Fix wrong current limit duty cycle calculation

- prev commit assumed 3.3V -> 3A current limit which is wrong
- DUTY_TO_CURRENT_RATE is calculated with the equation given in the datasheet

.gitignore

@@ -1,2 +1,5 @@
 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: `arm-none-eabi-objcopy -O binary thermostat thermostat.bin` (you can skip this step if using the BIN from Hydra)
+* 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)
 * 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

flake.lock

@@ -2,16 +2,16 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1691421349,
-        "narHash": "sha256-RRJyX0CUrs4uW4gMhd/X4rcDG8PTgaaCQM5rXEJOx6g=",
+        "lastModified": 1722791413,
+        "narHash": "sha256-rCTrlCWvHzMCNcKxPE3Z/mMK2gDZ+BvvpEVyRM4tKmU=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "011567f35433879aae5024fc6ec53f2a0568a6c4",
+        "rev": "8b5b6723aca5a51edf075936439d9cd3947b7b2c",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-23.05",
+        "ref": "nixos-24.05",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,7 +1,7 @@
 {
   description = "Firmware for the Sinara 8451 Thermostat";
 
-  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-23.05;
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
   inputs.rust-overlay = { 
     url = "github:oxalica/rust-overlay";
     inputs.nixpkgs.follows = "nixpkgs";
@@ -47,6 +47,7 @@
         '';
 
         dontFixup = true;
+        auditable = false;
       };
     in {
       packages.x86_64-linux = {
@@ -61,7 +62,8 @@
       devShells.x86_64-linux.default = pkgs.mkShellNoCC {
         name = "thermostat-dev-shell";
         packages = with pkgs; [
-          rust openocd dfu-util
+          rust llvm
+          openocd dfu-util rlwrap
           ] ++ (with python3Packages; [
             numpy matplotlib
           ]);

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/channels.rs

@@ -1,4 +1,4 @@
-use core::{cmp::max_by, marker::PhantomData};
+use core::marker::PhantomData;
 use heapless::{consts::U2, Vec};
 use num_traits::Zero;
 use serde::{Serialize, Serializer};
@@ -22,6 +22,7 @@ use crate::{
     pins::{self, Channel0VRef, Channel1VRef},
     steinhart_hart,
 };
+use crate::timer::sleep;
 
 pub enum PinsAdcReadTarget {
     VREF,
@@ -45,6 +46,12 @@ pub const MAX_TEC_V: ElectricPotential = ElectricPotential {
     value: 4.0,
 };
 
+// From datasheet, V_MAX_IPos/INeg = 10 * (I_limit * R_SENSE) 
+const MAX_TEC_I_DUTY_TO_CURRENT_RATE: ElectricCurrent = ElectricCurrent {
+    dimension: PhantomData,
+    units: PhantomData,
+    value: 1.0 / (10.0 * R_SENSE / 3.3),
+};
 // 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,
@@ -269,17 +276,6 @@ impl Channels {
         }
     }
 
-    pub fn read_dac_feedback_until_stable(&mut self, channel: usize, tolerance: ElectricPotential) -> ElectricPotential {
-        let mut prev = self.adc_read(channel, PinsAdcReadTarget::DacVfb, 1);
-        loop {
-            let current = self.adc_read(channel, PinsAdcReadTarget::DacVfb, 1);
-            if (current - prev).abs() < tolerance {
-                return current;
-            }
-            prev = current;
-        }
-    }
-
     /// Calibrates the DAC output to match vref of the MAX driver to reduce zero-current offset of the MAX driver output.
     ///
     /// The thermostat DAC applies a control voltage signal to the CTLI pin of MAX driver chip to control its output current.
@@ -306,7 +302,7 @@ impl Channels {
         let mut start_value = 1;
         let mut best_error = ElectricPotential::new::<volt>(100.0);
 
-        for step in (0..18).rev() {
+        for step in (5..18).rev() {
             let mut prev_value = start_value;
             for value in (start_value..=ad5680::MAX_VALUE).step_by(1 << step) {
                 match channel {
@@ -318,8 +314,9 @@ impl Channels {
                     }
                     _ => unreachable!(),
                 }
+                sleep(10);
 
-                let dac_feedback = self.read_dac_feedback_until_stable(channel, ElectricPotential::new::<volt>(0.001));
+                let dac_feedback = self.adc_read(channel, PinsAdcReadTarget::DacVfb, 64);
                 let error = target_voltage - dac_feedback;
                 if error < ElectricPotential::new::<volt>(0.0) {
                     break;
@@ -394,15 +391,13 @@ impl Channels {
     }
 
     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, MAX_TEC_I)
+        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
     }
 
     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, MAX_TEC_I)
+        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
     }
 
     // Get current passing through TEC
@@ -451,14 +446,14 @@ impl Channels {
 
     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).get::<ratio>();
-        let duty = self.set_pwm(channel, PwmPin::MaxIPos, duty);
+        let duty = (max_i_pos / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
+        let duty: f64 = self.set_pwm(channel, PwmPin::MaxIPos, duty);
         (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).get::<ratio>();
+        let duty = (max_i_neg / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
         let duty = self.set_pwm(channel, PwmPin::MaxINeg, duty);
         (duty * max, max)
     }
@@ -561,9 +556,10 @@ impl Channels {
     }
 
     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))
+        (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()
     }
 }
 

src/command_handler.rs

@@ -345,7 +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 fan!\" }");
+            send_line(socket, b"{ \"warning\": \"this thermostat doesn't have a fan!\" }");
             return Ok(Handler::Handled);
         }
         fan_ctrl.set_auto_mode(false);
@@ -374,7 +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 fan!\" }");
+            send_line(socket, b"{ \"warning\": \"this thermostat doesn't have a fan!\" }");
             return Ok(Handler::Handled);
         }
         fan_ctrl.set_auto_mode(true);

src/main.rs

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

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,
 }