SilverCory · June 10, 2022 12:39 · Jun 10, 2022 · Jun 10, 2022
diff --git a/bike-emulator.ino b/bike-emulator.ino
@@ -0,0 +1,64 @@
+const int PIN_SPEED_SENSOR_OUT = 12;
+const int PIN_BRAKE_LEVER_OUT = 13;
+
+const int PIN_SLOW_TOUCH_1_IN = 4;
+const int PIN_SLOW_TOUCH_2_IN = 32;
+
+const int THRESHOLD = 30;
+const int MAX_FREQ = 345;
+
+void setup() {
+  Serial.begin(115200);
+  // put your setup code here, to run once:
+  pinMode(PIN_SPEED_SENSOR_OUT, OUTPUT);
+  pinMode(PIN_BRAKE_LEVER_OUT, OUTPUT);
+}
+
+float hz = 1;
+bool out = false;
+unsigned long timer = micros();
+
+void loop() {
+  int iBrake = touchRead(PIN_SLOW_TOUCH_1_IN);
+  int iHardBrake = touchRead(PIN_SLOW_TOUCH_2_IN);
+
+  bool brake = iBrake < THRESHOLD;
+  bool hardBrake = iHardBrake < THRESHOLD;
+  Serial.print("Brake: ");
+  Serial.print(brake);
+  Serial.print(", raw: ");
+  Serial.print(iBrake);
+  Serial.print(", HardBrake: ");
+  Serial.print(hardBrake);
+  Serial.print(", raw: ");
+  Serial.print(iHardBrake);
+  Serial.print(", Hz: ");
+  Serial.println(hz);
+
+  if (brake || hardBrake) {
+    digitalWrite(PIN_BRAKE_LEVER_OUT, true);
+  } else {
+    digitalWrite(PIN_BRAKE_LEVER_OUT, false);
+  }
+
+  if (brake) {
+    hz -= 0.3;
+  } else if (hardBrake) {
+    hz -= 1.3;
+  } else {
+    hz += 0.01;
+    if (hz >= MAX_FREQ) {
+      hz = MAX_FREQ;
+    }
+  }
+  if (hz < 1) {
+    hz = 1;
+  }
+
+  unsigned long now = micros();
+  if (now - timer > (1000000/hz)) { // /2?
+    out = !out;
+    digitalWrite(PIN_SPEED_SENSOR_OUT, out);
+    timer = now;
+  }
+}
diff --git a/ess.ino b/ess.ino
@@ -0,0 +1,141 @@
+const float FREQ_PER_MPH = 2.3; // (2.3 Hz) TODO tuning.
+
+const int PIN_SPEED_SENSOR_IN = 18; // TODO
+const int PIN_BRAKE_LIGHT_IN = 4; // TODO
+
+const int PIN_BRAKE_LIGHT_OVERRIDE_OUT = 22; // For saftey, the brake light won't be disconnected from the normal circuit. (Normally closed) TODO
+const int PIN_INDICATOR_LIGHT_OUT = 23; // TODO
+
+const float STROBE_BRAKE_LIGHT_SPEED_MIN = 30; // (MPH) Pass this speed before arming. Legally this should be 34...
+const float STROBE_HAZARDS_LIGHT_SPEED_ON = 10; // (MPH) If the speed decreases below this speed strobe hazards. Legally this should be on with ABS, but we want to draw attention.
+
+const float DECELLERATION_FIRE_RATE = -15.658; // (MPH/s) ~7 m/s/s
+
+volatile float acceleration;
+volatile float speed;
+volatile bool brakeLightOn = false;
+
+void setup() {
+  Serial.begin(115200);
+  pinMode(PIN_BRAKE_LIGHT_OVERRIDE_OUT, OUTPUT);
+  pinMode(PIN_INDICATOR_LIGHT_OUT, OUTPUT);
+
+  pinMode(PIN_SPEED_SENSOR_IN, INPUT);
+  pinMode(PIN_BRAKE_LIGHT_IN, INPUT);
+
+  digitalWrite(PIN_INDICATOR_LIGHT_OUT, true);
+  digitalWrite(PIN_BRAKE_LIGHT_OVERRIDE_OUT, true);
+  delay(500);
+  digitalWrite(PIN_INDICATOR_LIGHT_OUT, false);
+  digitalWrite(PIN_BRAKE_LIGHT_OVERRIDE_OUT, false);
+  delay(500);
+
+  attachInterrupt(digitalPinToInterrupt(PIN_SPEED_SENSOR_IN), ISR_speed_sensor, CHANGE);
+//  attachInterrupt(digitalPinToInterrupt(PIN_BRAKE_LIGHT_IN), ISR_brake_light, CHANGE);
+}
+
+unsigned long blinkTimer = micros();
+bool brakeState = false;
+bool indicatorState = false;
+
+bool alerting = true;
+bool armed = true;
+void loop() {
+  brakeLightOn = digitalRead(PIN_BRAKE_LIGHT_IN);
+
+  float lAcceleration = acceleration;
+  float lSpeed = speed;
+  bool lBrakeLightOn = brakeLightOn;
+  Serial.print("armed: ");
+  Serial.print(armed);
+  Serial.print(", accel: ");
+  Serial.print(lAcceleration);
+  Serial.print(", brake light: ");
+  Serial.print(lBrakeLightOn);
+  Serial.print(", speed: ");
+  Serial.println(lSpeed);
+  // TODO display?
+  if (armed && lAcceleration < DECELLERATION_FIRE_RATE) {
+    alerting = true;
+  }
+
+  if (alerting) {
+    unsigned long now = micros();
+    if (now - blinkTimer >= 166666) {
+      brakeState = !brakeState;
+      if (lSpeed <= STROBE_HAZARDS_LIGHT_SPEED_ON) {
+        indicatorState = !brakeState;
+      }
+      blinkTimer = now;
+    }
+  }
+
+  if (lSpeed >= 30) armed = true;
+  if (lSpeed < 30) armed = false;
+
+  if (!brakeLightOn) {
+    brakeState = false;
+    indicatorState = false;
+    alerting = false;
+  }
+  // TODO keep indicators flashing 5 seconds after alert.
+
+  digitalWrite(PIN_BRAKE_LIGHT_OVERRIDE_OUT, s(brakeState));
+  digitalWrite(PIN_INDICATOR_LIGHT_OUT, s(indicatorState));
+}
+
+int s(bool in) {
+  if (in) return HIGH;
+  return LOW;
+}
+
+void ISR_brake_light() {
+  brakeLightOn = digitalRead(PIN_BRAKE_LIGHT_IN);
+}
+
+// ============================================================
+//                PWM Speed Sensor Interrupt
+// ============================================================
+volatile bool lastState = false;
+volatile bool switched = false;
+volatile unsigned long timer = micros();
+
+volatile unsigned long accelerationTimer = micros();
+
+// ISR_speed_sensor will measure the pwm period (and thus frequency) using an interrupt.
+// Measures high to high ensuring a low pulse is between them.
+// Improvements? Perhaps ensure we have a timeout between invalid states.
+// Missed states shouldn't be counted since switched will never = true.
+void ISR_speed_sensor() {
+    unsigned long now = micros();
+    bool stateNow = digitalRead(PIN_SPEED_SENSOR_IN);
+
+    if (stateNow == lastState) return;
+
+    if (stateNow) {
+      if (switched) {
+        volatile float lastSpeed = speed;
+        // (60000000us - 50000000us) = 10000000 / 1000000us = 10hz * FREQ_PER_MPH = ~23mph?
+        speed = (1000000.0 / (now - timer)) * FREQ_PER_MPH;
+
+        volatile float deltaT = 1000000.0 / ((float) now - accelerationTimer); // 0.3;
+        volatile float deltaV = speed - lastSpeed; // 4mph - 8.5mph =  -4.5mph
+
+        if (deltaT == 0) {
+          acceleration = 0;
+        } else {
+          acceleration = deltaV/deltaT; // -16/0.3
+        }
+
+        accelerationTimer = now;
+      }
+
+      // Reset and start counting.
+      timer = now;
+      switched = false;
+    } else {
+      switched = true;
+    }
+
+    lastState = stateNow;
+}
No results found