README.md

@@ -110,8 +110,8 @@ formatted as line-delimited JSON.
 | `pid`                            | Show PID configuration                                               |
 | `pid <0/1> target <deg_celsius>` | Set the PID controller target temperature                            |
 | `pid <0/1> kp <value>`           | Set proportional gain                                                |
-| `pid <0/1> ki <value>`           | Set integral gain                                                    |
+| `pid <0/1> ki <value>`           | Set integral gain (unit: 10 Hz)                                      |
-| `pid <0/1> kd <value>`           | Set differential gain                                                |
+| `pid <0/1> kd <value>`           | Set differential gain (unit: 0.1 seconds)                            |
 | `pid <0/1> output_min <amp>`     | Set mininum output                                                   |
 | `pid <0/1> output_max <amp>`     | Set maximum output                                                   |
 | `pid <0/1> integral_min <value>` | Set integral lower bound                                             |

pytec/plot.py

@@ -44,22 +44,26 @@ series = {
 series_lock = Lock()
 
 quit = False
+last_packet_time = None
 
 def recv_data(tec):
     global last_packet_time
     for data in tec.report_mode():
-        ch0 = data[0]
+        if data['channel'] == 0:
-        series_lock.acquire()
+            series_lock.acquire()
-        try:
+            try:
-            time = ch0['time'] / 1000.0
+                time = data['time'] / 1000.0
+                if last_packet_time:
+                    data['interval'] = time - last_packet_time
+                last_packet_time = time
 
-            for k, s in series.items():
+                for k, s in series.items():
-                if k in ch0:
+                    if k in data:
-                    v = ch0[k]
+                        v = data[k]
-                    if type(v) is float:
+                        if type(v) is float:
-                        s.append(time, v)
+                            s.append(time, v)
-        finally:
+            finally:
-            series_lock.release()
+                series_lock.release()
 
         if quit:
             break

pytec/pytec/client.py

@@ -164,3 +164,4 @@ class Client:
     def load_config(self):
         """Load current configuration from EEPROM"""
         self._command("load")
+

src/channel_state.rs

@@ -1,15 +1,13 @@
-use smoltcp::time::{Duration, Instant};
+use smoltcp::time::Instant;
 use uom::si::{
     f64::{
         ElectricPotential,
         ElectricalResistance,
         ThermodynamicTemperature,
-        Time,
     },
     electric_potential::volt,
     electrical_resistance::ohm,
     thermodynamic_temperature::degree_celsius,
-    time::millisecond,
 };
 use crate::{
     ad7172,
@@ -25,7 +23,6 @@ pub struct ChannelState {
     pub adc_data: Option<u32>,
     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
@@ -42,8 +39,6 @@ impl ChannelState {
             adc_data: None,
             adc_calibration,
             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,
@@ -61,7 +56,6 @@ impl ChannelState {
         } else {
             Some(adc_data)
         };
-        self.adc_interval = now - self.adc_time;
         self.adc_time = now;
     }
 
@@ -69,18 +63,10 @@ impl ChannelState {
     pub fn update_pid(&mut self) -> Option<f64> {
         let temperature = self.get_temperature()?
             .get::<degree_celsius>();
-        let pid_output = self.pid.update(temperature, self.get_adc_interval());
+        let pid_output = self.pid.update(temperature);
         Some(pid_output)
     }
 
-    pub fn get_adc_time(&self) -> Time {
-        Time::new::<millisecond>(self.adc_time.total_millis() as f64)
-    }
-
-    pub fn get_adc_interval(&self) -> Time {
-        Time::new::<millisecond>(self.adc_interval.total_millis() as f64)
-    }
-
     pub fn get_adc(&self) -> Option<ElectricPotential> {
         Some(self.adc_calibration.convert_data(self.adc_data?))
     }

src/channels.rs

@@ -3,7 +3,7 @@ use serde::{Serialize, Serializer};
 use smoltcp::time::Instant;
 use stm32f4xx_hal::hal;
 use uom::si::{
-    f64::{ElectricCurrent, ElectricPotential, ElectricalResistance, Time},
+    f64::{ElectricCurrent, ElectricPotential, ElectricalResistance},
     electric_potential::{millivolt, volt},
     electric_current::ampere,
     electrical_resistance::ohm,
@@ -425,8 +425,7 @@ impl Channels {
         );
         Report {
             channel,
-            time: state.get_adc_time(),
+            time: state.adc_time.total_millis(),
-            interval: state.get_adc_interval(),
             adc: state.get_adc(),
             sens: state.get_sens(),
             temperature: state.get_temperature()
@@ -511,8 +510,7 @@ type JsonBuffer = Vec<u8, U1024>;
 #[derive(Serialize)]
 pub struct Report {
     channel: usize,
-    time: Time,
+    time: i64,
-    interval: Time,
     adc: Option<ElectricPotential>,
     sens: Option<ElectricalResistance>,
     temperature: Option<f64>,

src/pid.rs

@@ -1,8 +1,4 @@
 use serde::{Serialize, Deserialize};
-use uom::si::{
-    f64::Time,
-    time::second,
-};
 
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub struct Parameters {
@@ -49,9 +45,7 @@ impl Controller {
         }
     }
 
-    pub fn update(&mut self, input: f64, time_delta: Time) -> f64 {
+    pub fn update(&mut self, input: f64) -> f64 {
-        let time_delta = time_delta.get::<second>();
-
         // error
         let error = input - self.target;
 
@@ -59,7 +53,7 @@ impl Controller {
         let p = f64::from(self.parameters.kp) * error;
 
         // integral
-        self.integral += f64::from(self.parameters.ki) * error * time_delta;
+        self.integral += f64::from(self.parameters.ki) * error;
         if self.integral < self.parameters.integral_min.into() {
             self.integral = self.parameters.integral_min.into();
         }
@@ -70,10 +64,8 @@ impl Controller {
 
         // derivative
         let d = match self.last_input {
-            None =>
+            None => 0.0,
-                0.0,
+            Some(last_input) => f64::from(self.parameters.kd) * (input - last_input),
-            Some(last_input) =>
-                f64::from(self.parameters.kd) * (input - last_input) / time_delta,
         };
         self.last_input = Some(input);