Limit i_set within range of MAX1968 chip

The REF pin of the MAX1968 on hardware revisions v2.x is missing a
buffer, loading the pin on every CPU ADC read. Avoid reading from it and
leave the pin floating on affected hardware revisions, and return the
nominal 1.5V instead.

Cargo.lock

@@ -327,10 +327,10 @@ dependencies = [
 ]
 
 [[package]]
-name = "panic-abort"
+name = "panic-halt"
-version = "0.3.2"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e20e6499bbbc412f280b04a42346b356c6fa0753d5fd22b7bd752ff34c778ee"
+checksum = "de96540e0ebde571dc55c73d60ef407c653844e6f9a1e2fdbd40c07b9252d812"
 
 [[package]]
 name = "panic-semihosting"
@@ -563,7 +563,7 @@ dependencies = [
  "nb 1.0.0",
  "nom",
  "num-traits",
- "panic-abort",
+ "panic-halt",
  "panic-semihosting",
  "serde",
  "serde-json-core",

Cargo.toml

@@ -7,14 +7,14 @@ authors = ["Astro <astro@spaceboyz.net>"]
 version = "0.0.0"
 keywords = ["thermostat", "laser", "physics"]
 repository = "https://git.m-labs.hk/M-Labs/thermostat"
-edition = "2018"
+edition = "2021"
 
 [package.metadata.docs.rs]
 features = []
 default-target = "thumbv7em-none-eabihf"
 
 [dependencies]
-panic-abort = "0.3"
+panic-halt = "0.2"
 panic-semihosting = { version = "0.5", optional = true }
 log = "0.4"
 bare-metal = "1"

README.md

@@ -29,7 +29,7 @@ Alternatively, you can install the Rust toolchain without Nix using rustup; see
 
 Connect SWDIO/SWCLK/RST/GND to a programmer such as ST-Link v2.1. Run OpenOCD:
 ```shell
-openocd -f interface/stlink-v2-1.cfg -f target/stm32f4x.cfg
+openocd -f interface/stlink.cfg -f target/stm32f4x.cfg
 ```
 
 You may need to power up the programmer before powering the device.
@@ -64,7 +64,7 @@ On a Windows machine install [st.com](https://st.com) DfuSe USB device firmware
 
 ### OpenOCD
 ```shell
-openocd -f interface/stlink-v2-1.cfg -f target/stm32f4x.cfg -c "program target/thumbv7em-none-eabihf/release/thermostat verify reset;exit"
+openocd -f interface/stlink.cfg -f target/stm32f4x.cfg -c "program target/thumbv7em-none-eabihf/release/thermostat verify reset;exit"
 ```
 
 ## Network
@@ -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                                                               |
@@ -124,6 +124,12 @@ formatted as line-delimited JSON.
 | `reset`                          | Reset the device                                                              |
 | `dfu`                            | Reset device and enters USB device firmware update (DFU) mode                 |
 | `ipv4 <X.X.X.X/L> [Y.Y.Y.Y]`     | Configure IPv4 address, netmask length, and optional default gateway          |
+| `fan`                            | Show current fan settings and sensors' measurements                           |
+| `fan <value>`                    | Set fan power with values from 1 to 100                                       |
+| `fan auto`                       | Enable automatic fan speed control                                            |
+| `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                            |
 
 
 ## USB
@@ -178,7 +184,7 @@ postfilter rate can be tuned with the `postfilter` command.
 - Connect TEC module device 1 to TEC1- and TEC1+.
 - The GND pin is for shielding not for sinking TEC module currents.
 
-When using a TEC module with the Thermostat, the Thermostat expects the thermal load (where the thermistor is located) to heat up with a positive software current set point, and cool down with a negative current set point.
+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.
 
 Testing heat flow direction with a low set current is recommended before installation of the TEC module.
 
@@ -252,13 +258,12 @@ with the following keys.
 | Key            | Unit            | Description                                          |
 | ---            | :---:           | ---                                                  |
 | `channel`      | Integer         | Channel `0`, or `1`                                  |
-| `time`         | Milliseconds    | Temperature measurement time                         |
+| `time`         | Seconds         | Temperature measurement time                         |
 | `adc`          | Volts           | AD7172 input                                         |
 | `sens`         | Ohms            | Thermistor resistance derived from `adc`             |
 | `temperature`  | Degrees Celsius | Steinhart-Hart conversion result derived from `sens` |
 | `pid_engaged`  | Boolean         | `true` if in closed-loop mode                        |
 | `i_set`        | Amperes         | TEC output current                                   |
-| `vref`         | Volts           | MAX1968 VREF (1.5 V)                                 |
 | `dac_value`    | Volts           | AD5680 output derived from `i_set`                   |
 | `dac_feedback` | Volts           | ADC measurement of the AD5680 output                 |
 | `i_tec`        | Volts           | MAX1968 TEC current monitor                          |
@@ -266,6 +271,19 @@ 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 disabled and null due to faulty hardware that introduces a lot of noise in the signal.
+
 ## PID Tuning
 
 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).
+
+## Fan control
+
+Fan control commands are available for thermostat revisions with an integrated fan system:
+1. `fan` - show fan stats: `fan_pwm`, `abs_max_tec_i`, `auto_mode`, `k_a`, `k_b`, `k_c`.
+2. `fan auto` - enable auto speed controller mode, where fan speed is controlled by the fan curve `fcurve`.
+3. `fan <value>` - set the fan power with the value from `1` to `100` and disable auto mode. There is no way to completely disable the fan.
+Please note that power doesn't correlate with the actual speed linearly.
+4. `fcurve <a> <b> <c>` - set coefficients of the controlling curve `a*x^2 + b*x + c`, where `x` is `abs_max_tec_i/MAX_TEC_I`, a normalized value in range [0,1],
+i.e. the (linear) proportion of current output capacity used, on the channel with the largest current flow. The controlling curve is also clamped to [0,1].
+5. `fcurve default` - restore fan curve coefficients to defaults: `a = 1.0, b = 0.0, c = 0.0`.

flake.lock

@@ -3,11 +3,11 @@
     "mozilla-overlay": {
       "flake": false,
       "locked": {
-        "lastModified": 1638887313,
+        "lastModified": 1690536331,
-        "narHash": "sha256-FMYV6rVtvSIfthgC1sK1xugh3y7muoQcvduMdriz4ag=",
+        "narHash": "sha256-aRIf2FB2GTdfF7gl13WyETmiV/J7EhBGkSWXfZvlxcA=",
         "owner": "mozilla",
         "repo": "nixpkgs-mozilla",
-        "rev": "7c1e8b1dd6ed0043fb4ee0b12b815256b0b9de6f",
+        "rev": "db89c8707edcffefcd8e738459d511543a339ff5",
         "type": "github"
       },
       "original": {
@@ -18,16 +18,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1641870998,
+        "lastModified": 1691421349,
-        "narHash": "sha256-6HkxR2WZsm37VoQS7jgp6Omd71iw6t1kP8bDbaqCDuI=",
+        "narHash": "sha256-RRJyX0CUrs4uW4gMhd/X4rcDG8PTgaaCQM5rXEJOx6g=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "386234e2a61e1e8acf94dfa3a3d3ca19a6776efb",
+        "rev": "011567f35433879aae5024fc6ec53f2a0568a6c4",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-21.11",
+        "ref": "nixos-23.05",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,15 +1,15 @@
 {
   description = "Firmware for the Sinara 8451 Thermostat";
 
-  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-21.11;
+  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-23.05;
   inputs.mozilla-overlay = { url = github:mozilla/nixpkgs-mozilla; flake = false; };
 
   outputs = { self, nixpkgs, mozilla-overlay }:
     let
       pkgs = import nixpkgs { system = "x86_64-linux"; overlays = [ (import mozilla-overlay) ]; };
       rustManifest = pkgs.fetchurl {
-        url = "https://static.rust-lang.org/dist/2021-10-26/channel-rust-nightly.toml";
+        url = "https://static.rust-lang.org/dist/2022-12-15/channel-rust-stable.toml";
-        sha256 = "sha256-1hLbypXA+nuH7o3AHCokzSBZAvQxvef4x9+XxO3aBao=";
+        hash = "sha256-S7epLlflwt0d1GZP44u5Xosgf6dRrmr8xxC+Ml2Pq7c=";
       };
 
       targets = [
@@ -22,12 +22,12 @@
           inherit targets;
           extensions = ["rust-src"];
         };
-      rust = rustChannelOfTargets "nightly" null targets;
+      rust = rustChannelOfTargets "stable" null targets;
       rustPlatform = pkgs.recurseIntoAttrs (pkgs.makeRustPlatform {
         rustc = rust;
         cargo = rust;
       });
-      thermostat = rustPlatform.buildRustPackage rec {
+      thermostat = rustPlatform.buildRustPackage {
         name = "thermostat";
         version = "0.0.0";
 
@@ -67,9 +67,7 @@
       devShell.x86_64-linux = pkgs.mkShell {
         name = "thermostat-dev-shell";
         buildInputs = with pkgs; [
-          rustPlatform.rust.rustc
+          rust openocd dfu-util
-          rustPlatform.rust.cargo
-          openocd dfu-util
           ] ++ (with python3Packages; [
             numpy matplotlib
           ]);

pytec/pytec/client.py

@@ -1,5 +1,6 @@
 import socket
 import json
+import logging
 
 class CommandError(Exception):
     pass
@@ -8,6 +9,14 @@ class Client:
     def __init__(self, host="192.168.1.26", port=23, timeout=None):
         self._socket = socket.create_connection((host, port), timeout)
         self._lines = [""]
+        self._check_zero_limits()
+
+    def _check_zero_limits(self):
+        pwm_report = self.get_pwm()
+        for pwm_channel in pwm_report:
+            for limit in ["max_i_neg", "max_i_pos", "max_v"]:
+                if pwm_channel[limit]["value"] == 0.0:
+                    logging.warning("`{}` limit is set to zero on channel {}".format(limit, pwm_channel["channel"]))
 
     def _read_line(self):
         # read more lines

src/channel_state.rs

@@ -2,11 +2,13 @@ use smoltcp::time::{Duration, Instant};
 use uom::si::{
     f64::{
         ElectricPotential,
+        ElectricCurrent,
         ElectricalResistance,
         ThermodynamicTemperature,
         Time,
     },
     electric_potential::volt,
+    electric_current::ampere,
     electrical_resistance::ohm,
     thermodynamic_temperature::degree_celsius,
     time::millisecond,
@@ -26,11 +28,10 @@ pub struct ChannelState {
     pub adc_calibration: ad7172::ChannelCalibration,
     pub adc_time: Instant,
     pub adc_interval: Duration,
-    /// VREF for the TEC (1.5V)
-    pub vref: ElectricPotential,
     /// i_set 0A center point
     pub center: CenterPoint,
     pub dac_value: ElectricPotential,
+    pub i_set: ElectricCurrent,
     pub pid_engaged: bool,
     pub pid: pid::Controller,
     pub sh: sh::Parameters,
@@ -44,10 +45,9 @@ impl ChannelState {
             adc_time: Instant::from_secs(0),
             // default: 10 Hz
             adc_interval: Duration::from_millis(100),
-            // updated later with Channels.read_vref()
-            vref: ElectricPotential::new::<volt>(1.5),
             center: CenterPoint::Vref,
             dac_value: ElectricPotential::new::<volt>(0.0),
+            i_set: ElectricCurrent::new::<ampere>(0.0),
             pid_engaged: false,
             pid: pid::Controller::new(pid::Parameters::default()),
             sh: sh::Parameters::default(),

src/channels.rs

@@ -1,4 +1,5 @@
-use heapless::{consts::{U2, U1024}, Vec};
+use core::cmp::max_by;
+use heapless::{consts::U2, Vec};
 use serde::{Serialize, Serializer};
 use smoltcp::time::Instant;
 use stm32f4xx_hal::hal;
@@ -16,27 +17,34 @@ use crate::{
     channel::{Channel, Channel0, Channel1},
     channel_state::ChannelState,
     command_parser::{CenterPoint, PwmPin},
-    pins,
+    command_handler::JsonBuffer,
+    pins::{self, Channel0VRef, Channel1VRef},
     steinhart_hart,
+    hw_rev,
 };
 
 pub const CHANNELS: usize = 2;
 pub const R_SENSE: f64 = 0.05;
+
+// 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: 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 {
+impl<'a> Channels<'a> {
-    pub fn new(pins: pins::Pins) -> Self {
+    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();
@@ -54,9 +62,8 @@ 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.channel_state(channel).vref = channels.read_vref(channel);
             channels.calibrate_dac_value(channel);
             channels.set_i(channel, ElectricCurrent::new::<ampere>(0.0));
         }
@@ -96,11 +103,8 @@ impl Channels {
     /// calculate the TEC i_set centerpoint
     pub fn get_center(&mut self, channel: usize) -> ElectricPotential {
         match self.channel_state(channel).center {
-            CenterPoint::Vref => {
+            CenterPoint::Vref =>
-                let vref = self.read_vref(channel);
+                self.read_vref(channel),
-                self.channel_state(channel).vref = vref;
-                vref
-            },
             CenterPoint::Override(center_point) =>
                 ElectricPotential::new::<volt>(center_point.into()),
         }
@@ -113,11 +117,8 @@ impl Channels {
     }
 
     pub fn get_i(&mut self, channel: usize) -> ElectricCurrent {
-        let center_point = self.get_center(channel);
+        let i_set = self.channel_state(channel).i_set;
-        let r_sense = ElectricalResistance::new::<ohm>(R_SENSE);
+        i_set
-        let voltage = self.get_dac(channel);
-        let i_tec = (voltage - center_point) / (10.0 * r_sense);
-        i_tec
     }
 
     /// i_set DAC
@@ -132,7 +133,12 @@ impl Channels {
         voltage
     }
 
-    pub fn set_i(&mut self, channel: usize, i_tec: ElectricCurrent) -> ElectricCurrent {
+    pub fn set_i(&mut self, channel: usize, i_set: ElectricCurrent) -> ElectricCurrent {
+        // Silently clamp i_set
+        let i_ceiling = ElectricCurrent::new::<ampere>(MAX_TEC_I);
+        let i_floor = ElectricCurrent::new::<ampere>(-MAX_TEC_I);
+        let 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,
@@ -140,10 +146,11 @@ impl Channels {
         };
         let center_point = vref_meas;
         let r_sense = ElectricalResistance::new::<ohm>(R_SENSE);
-        let voltage = i_tec * 10.0 * r_sense + center_point;
+        let voltage = i_set * 10.0 * r_sense + center_point;
         let voltage = self.set_dac(channel, voltage);
-        let i_tec = (voltage - center_point) / (10.0 * r_sense);
+        let i_set = (voltage - center_point) / (10.0 * r_sense);
-        i_tec
+        self.channel_state(channel).i_set = i_set;
+        i_set
     }
 
     pub fn read_dac_feedback(&mut self, channel: usize) -> ElectricPotential {
@@ -205,20 +212,30 @@ impl Channels {
     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(
-                    &self.channel0.vref_pin,
+                            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(
-                    &self.channel1.vref_pin,
+                            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!(),
         }
@@ -430,10 +447,9 @@ impl Channels {
     }
 
     fn report(&mut self, channel: usize) -> Report {
-        let vref = self.channel_state(channel).vref;
         let i_set = self.get_i(channel);
-        let i_tec = self.read_itec(channel);
+        let i_tec = if self.hwrev.major > 2 {Some(self.read_itec(channel))} else {None};
-        let tec_i = self.get_tec_i(channel);
+        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);
@@ -447,7 +463,6 @@ impl Channels {
                 .map(|temperature| temperature.get::<degree_celsius>()),
             pid_engaged: state.pid_engaged,
             i_set,
-            vref,
             dac_value,
             dac_feedback: self.read_dac_feedback(channel),
             i_tec,
@@ -473,6 +488,15 @@ impl Channels {
         serde_json_core::to_vec(&summaries)
     }
 
+    pub fn pid_engaged(&mut self) -> bool {
+        for channel in 0..CHANNELS {
+            if self.channel_state(channel).pid_engaged {
+                return true;
+            }
+        }
+        false
+    }
+
     fn pwm_summary(&mut self, channel: usize) -> PwmSummary {
         PwmSummary {
             channel,
@@ -518,9 +542,13 @@ impl Channels {
         }
         serde_json_core::to_vec(&summaries)
     }
-}
 
-type JsonBuffer = Vec<u8, U1024>;
+    pub fn current_abs_max_tec_i(&mut self) -> ElectricCurrent {
+        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))
+    }
+}
 
 #[derive(Serialize)]
 pub struct Report {
@@ -532,11 +560,10 @@ pub struct Report {
     temperature: Option<f64>,
     pid_engaged: bool,
     i_set: ElectricCurrent,
-    vref: ElectricPotential,
     dac_value: ElectricPotential,
     dac_feedback: ElectricPotential,
-    i_tec: ElectricPotential,
+    i_tec: Option<ElectricPotential>,
-    tec_i: ElectricCurrent,
+    tec_i: Option<ElectricCurrent>,
     tec_u_meas: ElectricPotential,
     pid_output: ElectricCurrent,
 }

src/command_handler.rs

@@ -1,6 +1,7 @@
 use smoltcp::socket::TcpSocket;
 use log::{error, warn};
 use core::fmt::Write;
+use heapless::{consts::U1024, Vec};
 use super::{
     net,
     command_parser::{
@@ -12,7 +13,6 @@ use super::{
         PwmPin, 
         ShParameter
     },
-    leds::Leds,
     ad7172,
     CHANNEL_CONFIG_KEY,
     channels::{
@@ -22,7 +22,9 @@ use super::{
     config::ChannelConfig,
     dfu,
     flash_store::FlashStore,
-    session::Session
+    session::Session,
+    FanCtrl,
+    hw_rev::HWRev,
 };
 
 use uom::{
@@ -55,6 +57,8 @@ pub enum Error {
     FlashError
 }
 
+pub type JsonBuffer = Vec<u8, U1024>;
+
 fn send_line(socket: &mut TcpSocket, data: &[u8]) -> bool {
     let send_free = socket.send_capacity() - socket.send_queue();
     if data.len() > send_free + 1 {
@@ -171,18 +175,16 @@ impl Handler {
         Ok(Handler::Handled)
     }
 
-    fn engage_pid (socket: &mut TcpSocket, channels: &mut Channels, leds: &mut Leds, channel: usize) -> Result<Handler, Error> {
+    fn engage_pid (socket: &mut TcpSocket, channels: &mut Channels, channel: usize) -> Result<Handler, Error> {
         channels.channel_state(channel).pid_engaged = true;
-        leds.g3.on();
         send_line(socket, b"{}");
         Ok(Handler::Handled)
     }
 
-    fn set_pwm (socket: &mut TcpSocket, channels: &mut Channels, leds: &mut Leds, channel: usize, pin: PwmPin, value: f64) -> Result<Handler, Error> {
+    fn set_pwm (socket: &mut TcpSocket, channels: &mut Channels, channel: usize, pin: PwmPin, value: f64) -> Result<Handler, Error> {
         match pin {
             PwmPin::ISet => {
                 channels.channel_state(channel).pid_engaged = false;
-                leds.g3.off();
                 let current = ElectricCurrent::new::<ampere>(value);
                 channels.set_i(channel, current);
                 channels.power_up(channel);
@@ -205,11 +207,11 @@ impl Handler {
     }
 
     fn set_center_point(socket: &mut TcpSocket, channels: &mut Channels, channel: usize, center: CenterPoint) -> Result<Handler, Error> {
-        let i_tec = channels.get_i(channel);
+        let i_set = channels.get_i(channel);
         let state = channels.channel_state(channel);
         state.center = center;
         if !state.pid_engaged {
-            channels.set_i(channel, i_tec);
+            channels.set_i(channel, i_set);
         }
         send_line(socket, b"{}");
         Ok(Handler::Handled)
@@ -341,7 +343,76 @@ impl Handler {
         Ok(Handler::Reset)
     }
 
-    pub fn handle_command (command: Command, socket: &mut TcpSocket, channels: &mut Channels, session: &Session, leds: &mut Leds, store: &mut FlashStore, ipv4_config: &mut Ipv4Config) -> Result<Self, Error> {
+    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 fan!\" }");
+            return Ok(Handler::Handled);
+        }
+        fan_ctrl.set_auto_mode(false);
+        fan_ctrl.set_pwm(fan_pwm);
+        if fan_ctrl.fan_pwm_recommended() {
+            send_line(socket, b"{}");
+        } else {
+            send_line(socket, b"{ \"warning\": \"this fan doesn't have full PWM support. Use it at your own risk!\" }");
+        }
+        Ok(Handler::Handled)
+    }
+
+    fn show_fan(socket: &mut TcpSocket, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
+        match fan_ctrl.summary() {
+            Ok(buf) => {
+                send_line(socket, &buf);
+                Ok(Handler::Handled)
+            }
+            Err(e) => {
+                error!("unable to serialize fan summary: {:?}", e);
+                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
+                Err(Error::ReportError)
+            }
+        }
+    }
+
+    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 fan!\" }");
+            return Ok(Handler::Handled);
+        }
+        fan_ctrl.set_auto_mode(true);
+        if fan_ctrl.fan_pwm_recommended() {
+            send_line(socket, b"{}");
+        } else {
+            send_line(socket, b"{ \"warning\": \"this fan doesn't have full PWM support. Use it at your own risk!\" }");
+        }
+        Ok(Handler::Handled)
+    }
+
+    fn fan_curve(socket: &mut TcpSocket, fan_ctrl: &mut FanCtrl, k_a: f32, k_b: f32, k_c: f32) -> Result<Handler, Error> {
+        fan_ctrl.set_curve(k_a, k_b, k_c);
+        send_line(socket, b"{}");
+        Ok(Handler::Handled)
+    }
+
+    fn fan_defaults(socket: &mut TcpSocket, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
+        fan_ctrl.restore_defaults();
+        send_line(socket, b"{}");
+        Ok(Handler::Handled)
+    }
+
+    fn show_hwrev(socket: &mut TcpSocket, hwrev: HWRev) -> Result<Handler, Error> {
+        match hwrev.summary() {
+            Ok(buf) => {
+                send_line(socket, &buf);
+                Ok(Handler::Handled)
+            }
+            Err(e) => {
+                error!("unable to serialize HWRev summary: {:?}", e);
+                let _ = writeln!(socket, "{{\"error\":\"{:?}\"}}", e);
+                Err(Error::ReportError)
+            }
+        }
+    }
+
+    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),
             Command::Reporting(_reporting) => Handler::reporting(socket),            
@@ -352,8 +423,8 @@ impl Handler {
             Command::Show(ShowCommand::SteinhartHart) => Handler::show_steinhart_hart(socket, channels),
             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, leds, channel),
+            Command::PwmPid { channel } => Handler::engage_pid(socket, channels, channel),
-            Command::Pwm { channel, pin, value } => Handler::set_pwm(socket, channels, leds, channel, pin, value),
+            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),
             Command::SteinhartHart { channel, parameter, value } => Handler::set_steinhart_hart(socket, channels, channel, parameter, value),
@@ -363,7 +434,13 @@ impl Handler {
             Command::Save { channel } => Handler::save_channel(socket, channels, channel, store),
             Command::Ipv4(config) => Handler::set_ipv4(socket, store, config),
             Command::Reset => Handler::reset(channels),
-            Command::Dfu => Handler::dfu(channels)
+            Command::Dfu => Handler::dfu(channels),
+            Command::FanSet {fan_pwm} => Handler::set_fan(socket, fan_pwm, fan_ctrl),
+            Command::ShowFan => Handler::show_fan(socket, fan_ctrl),
+            Command::FanAuto => Handler::fan_auto(socket, fan_ctrl),
+            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),
         }
     }
 }

src/command_parser.rs

@@ -10,6 +10,7 @@ use nom::{
     sequence::preceded,
     multi::{fold_many0, fold_many1},
     error::ErrorKind,
+    Needed,
 };
 use num_traits::{Num, ParseFloatError};
 use serde::{Serialize, Deserialize};
@@ -178,6 +179,18 @@ pub enum Command {
         rate: Option<f32>,
     },
     Dfu,
+    FanSet {
+        fan_pwm: u32
+    },
+    FanAuto,
+    ShowFan,
+    FanCurve {
+        k_a: f32,
+        k_b: f32,
+        k_c: f32,
+    },
+    FanCurveDefaults,
+    ShowHWRev,
 }
 
 fn end(input: &[u8]) -> IResult<&[u8], ()> {
@@ -520,6 +533,57 @@ fn ipv4(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
     ))(input)
 }
 
+fn fan(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
+    let (input, _) = tag("fan")(input)?;
+    alt((
+        |input| {
+            let (input, _) = whitespace(input)?;
+
+            let (input, result) = alt((
+                |input| {
+                    let (input, _) = tag("auto")(input)?;
+                    Ok((input, Ok(Command::FanAuto)))
+                },
+                |input| {
+                    let (input, value) = unsigned(input)?;
+                    Ok((input, Ok(Command::FanSet { fan_pwm: value.unwrap_or(0)})))
+                },
+            ))(input)?;
+            Ok((input, result))
+        },
+        value(Ok(Command::ShowFan), end)
+    ))(input)
+}
+
+fn fan_curve(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
+    let (input, _) = tag("fcurve")(input)?;
+    alt((
+        |input| {
+            let (input, _) = whitespace(input)?;
+            let (input, result) = alt((
+                |input| {
+                    let (input, _) = tag("default")(input)?;
+                    Ok((input, Ok(Command::FanCurveDefaults)))
+                },
+                |input| {
+                    let (input, k_a) = float(input)?;
+                    let (input, _) = whitespace(input)?;
+                    let (input, k_b) = float(input)?;
+                    let (input, _) = whitespace(input)?;
+                    let (input, k_c) = float(input)?;
+                    if k_a.is_ok() && k_b.is_ok() && k_c.is_ok() {
+                        Ok((input, Ok(Command::FanCurve { k_a: k_a.unwrap() as f32, k_b: k_b.unwrap() as f32, k_c: k_c.unwrap() as f32 })))
+                    } else {
+                        Err(nom::Err::Incomplete(Needed::Size(3)))
+                    }
+                },
+            ))(input)?;
+            Ok((input, result))
+        },
+        value(Err(Error::Incomplete), end)
+    ))(input)
+}
+
 fn command(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
     alt((value(Ok(Command::Quit), tag("quit")),
          load,
@@ -533,6 +597,9 @@ fn command(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
          steinhart_hart,
          postfilter,
          value(Ok(Command::Dfu), tag("dfu")),
+         fan,
+         fan_curve,
+         value(Ok(Command::ShowHWRev), tag("hwrev")),
     ))(input)
 }
 
@@ -754,4 +821,44 @@ mod test {
             center: CenterPoint::Vref,
         }));
     }
+
+    #[test]
+    fn parse_fan_show() {
+        let command = Command::parse(b"fan");
+        assert_eq!(command, Ok(Command::ShowFan));
+    }
+
+    #[test]
+    fn parse_fan_set() {
+        let command = Command::parse(b"fan 42");
+        assert_eq!(command, Ok(Command::FanSet {fan_pwm: 42}));
+    }
+
+    #[test]
+    fn parse_fan_auto() {
+        let command = Command::parse(b"fan auto");
+        assert_eq!(command, Ok(Command::FanAuto));
+    }
+
+    #[test]
+    fn parse_fcurve_set() {
+        let command = Command::parse(b"fcurve 1.2 3.4 5.6");
+        assert_eq!(command, Ok(Command::FanCurve {
+            k_a: 1.2,
+            k_b: 3.4,
+            k_c: 5.6
+        }));
+    }
+
+    #[test]
+    fn parse_fcurve_default() {
+        let command = Command::parse(b"fcurve default");
+        assert_eq!(command, Ok(Command::FanCurveDefaults));
+    }
+
+    #[test]
+    fn parse_hwrev() {
+        let command = Command::parse(b"hwrev");
+        assert_eq!(command, Ok(Command::ShowHWRev));
+    }
 }

src/dfu.rs

@@ -1,3 +1,4 @@
+use core::arch::asm;
 use cortex_m_rt::pre_init;
 use stm32f4xx_hal::stm32::{RCC, SYSCFG};
 

src/fan_ctrl.rs

@@ -0,0 +1,152 @@
+use num_traits::Float;
+use serde::Serialize;
+use stm32f4xx_hal::{
+    pwm::{self, PwmChannels},
+    pac::TIM8,
+};
+use uom::si::{
+    f64::ElectricCurrent,
+    electric_current::ampere,
+};
+use crate::{
+    hw_rev::HWSettings,
+    command_handler::JsonBuffer,
+    channels::MAX_TEC_I,
+};
+
+pub type FanPin = PwmChannels<TIM8, pwm::C4>;
+
+const MAX_USER_FAN_PWM: f32 = 100.0;
+const MIN_USER_FAN_PWM: f32 = 1.0;
+
+
+pub struct FanCtrl {
+    fan: Option<FanPin>,
+    fan_auto: bool,
+    pwm_enabled: bool,
+    k_a: f32,
+    k_b: f32,
+    k_c: f32,
+    abs_max_tec_i: f32,
+    hw_settings: HWSettings,
+}
+
+impl FanCtrl {
+    pub fn new(fan: Option<FanPin>, hw_settings: HWSettings) -> Self {
+        let mut fan_ctrl = FanCtrl {
+            fan,
+            // do not enable auto mode by default,
+            // but allow to turn it at the user's own risk
+            fan_auto: hw_settings.fan_pwm_recommended,
+            pwm_enabled: false,
+            k_a: hw_settings.fan_k_a,
+            k_b: hw_settings.fan_k_b,
+            k_c: hw_settings.fan_k_c,
+            abs_max_tec_i: 0f32,
+            hw_settings,
+        };
+        if fan_ctrl.fan_auto {
+            fan_ctrl.enable_pwm();
+        }
+        fan_ctrl
+    }
+
+    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 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);
+        }
+    }
+
+    pub fn summary(&mut self) -> Result<JsonBuffer, serde_json_core::ser::Error> {
+        if self.hw_settings.fan_available {
+            let summary = FanSummary {
+                fan_pwm: self.get_pwm(),
+                abs_max_tec_i: self.abs_max_tec_i,
+                auto_mode: self.fan_auto,
+                k_a: self.k_a,
+                k_b: self.k_b,
+                k_c: self.k_c,
+            };
+            serde_json_core::to_vec(&summary)
+        } else {
+            let summary: Option<()> = None;
+            serde_json_core::to_vec(&summary)
+        }
+    }
+
+    pub fn set_auto_mode(&mut self, fan_auto: bool) {
+        self.fan_auto = fan_auto;
+    }
+
+    pub fn set_curve(&mut self, k_a: f32, k_b: f32, k_c: f32) {
+        self.k_a = k_a;
+        self.k_b = k_b;
+        self.k_c = k_c;
+    }
+
+    pub fn restore_defaults(&mut self) {
+        self.set_curve(self.hw_settings.fan_k_a,
+                       self.hw_settings.fan_k_b,
+                       self.hw_settings.fan_k_c);
+    }
+
+    pub fn set_pwm(&mut self, fan_pwm: u32) -> f32 {
+        if self.fan.is_none() || (!self.pwm_enabled && !self.enable_pwm())  {
+            return 0f32;
+        }
+        let fan = self.fan.as_mut().unwrap();
+        let fan_pwm = fan_pwm.min(MAX_USER_FAN_PWM as u32).max(MIN_USER_FAN_PWM as u32);
+        let duty = scale_number(fan_pwm as f32, self.hw_settings.min_fan_pwm, self.hw_settings.max_fan_pwm, MIN_USER_FAN_PWM, MAX_USER_FAN_PWM);
+        let max = fan.get_max_duty();
+        let value = ((duty * (max as f32)) as u16).min(max);
+        fan.set_duty(value);
+        value as f32 / (max as f32)
+    }
+
+    pub fn fan_pwm_recommended(&self) -> bool {
+        self.hw_settings.fan_pwm_recommended
+    }
+
+    pub fn fan_available(&self) -> bool {
+        self.hw_settings.fan_available
+    }
+
+    fn get_pwm(&self) -> u32 {
+        if let Some(fan) = &self.fan {
+            let duty = fan.get_duty();
+            let max = fan.get_max_duty();
+            scale_number(duty as f32 / (max as f32), MIN_USER_FAN_PWM, MAX_USER_FAN_PWM, self.hw_settings.min_fan_pwm, self.hw_settings.max_fan_pwm).round() as u32
+        } else { 0 }
+    }
+
+    fn enable_pwm(&mut self) -> bool {
+        if self.fan.is_some() && self.hw_settings.fan_available {
+            let fan = self.fan.as_mut().unwrap();
+            fan.set_duty(0);
+            fan.enable();
+            self.pwm_enabled = true;
+            true
+        } else {
+            false
+        }
+    }
+}
+
+
+fn scale_number(unscaled: f32, to_min: f32, to_max: f32, from_min: f32, from_max: f32) -> f32 {
+    (to_max - to_min) * (unscaled - from_min) / (from_max - from_min) + to_min
+}
+
+#[derive(Serialize)]
+pub struct FanSummary {
+    fan_pwm: u32,
+    abs_max_tec_i: f32,
+    auto_mode: bool,
+    k_a: f32,
+    k_b: f32,
+    k_c: f32,
+}

src/hw_rev.rs

@@ -0,0 +1,82 @@
+use serde::Serialize;
+
+use crate::{
+    pins::HWRevPins,
+    command_handler::JsonBuffer,
+};
+
+#[derive(Serialize, Copy, Clone)]
+pub struct HWRev {
+    pub major: u8,
+    pub minor: u8,
+}
+
+#[derive(Serialize, Clone)]
+pub struct HWSettings {
+    pub fan_k_a: f32,
+    pub fan_k_b: f32,
+    pub fan_k_c: f32,
+    pub min_fan_pwm: f32,
+    pub max_fan_pwm: f32,
+    pub fan_pwm_freq_hz: u32,
+    pub fan_available: bool,
+    pub fan_pwm_recommended: bool,
+}
+
+#[derive(Serialize, Clone)]
+struct HWSummary<'a> {
+    rev: &'a HWRev,
+    settings: &'a HWSettings,
+}
+
+impl HWRev {
+    pub fn detect_hw_rev(hwrev_pins: &HWRevPins) -> Self {
+        let (h0, h1, h2, h3) = (hwrev_pins.hwrev0.is_high(), hwrev_pins.hwrev1.is_high(),
+                                hwrev_pins.hwrev2.is_high(), hwrev_pins.hwrev3.is_high());
+        match (h0, h1, h2, h3) {
+            (true, true, true, false) => HWRev { major: 1, minor: 0 },
+            (true, false, false, false) => HWRev { major: 2, minor: 0 },
+            (false, true, false, false) => HWRev { major: 2, minor: 2 },
+            (_, _, _, _) => HWRev { major: 0, minor: 0 }
+        }
+    }
+
+    pub fn settings(&self) -> HWSettings {
+        match (self.major, self.minor) {
+            (2, 2) => HWSettings {
+                fan_k_a: 1.0,
+                fan_k_b: 0.0,
+                fan_k_c: 0.0,
+                // below this value motor's autostart feature may fail,
+                // according to internal experiments
+                min_fan_pwm: 0.04,
+                max_fan_pwm: 1.0,
+                // According to `SUNON DC Brushless Fan & Blower(255-E)` catalogue p.36-37
+                // model MF35101V1-1000U-G99 doesn't have a PWM wire, but we'll follow their others models'
+                // recommended frequency, as it is said by the Thermostat's schematics that we can
+                // use PWM, but not stated at which frequency
+                fan_pwm_freq_hz: 25_000,
+                fan_available: true,
+                // see https://github.com/sinara-hw/Thermostat/issues/115 and
+                // https://git.m-labs.hk/M-Labs/thermostat/issues/69#issuecomment-6464 for explanation
+                fan_pwm_recommended: false,
+            },
+            (_, _) => HWSettings {
+                fan_k_a: 0.0,
+                fan_k_b: 0.0,
+                fan_k_c: 0.0,
+                min_fan_pwm: 0.0,
+                max_fan_pwm: 0.0,
+                fan_pwm_freq_hz: 0,
+                fan_available: false,
+                fan_pwm_recommended: false,
+            }
+        }
+    }
+
+    pub fn summary(&self) -> Result<JsonBuffer, serde_json_core::ser::Error> {
+        let settings = self.settings();
+        let summary = HWSummary { rev: self, settings: &settings };
+        serde_json_core::to_vec(&summary)
+    }
+}

src/main.rs

@@ -1,16 +1,14 @@
 #![cfg_attr(not(test), no_std)]
 #![cfg_attr(not(test), no_main)]
-#![feature(maybe_uninit_extra, asm)]
 #![cfg_attr(test, allow(unused))]
 // TODO: #![deny(warnings, unused)]
 
 #[cfg(not(any(feature = "semihosting", test)))]
-use panic_abort as _;
+use panic_halt as _;
 #[cfg(all(feature = "semihosting", not(test)))]
 use panic_semihosting as _;
 
 use log::{error, info, warn};
-
 use cortex_m::asm::wfi;
 use cortex_m_rt::entry;
 use stm32f4xx_hal::{
@@ -54,6 +52,9 @@ mod flash_store;
 mod dfu;
 mod command_handler;
 use command_handler::Handler;
+mod fan_ctrl;
+use fan_ctrl::FanCtrl;
+mod hw_rev;
 
 const HSE: MegaHertz = MegaHertz(8);
 #[cfg(not(feature = "semihosting"))]
@@ -118,8 +119,8 @@ fn main() -> ! {
 
     timer::setup(cp.SYST, clocks);
 
-    let (pins, mut leds, mut eeprom, eth_pins, usb) = Pins::setup(
+    let (pins, mut leds, mut eeprom, eth_pins, usb, fan, hwrev, hw_settings) = Pins::setup(
-        clocks, dp.TIM1, dp.TIM3,
+        clocks, dp.TIM1, dp.TIM3, dp.TIM8,
         dp.GPIOA, dp.GPIOB, dp.GPIOC, dp.GPIOD, dp.GPIOE, dp.GPIOF, dp.GPIOG,
         dp.I2C1,
         dp.SPI2, dp.SPI4, dp.SPI5,
@@ -137,8 +138,7 @@ fn main() -> ! {
 
     let mut store = flash_store::store(dp.FLASH);
 
-
+    let mut channels = Channels::new(pins, &hwrev);
-    let mut channels = Channels::new(pins);
     for c in 0..CHANNELS {
         match store.read_value::<ChannelConfig>(CHANNEL_CONFIG_KEY[c]) {
             Ok(Some(config)) =>
@@ -150,6 +150,8 @@ fn main() -> ! {
         }
     }
 
+    let mut fan_ctrl = FanCtrl::new(fan, hw_settings);
+
     // default net config:
     let mut ipv4_config = Ipv4Config {
         address: [192, 168, 1, 26],
@@ -183,6 +185,14 @@ fn main() -> ! {
                     server.for_each(|_, session| session.set_report_pending(channel.into()));
                 }
 
+                fan_ctrl.cycle(channels.current_abs_max_tec_i());
+
+                if channels.pid_engaged() {
+                    leds.g3.on();
+                } else {
+                    leds.g3.off();
+                }
+
                 let instant = Instant::from_millis(i64::from(timer::now()));
                 cortex_m::interrupt::free(net::clear_pending);
                 server.poll(instant)
@@ -206,7 +216,7 @@ fn main() -> ! {
                                 // Do nothing and feed more data to the line reader in the next loop cycle.
                                 Ok(SessionInput::Nothing) => {}
                                 Ok(SessionInput::Command(command)) => {
-                                    match Handler::handle_command(command, &mut socket, &mut channels, session, &mut leds, &mut store, &mut ipv4_config) {
+                                    match Handler::handle_command(command, &mut socket, &mut channels, session, &mut store, &mut ipv4_config, &mut fan_ctrl, hwrev) {
                                         Ok(Handler::NewIPV4(ip)) => new_ipv4_config = Some(ip),                                
                                         Ok(Handler::Handled) => {},
                                         Ok(Handler::CloseSocket) => socket.close(),

src/pins.rs

@@ -23,7 +23,7 @@ use stm32f4xx_hal::{
         I2C1,
         OTG_FS_GLOBAL, OTG_FS_DEVICE, OTG_FS_PWRCLK,
         SPI2, SPI4, SPI5,
-        TIM1, TIM3,
+        TIM1, TIM3, TIM8
     },
     timer::Timer,
     time::U32Ext,
@@ -33,6 +33,8 @@ use stm32_eth::EthPins;
 use crate::{
     channel::{Channel0, Channel1},
     leds::Leds,
+    fan_ctrl::FanPin,
+    hw_rev::{HWRev, HWSettings},
 };
 
 pub type Eeprom = Eeprom24x<
@@ -64,21 +66,31 @@ pub trait ChannelPins {
     type TecUMeasPin;
 }
 
+pub enum Channel0VRef {
+    Analog(PA0<Analog>),
+    Disabled(PA0<Input<Floating>>),
+}
+
 impl ChannelPins for Channel0 {
     type DacSpi = Dac0Spi;
     type DacSync = PE4<Output<PushPull>>;
     type Shdn = PE10<Output<PushPull>>;
-    type VRefPin = PA0<Analog>;
+    type VRefPin = Channel0VRef;
     type ItecPin = PA6<Analog>;
     type DacFeedbackPin = PA4<Analog>;
     type TecUMeasPin = PC2<Analog>;
 }
 
+pub enum Channel1VRef {
+    Analog(PA3<Analog>),
+    Disabled(PA3<Input<Floating>>),
+}
+
 impl ChannelPins for Channel1 {
     type DacSpi = Dac1Spi;
     type DacSync = PF6<Output<PushPull>>;
     type Shdn = PE15<Output<PushPull>>;
-    type VRefPin = PA3<Analog>;
+    type VRefPin = Channel1VRef;
     type ItecPin = PB0<Analog>;
     type DacFeedbackPin = PA5<Analog>;
     type TecUMeasPin = PC3<Analog>;
@@ -101,6 +113,13 @@ pub struct ChannelPinSet<C: ChannelPins> {
     pub tec_u_meas_pin: C::TecUMeasPin,
 }
 
+pub struct HWRevPins {
+    pub hwrev0: stm32f4xx_hal::gpio::gpiod::PD0<Input<Floating>>,
+    pub hwrev1: stm32f4xx_hal::gpio::gpiod::PD1<Input<Floating>>,
+    pub hwrev2: stm32f4xx_hal::gpio::gpiod::PD2<Input<Floating>>,
+    pub hwrev3: stm32f4xx_hal::gpio::gpiod::PD3<Input<Floating>>,
+}
+
 pub struct Pins {
     pub adc_spi: AdcSpi,
     pub adc_nss: AdcNss,
@@ -114,13 +133,13 @@ impl Pins {
     /// Setup GPIO pins and configure MCU peripherals
     pub fn setup(
         clocks: Clocks,
-        tim1: TIM1, tim3: TIM3,
+        tim1: TIM1, tim3: TIM3, tim8: TIM8,
         gpioa: GPIOA, gpiob: GPIOB, gpioc: GPIOC, gpiod: GPIOD, gpioe: GPIOE, gpiof: GPIOF, gpiog: GPIOG,
         i2c1: I2C1,
         spi2: SPI2, spi4: SPI4, spi5: SPI5,
         adc1: ADC1,
         otg_fs_global: OTG_FS_GLOBAL, otg_fs_device: OTG_FS_DEVICE, otg_fs_pwrclk: OTG_FS_PWRCLK,
-    ) -> (Self, Leds, Eeprom, EthernetPins, USB) {
+    ) -> (Self, Leds, Eeprom, EthernetPins, USB, Option<FanPin>, HWRev, HWSettings) {
         let gpioa = gpioa.split();
         let gpiob = gpiob.split();
         let gpioc = gpioc.split();
@@ -141,13 +160,17 @@ impl Pins {
             gpioe.pe13, gpioe.pe14
         );
 
+        let hwrev = HWRev::detect_hw_rev(&HWRevPins {hwrev0: gpiod.pd0, hwrev1: gpiod.pd1,
+            hwrev2: gpiod.pd2, hwrev3: gpiod.pd3});
+        let hw_settings = hwrev.settings();
+
         let (dac0_spi, dac0_sync) = Self::setup_dac0(
             clocks, spi4,
             gpioe.pe2, gpioe.pe4, gpioe.pe6
         );
         let mut shdn0 = gpioe.pe10.into_push_pull_output();
         let _ = shdn0.set_low();
-        let vref0_pin = gpioa.pa0.into_analog();
+        let vref0_pin = if hwrev.major > 2 {Channel0VRef::Analog(gpioa.pa0.into_analog())} else {Channel0VRef::Disabled(gpioa.pa0)};
         let itec0_pin = gpioa.pa6.into_analog();
         let dac_feedback0_pin = gpioa.pa4.into_analog();
         let tec_u_meas0_pin = gpioc.pc2.into_analog();
@@ -167,7 +190,7 @@ impl Pins {
         );
         let mut shdn1 = gpioe.pe15.into_push_pull_output();
         let _ = shdn1.set_low();
-        let vref1_pin = gpioa.pa3.into_analog();
+        let vref1_pin = if hwrev.major > 2 {Channel1VRef::Analog(gpioa.pa3.into_analog())} else {Channel1VRef::Disabled(gpioa.pa3)};
         let itec1_pin = gpiob.pb0.into_analog();
         let dac_feedback1_pin = gpioa.pa5.into_analog();
         let tec_u_meas1_pin = gpioc.pc3.into_analog();
@@ -215,7 +238,11 @@ impl Pins {
             hclk: clocks.hclk(),
         };
 
-        (pins, leds, eeprom, eth_pins, usb)
+        let fan = if hw_settings.fan_available {
+             Some(Timer::new(tim8, &clocks).pwm(gpioc.pc9.into_alternate(), hw_settings.fan_pwm_freq_hz.hz()))
+        } else { None };
+
+        (pins, leds, eeprom, eth_pins, usb, fan, hwrev, hw_settings)
     }
 
     /// Configure the GPIO pins for SPI operation, and initialize SPI

src/server.rs

@@ -1,4 +1,3 @@
-use core::mem::MaybeUninit;
 use smoltcp::{
     iface::EthernetInterface,
     socket::{SocketSet, SocketHandle, TcpSocket, TcpSocketBuffer, SocketRef},
@@ -13,6 +12,18 @@ pub struct SocketState<S> {
     state: S,
 }
 
+impl<'a, S: Default> SocketState<S>{
+    fn new(sockets: &mut SocketSet<'a>, tcp_rx_storage: &'a mut [u8; TCP_RX_BUFFER_SIZE], tcp_tx_storage: &'a mut [u8; TCP_TX_BUFFER_SIZE]) -> SocketState<S> {
+        let tcp_rx_buffer = TcpSocketBuffer::new(&mut tcp_rx_storage[..]);
+        let tcp_tx_buffer = TcpSocketBuffer::new(&mut tcp_tx_storage[..]);
+        let tcp_socket = TcpSocket::new(tcp_rx_buffer, tcp_tx_buffer);
+        SocketState::<S> {
+            handle: sockets.add(tcp_socket),
+            state: S::default()
+        }
+    }
+}
+
 /// Number of server sockets and therefore concurrent client
 /// sessions. Many data structures in `Server::run()` correspond to
 /// this const.
@@ -35,28 +46,27 @@ impl<'a, 'b, S: Default> Server<'a, 'b, S> {
     where
         F: FnOnce(&mut Server<'a, '_, S>),
     {
-        let mut sockets_storage: [_; SOCKET_COUNT] = Default::default();
+        macro_rules! create_rtx_storage {
-        let mut sockets = SocketSet::new(&mut sockets_storage[..]);
+            ($rx_storage:ident, $tx_storage:ident) => {
-        let mut states: [SocketState<S>; SOCKET_COUNT] = unsafe { MaybeUninit::uninit().assume_init() };
-
-        macro_rules! create_socket {
-            ($set:ident, $rx_storage:ident, $tx_storage:ident, $target:expr) => {
                 let mut $rx_storage = [0; TCP_RX_BUFFER_SIZE];
                 let mut $tx_storage = [0; TCP_TX_BUFFER_SIZE];
-                let tcp_rx_buffer = TcpSocketBuffer::new(&mut $rx_storage[..]);
-                let tcp_tx_buffer = TcpSocketBuffer::new(&mut $tx_storage[..]);
-                let tcp_socket = TcpSocket::new(tcp_rx_buffer, tcp_tx_buffer);
-                $target = $set.add(tcp_socket);
             }
         }
-        create_socket!(sockets, tcp_rx_storage0, tcp_tx_storage0, states[0].handle);
-        create_socket!(sockets, tcp_rx_storage1, tcp_tx_storage1, states[1].handle);
-        create_socket!(sockets, tcp_rx_storage2, tcp_tx_storage2, states[2].handle);
-        create_socket!(sockets, tcp_rx_storage3, tcp_tx_storage3, states[3].handle);
 
-        for state in &mut states {
+        create_rtx_storage!(tcp_rx_storage0, tcp_tx_storage0);
-            state.state = S::default();
+        create_rtx_storage!(tcp_rx_storage1, tcp_tx_storage1);
-        }
+        create_rtx_storage!(tcp_rx_storage2, tcp_tx_storage2);
+        create_rtx_storage!(tcp_rx_storage3, tcp_tx_storage3);
+
+        let mut sockets_storage: [_; SOCKET_COUNT] = Default::default();
+        let mut sockets = SocketSet::new(&mut sockets_storage[..]);
+
+        let states: [SocketState<S>; SOCKET_COUNT] = [
+            SocketState::<S>::new(&mut sockets, &mut tcp_rx_storage0, &mut tcp_tx_storage0),
+            SocketState::<S>::new(&mut sockets, &mut tcp_rx_storage1, &mut tcp_tx_storage1),
+            SocketState::<S>::new(&mut sockets, &mut tcp_rx_storage2, &mut tcp_tx_storage2),
+            SocketState::<S>::new(&mut sockets, &mut tcp_rx_storage3, &mut tcp_tx_storage3),
+        ];
 
         let mut server = Server {
             states,