
+                channels.channel_state(c).swap_tec_polarity = !channels.channel_state(c).swap_tec_polarity;
+            }
+        }
+        send_line(socket, b"{}");
+        Ok(Handler::Handled)
+    }
+
     pub fn handle_command(command: Command, socket: &mut TcpSocket, channels: &mut Channels, session: &Session, store: &mut FlashStore, ipv4_config: &mut Ipv4Config, fan_ctrl: &mut FanCtrl, hwrev: HWRev) -> Result<Self, Error> {
         match command {
             Command::Quit => Ok(Handler::CloseSocket),
@@ -441,7 +434,6 @@ impl Handler {
             Command::Show(ShowCommand::PostFilter) => Handler::show_post_filter(socket, channels),
             Command::Show(ShowCommand::Ipv4) => Handler::show_ipv4(socket, ipv4_config),
             Command::PwmPid { channel } => Handler::engage_pid(socket, channels, channel),
-            Command::PwmPolaritySwapped { channel, swapped } => Handler::swap_polarity(socket, channels, channel, swapped),
             Command::Pwm { channel, pin, value } => Handler::set_pwm(socket, channels, channel, pin, value),
             Command::CenterPoint { channel, center } => Handler::set_center_point(socket, channels, channel, center),
             Command::Pid { channel, parameter, value } => Handler::set_pid(socket, channels, channel, parameter, value),
@@ -459,6 +451,7 @@ impl Handler {
             Command::FanCurve { k_a, k_b, k_c } => Handler::fan_curve(socket, fan_ctrl, k_a, k_b, k_c),
             Command::FanCurveDefaults => Handler::fan_defaults(socket, fan_ctrl),
             Command::ShowHWRev => Handler::show_hwrev(socket, hwrev),
+            Command::SwapTECPolarity { channel } => Handler::swap_tec_polarity(socket, channels, channel),
         }
     }
 }

src/command_parser.rs

@@ -159,10 +159,6 @@ pub enum Command {
     PwmPid {
         channel: usize,
     },
-    PwmPolaritySwapped {
-        channel: usize,
-        swapped: bool,
-    },
     CenterPoint {
         channel: usize,
         center: CenterPoint,
@@ -195,6 +191,9 @@ pub enum Command {
     },
     FanCurveDefaults,
     ShowHWRev,
+    SwapTECPolarity {
+        channel: Option<usize>,
+    },
 }
 
 fn end(input: &[u8]) -> IResult<&[u8], ()> {
@@ -243,12 +242,6 @@ fn off_on(input: &[u8]) -> IResult<&[u8], bool> {
     ))(input)
 }
 
-fn boolean(input: &[u8]) -> IResult<&[u8], bool> {
-    alt((value(false, tag("false")),
-         value(true, tag("true"))
-    ))(input)
-}
-
 fn channel(input: &[u8]) -> IResult<&[u8], usize> {
     map(one_of("01"), |c| (c as usize) - ('0' as usize))(input)
 }
@@ -331,16 +324,6 @@ fn pwm_pid(input: &[u8]) -> IResult<&[u8], ()> {
     value((), tag("pid"))(input)
 }
 
-fn pwm_polarity_swapped(input: &[u8]) -> IResult<&[u8], bool> {
-    preceded(
-        tag("polarity_swapped"),
-        preceded(
-            whitespace,
-            boolean,
-        )
-    )(input)
-}
-
 fn pwm(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
     let (input, _) = tag("pwm")(input)?;
     alt((
@@ -353,10 +336,6 @@ fn pwm(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
                     let (input, ()) = pwm_pid(input)?;
                     Ok((input, Ok(Command::PwmPid { channel })))
                 },
-                |input| {
-                    let (input, swapped) = pwm_polarity_swapped(input)?;
-                    Ok((input, Ok(Command::PwmPolaritySwapped { channel, swapped })))
-                },
                 |input| {
                     let (input, config) = pwm_setup(input)?;
                     match config {
@@ -608,6 +587,22 @@ fn fan_curve(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
     ))(input)
 }
 
+fn swap(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
+    let (input, _) = tag("swap")(input)?;
+    let (input, channel) = alt((
+        |input| {
+            let (input, _) = whitespace(input)?;
+            let (input, channel) = channel(input)?;
+            let (input, _) = end(input)?;
+            Ok((input, Some(channel)))
+        },
+        value(None, end)
+    ))(input)?;
+
+    let result = Ok(Command::SwapTECPolarity { channel });
+    Ok((input, result))
+}
+
 fn command(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
     alt((value(Ok(Command::Quit), tag("quit")),
          load,
@@ -624,6 +619,7 @@ fn command(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
          fan,
          fan_curve,
          value(Ok(Command::ShowHWRev), tag("hwrev")),
+         swap,
     ))(input)
 }
 

src/config.rs

@@ -1,4 +1,3 @@
-use num_traits::Zero;
 use serde::{Serialize, Deserialize};
 use uom::si::{
     electric_potential::volt,
@@ -19,11 +18,11 @@ pub struct ChannelConfig {
     pid: pid::Parameters,
     pid_target: f32,
     pid_engaged: bool,
-    i_set: ElectricCurrent,
     sh: steinhart_hart::Parameters,
     pwm: PwmLimits,
     /// uses variant `PostFilter::Invalid` instead of `None` to save space
     adc_postfilter: PostFilter,
+    swap_tec_polarity: bool,
 }
 
 impl ChannelConfig {
@@ -35,20 +34,15 @@ impl ChannelConfig {
             .unwrap_or(PostFilter::Invalid);
 
         let state = channels.channel_state(channel);
-        let i_set = if state.pid_engaged { 
-            ElectricCurrent::zero() 
-        } else { 
-            state.i_set 
-        };
         ChannelConfig {
             center: state.center.clone(),
             pid: state.pid.parameters.clone(),
             pid_target: state.pid.target as f32,
             pid_engaged: state.pid_engaged,
-            i_set: i_set,
             sh: state.sh.clone(),
             pwm,
             adc_postfilter,
+            swap_tec_polarity: state.swap_tec_polarity,
         }
     }
 
@@ -59,6 +53,7 @@ impl ChannelConfig {
         state.pid.target = self.pid_target.into();
         state.pid_engaged = self.pid_engaged;
         state.sh = self.sh.clone();
+        state.swap_tec_polarity = self.swap_tec_polarity;
 
         self.pwm.apply(channels, channel);
 
@@ -67,7 +62,6 @@ impl ChannelConfig {
             adc_postfilter => Some(adc_postfilter),
         };
         let _ = channels.adc.set_postfilter(channel as u8, adc_postfilter);
-        let _ = channels.set_i(channel, self.i_set);
     }
 }
 
@@ -80,7 +74,7 @@ struct PwmLimits {
 
 impl PwmLimits {
     pub fn new(channels: &mut Channels, channel: usize) -> Self {
-        let (max_v, _) = channels.get_max_v(channel);
+        let max_v = channels.get_max_v(channel);
         let (max_i_pos, _) = channels.get_max_i_pos(channel);
         let (max_i_neg, _) = channels.get_max_i_neg(channel);
         PwmLimits {

src/fan_ctrl.rs

@@ -54,7 +54,7 @@ impl FanCtrl {
     pub fn cycle(&mut self, abs_max_tec_i: ElectricCurrent) {
         self.abs_max_tec_i = abs_max_tec_i.get::<ampere>() as f32;
         if self.fan_auto && self.hw_settings.fan_available {
-            let scaled_current = self.abs_max_tec_i / MAX_TEC_I.get::<ampere>() as f32;
+            let scaled_current = self.abs_max_tec_i / MAX_TEC_I as f32;
             // do not limit upper bound, as it will be limited in the set_pwm()
             let pwm = (MAX_USER_FAN_PWM * (scaled_current * (scaled_current * self.k_a + self.k_b) + self.k_c)) as u32;
             self.set_pwm(pwm);

src/main.rs

@@ -138,7 +138,7 @@ fn main() -> ! {
 
     let mut store = flash_store::store(dp.FLASH);
 
-    let mut channels = Channels::new(pins);
+    let mut channels = Channels::new(pins, &hwrev);
     for c in 0..CHANNELS {
         match store.read_value::<ChannelConfig>(CHANNEL_CONFIG_KEY[c]) {
             Ok(Some(config)) =>

src/pid.rs

@@ -54,13 +54,15 @@ impl Controller {
     //       + x0 * (kp + ki + kd)
     //       - x1 * (kp + 2kd)
     //       + x2 * kd
+    //       + kp * (u0 - u1)
     // y0  = clip(y0', ymin, ymax)
     pub fn update(&mut self, input: f64) -> f64 {
         
         let mut output: f64 = self.y1 - self.target * f64::from(self.parameters.ki)
                             + input * f64::from(self.parameters.kp + self.parameters.ki + self.parameters.kd)
                             - self.x1 * f64::from(self.parameters.kp + 2.0 * self.parameters.kd)
-                            + self.x2 * f64::from(self.parameters.kd);
+                            + self.x2 * f64::from(self.parameters.kd)
+                            + f64::from(self.parameters.kp) * (self.target - self.u1);
         if output < self.parameters.output_min.into() {
             output = self.parameters.output_min.into();
         }

src/pins.rs

@@ -61,7 +61,7 @@ pub trait ChannelPins {
     type DacSync: OutputPin;
     type Shdn: OutputPin;
     type VRefPin;
-    type ITecPin;
+    type ItecPin;
     type DacFeedbackPin;
     type TecUMeasPin;
 }
@@ -76,7 +76,7 @@ impl ChannelPins for Channel0 {
     type DacSync = PE4<Output<PushPull>>;
     type Shdn = PE10<Output<PushPull>>;
     type VRefPin = Channel0VRef;
-    type ITecPin = PA6<Analog>;
+    type ItecPin = PA6<Analog>;
     type DacFeedbackPin = PA4<Analog>;
     type TecUMeasPin = PC2<Analog>;
 }
@@ -91,7 +91,7 @@ impl ChannelPins for Channel1 {
     type DacSync = PF6<Output<PushPull>>;
     type Shdn = PE15<Output<PushPull>>;
     type VRefPin = Channel1VRef;
-    type ITecPin = PB0<Analog>;
+    type ItecPin = PB0<Analog>;
     type DacFeedbackPin = PA5<Analog>;
     type TecUMeasPin = PC3<Analog>;
 }
@@ -108,7 +108,7 @@ pub struct ChannelPinSet<C: ChannelPins> {
     pub dac_sync: C::DacSync,
     pub shdn: C::Shdn,
     pub vref_pin: C::VRefPin,
-    pub itec_pin: C::ITecPin,
+    pub itec_pin: C::ItecPin,
     pub dac_feedback_pin: C::DacFeedbackPin,
     pub tec_u_meas_pin: C::TecUMeasPin,
 }