finished power meter and speed meter

ESP32/ADC.cpp

@@ -0,0 +1,29 @@
+#include "ADC.h"
+
+namespace
+{
+	const int8_t calibrationNumValues = sizeof(ADC_calibration)/sizeof(ADC_calibration[0]);
+}
+
+ADC::ADC(int8_t gpioPin)
+	: pin_(gpioPin)
+{
+}
+
+float ADC::read()
+{
+	int16_t rawValue = analogRead(pin_);
+
+	for(int8_t i = 1; i < calibrationNumValues; ++i)
+	{
+		if(i == calibrationNumValues - 1 || ADC_calibration[i].ADC_Value >= rawValue)
+		{
+			const auto& p = ADC_calibration[i - 1];
+			const auto& n = ADC_calibration[i];
+			return (float)(rawValue - p.ADC_Value) / (float)(n.ADC_Value - p.ADC_Value) * (n.MeasuredVoltage - p.MeasuredVoltage) + p.MeasuredVoltage;
+		}
+	}
+
+	// This should never happen if the calibration array contains at least 2 entries
+	return -std::numeric_limits<float>::max();
+}

ESP32/ADC.h

@@ -0,0 +1,33 @@
+#include <Arduino.h>
+
+struct ADC_CalibrationValue
+{
+	float MeasuredVoltage;
+	int16_t ADC_Value;
+};
+
+// To improve ADC precision, these values must be measured with a voltmeter
+// You can use a potentiometer to generate different voltages, measure them, and add an entry with the corresponding ADC value returned by analogRead()
+const ADC_CalibrationValue ADC_calibration[] = {
+	{ 0.118f,	1 },
+	{ 0.343f, 	253 },
+	{ 0.791f, 	801 },
+	{ 1.512f, 	1705 },
+	{ 2.013f,	2306 },
+	{ 2.406f,	2796 },
+	{ 2.606f,	3058 },
+	{ 2.839f,	3423 },
+	{ 2.996f,	3726 },
+	{ 3.16f,	4094 }
+};
+
+class ADC
+{
+public:
+	ADC(int8_t gpioPin);
+
+	float read();
+
+private:
+	int8_t pin_;
+};

ESP32/IDECompat.h

@@ -0,0 +1,5 @@
+#include <Arduino.h>
+
+#ifndef IRAM_ATTR
+#define IRAM_ATTR
+#endif

ESP32/vehicle-monitor.cpp

@@ -1,54 +1,94 @@
 #include <Arduino.h>
+#include "IDECompat.h"
 
 #include <WiFi.h>
 #include <FS.h>
 #include <SPIFFS.h>
 #include <ESPAsyncWebServer.h>
 
+#include "ADC.h"
+
 #include "wifi-credentials.h"
 
 AsyncWebServer server(80);
 
-float averageBatteryVoltage = 0.0f;
+ADC currentSensor(36);
-int16_t batteryVoltage = -1; //in mV
+ADC batterySensor(39);
+const int8_t speedSensorPin = 13;
+const int8_t debugLedPin = 12;
 
-struct ADC_CalibrationValue
+const float wheelDiameterInches = 20;
-{
+const int numImpulsesPerTurn = 2;
-	float Measure;
+const float wheelCircumferenceMeters = wheelDiameterInches * 0.0254f * 3.1415f / (float)numImpulsesPerTurn;
-	int16_t ADC_Value;
+
-};
+int16_t batteryVoltage = -1; // in mV
-
+int16_t batteryCurrent = -1; // in mV
-const ADC_CalibrationValue calibration[] = {
+
-	{ 0.118f,	1 },
+volatile bool debugLedState = true;
-	{ 0.343f, 	253 },
+
-	{ 0.791f, 	801 },
+volatile bool speedSensorState = false;
-	{ 1.512f, 	1705 },
+volatile unsigned long speedSensorRiseTime = 0;
-	{ 2.013f,	2306 },
+volatile unsigned long speedSensorLastImpulseTime = 0;
-	{ 2.406f,	2796 },
+volatile unsigned long speedSensorLastImpulseInterval = (unsigned long)-1; // in milliseconds
-	{ 2.606f,	3058 },
+void IRAM_ATTR onSpeedSensorChange(bool newState)
-	{ 2.839f,	3423 },
-	{ 2.996f,	3726 },
-	{ 3.16f,	4094 }
-};
-const int8_t calibrationNumValues = sizeof(calibration)/sizeof(calibration[0]);
-
-float getCalibratedVoltage(int16_t adcOutput)
 {
-	for(int8_t i = 1; i < calibrationNumValues; ++i)
+	if(speedSensorState == newState) return;
+	unsigned long now = millis();
+	speedSensorState = newState;
+
+	bool magnetDetected = !speedSensorState; // the magnet closes the contact which pulls the pin low
+
+	if(magnetDetected)
+	{
+		speedSensorRiseTime = now;
+	}
+	else
+	{
+		unsigned long impulseDuration = now > speedSensorRiseTime ? now - speedSensorRiseTime : (4294967295 - speedSensorRiseTime) + now; // if now is lower than speedSensorRiseTime, it means millis() has overflowed (happens every 50 days)
+		if(impulseDuration > 1000) return; // impulse was too long, ignore it (maybe magnet stopped near the sensor)
+
+		debugLedState = !debugLedState;
+		digitalWrite(debugLedPin, debugLedState ? HIGH : LOW);
+
+		unsigned long timeSinceLastImpulse = now > speedSensorLastImpulseTime ? now - speedSensorLastImpulseTime : (4294967295 - speedSensorLastImpulseTime) + now;
+		speedSensorLastImpulseTime = now;
+		if(timeSinceLastImpulse > 30 && timeSinceLastImpulse < 4000)
 		{
-		if(i == calibrationNumValues - 1 || calibration[i].ADC_Value >= adcOutput)
+			speedSensorLastImpulseInterval = timeSinceLastImpulse;
+		}
+		else
 		{
-			const auto& p = calibration[i - 1];
+			speedSensorLastImpulseInterval = (unsigned long)-1;
-			const auto& n = calibration[i];
-			return (float)(adcOutput - p.ADC_Value) / (float)(n.ADC_Value - p.ADC_Value) * (n.Measure - p.Measure) + p.Measure;
 		}
 	}
+}
 
-	return -1.0f;
+void IRAM_ATTR onSpeedSensorChange() { onSpeedSensorChange(digitalRead(speedSensorPin) == HIGH); }
+
+float getSpeed()
+{
+	unsigned long now = millis();
+
+	unsigned long lastImpulseInterval = speedSensorLastImpulseInterval;
+	unsigned long lastImpulseTime = speedSensorLastImpulseTime;
+	unsigned long timeSinceLastImpulse = now > lastImpulseTime ? now - lastImpulseTime : (4294967295 - lastImpulseTime) + now;
+
+	unsigned long interval = timeSinceLastImpulse > lastImpulseInterval * 10 / 9 ? timeSinceLastImpulse : lastImpulseInterval;
+
+	float speed = wheelCircumferenceMeters / (float)interval * 1000.0f; // in meters per second
+
+	if(speed < 0.25f) return 0.0f; // if speed is very low (less than 1km/h) it probably means we've stopped
+	return speed;
 }
 
 void setup()
 {
+	pinMode(speedSensorPin, INPUT_PULLUP);
+	attachInterrupt(speedSensorPin, &onSpeedSensorChange, CHANGE);
+
+	pinMode(debugLedPin, OUTPUT);
+	digitalWrite(debugLedPin, debugLedState ? HIGH : LOW);
+
 	Serial.begin(115200);
 
 	if(!SPIFFS.begin(false)){
@@ -70,8 +110,11 @@ void setup()
 
 	server.on("/api/status", HTTP_GET, [](AsyncWebServerRequest *request){
 		int v = batteryVoltage;
+		int c = batteryCurrent;
+		int s = (int)(getSpeed() * 1000.0f + 0.5f);
+
 		char json[128];
-		sprintf(json, "{\"v\":%d,\"c\":1000}", v);
+		sprintf(json, "{\"v\":%d,\"c\":%d,\"s\":%d}", v, c, s);
 		request->send(200, "text/json", json);
 	});
 
@@ -86,22 +129,33 @@ void setup()
 	Serial.println("HTTP server started");
 }
 
-float avgAnalogV = 0.0f;
-
 void loop()
 {
-	const int potPin = 34;
+	const int numSamples = 100;
 
-	const float minV = 0.14f; // 1
+	float averageV = 0.0f;
-	const float maxV = 3.16f; // 4094
+	float averageC = 0.0f;
+	for(int sample = 0; sample < numSamples; ++sample)
+	{
+		delay(1);
+		float v = batterySensor.read();
+		float c = currentSensor.read();
 
-	delay(10);
+		averageV += v;
-	int16_t analogV = analogRead(potPin);
+		averageC += c;
-	float v = getCalibratedVoltage(analogV);
+	}
+
+	averageV /= (float)numSamples;
+	averageC /= (float)numSamples;
 
-	averageBatteryVoltage = averageBatteryVoltage * 0.95f + v * 0.05f;
+	if(averageV < 0.2f) averageV = 0.0f;
-	batteryVoltage = (int16_t)(averageBatteryVoltage * 1000.0f + 0.5f);
 
-	//avgAnalogV = avgAnalogV * 0.9f + (float)analogV * 0.1f;
+	averageV *= 27.000f; // account for voltage divider to retrieve the input voltage
-	//batteryVoltage = (int16_t)(avgAnalogV + 0.5f);
+	averageC = max(0.0f, averageC - 2.5f) / 0.0238f; // convert voltage to current, according to the sensor linear relation
+
+	// TODO: mutex ?
+	batteryVoltage = (int16_t)(averageV * 1000.0f + 0.5f);
+	batteryCurrent = (int16_t)(averageC * 1000.0f + 0.5f);
+
+	delay(10);
 }

WebApp/src/main-page.tsx

@@ -26,6 +26,7 @@ export default class MainPage {
 				<p>Tension batterie : {this.status.batteryVoltage.toFixed(3)}V</p>
 				<p>Courant : {this.status.motorCurrent.toFixed(3)}A</p>
 				<p>Puissance : {(this.status.batteryVoltage * this.status.motorCurrent).toFixed(1)}W</p>
+				<p>Vitesse : {(this.status.speed * 3.6).toFixed(1)}km/h</p>
 			</div>
 			: <p>Chargement...</p>;
 	}

WebApp/src/monitor-api.ts

@@ -3,11 +3,13 @@ import m from 'mithril';
 export interface Status {
 	batteryVoltage: number;
 	motorCurrent: number;
+	speed: number; // in meters per second
 };
 
 interface ApiStatus {
 	v: number;
 	c: number;
+	s: number;
 }
 
 export class MonitorApi {
@@ -21,7 +23,8 @@ export class MonitorApi {
 			await new Promise(resolve => setTimeout(resolve, 200));
 			apiStatus = {
 				v: Math.random() * 20000 + 20000,
-				c: Math.random() * 30000
+				c: Math.random() * 30000,
+				s: Math.random() * 14000
 			}
 			setTimeout(() => m.redraw(), 0);
 		} else {
@@ -33,7 +36,8 @@ export class MonitorApi {
 		
 		return {
 			batteryVoltage: apiStatus.v / 1000,
-			motorCurrent: apiStatus.c / 1000
+			motorCurrent: apiStatus.c / 1000,
+			speed: apiStatus.s / 1000
 		};
 	}
 }

schema/MCU_board/MCU_board.kicad_pcb

@@ -122,11 +122,11 @@
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@@ -462,11 +462,11 @@
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