Add speed interpolation to display every unit of speed with de/acceleration

.gitignore

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+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json

.gitmodules

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+[submodule "libraries/SevSeg"]
+	path = libraries/SevSeg
+	url = https://github.com/outadoc/SevSeg
+[submodule "libraries/MsTimer2"]
+	path = libraries/MsTimer2
+	url = https://github.com/PaulStoffregen/MsTimer2
+[submodule "libraries/TimerOne"]
+	path = libraries/TimerOne
+	url = https://github.com/PaulStoffregen/TimerOne
+[submodule "libraries/NeoSWSerial"]
+	path = libraries/NeoSWSerial
+	url = https://github.com/SlashDevin/NeoSWSerial
+[submodule "libraries/narcoleptic"]
+	path = libraries/narcoleptic
+	url = https://github.com/brabl2/narcoleptic

dmc_speedometer/dmc_speedometer.ino

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+#include <TimerOne.h>
+#include <MsTimer2.h>
+#include <OBD2UART.h>
+#include <SevSeg.h>
+#include <Narcoleptic.h>
+
+#define STATE_DISCONNECTED 0x0
+#define STATE_CONNECTED    0x2
+
+#define TIMER_INTERVAL_DISP_REFRESH_MS 10
+#define TIMER_INTERVAL_DISP_INC_MS   500
+
+#define PIN_SEG_A  5
+#define PIN_SEG_B  6
+#define PIN_SEG_C  7
+#define PIN_SEG_D  8
+#define PIN_SEG_E  9
+#define PIN_SEG_F  10
+#define PIN_SEG_G  11
+#define PIN_SEG_DP 12
+
+#define PIN_DIG_1 A1
+#define PIN_DIG_2 A2
+
+#define PIN_SPEED_ADJUST 0
+
+//#define MODE_SIMULATION
+
+typedef uint8_t speed_t;
+
+SevSeg sevseg;
+COBD obd;
+
+volatile byte state;
+volatile speed_t target_read_speed;
+
+float modifier;
+
+void setup() {    
+    state = STATE_DISCONNECTED;
+    target_read_speed = 0;
+
+    // Read speed modifier (1.0 keeps raw speed read from OBD)
+    // Play with the potentiometer to adjust to real speed or switch to mph
+    modifier = (float)map(analogRead(PIN_SPEED_ADJUST), 0, 1024, 2000, 18000) / (float)10000.0;
+
+    setup_display();
+
+    // Wait a little for everything to settle before we move on
+    delay(2000);
+
+    setup_timers();
+}
+
+void setup_timers() {
+    Timer1.initialize(TIMER_INTERVAL_DISP_REFRESH_MS * 1000);
+    Timer1.attachInterrupt(isr_refresh_display);
+
+    MsTimer2::set(TIMER_INTERVAL_DISP_INC_MS, isr_display);
+    MsTimer2::start();
+}
+
+void setup_display() {
+    byte numDigits = 2;
+    byte digitPins[] = {PIN_DIG_1, PIN_DIG_2};
+    byte segmentPins[] = {
+        PIN_SEG_A,
+        PIN_SEG_B,
+        PIN_SEG_C,
+        PIN_SEG_D,
+        PIN_SEG_E,
+        PIN_SEG_F,
+        PIN_SEG_G,
+        PIN_SEG_DP
+    };
+    bool resistorsOnSegments = true;
+    byte hardwareConfig = COMMON_CATHODE;
+    bool updateWithDelays = false;
+    bool leadingZeros = false;
+
+    sevseg.begin(hardwareConfig, numDigits, digitPins, segmentPins, 
+        resistorsOnSegments, updateWithDelays, leadingZeros);
+
+    sevseg.blank();
+}
+
+void setup_obd_connection() {
+#ifndef MODE_SIMULATION
+    obd.begin();
+
+    // initialize OBD-II adapter
+    for (;;) {
+        int value;
+        // Try to init and read speed; if we can't do either of them, sleep for a while
+        if (obd.init() && obd.readPID(PID_SPEED, value)) {
+            // Connection established!
+            break;            
+        }
+
+        state = STATE_DISCONNECTED;
+
+        // Enter deep sleep; disable all timers, serial comm., interrupts, etc.
+        obd.enterLowPowerMode();    
+        Narcoleptic.delay(8000);
+        obd.leaveLowPowerMode();
+    }
+#else
+    delay(1000);
+#endif
+
+    state = STATE_CONNECTED;
+}
+
+void loop() {
+    if (state == STATE_DISCONNECTED) {
+        // Clear display if we couldn't read the speed, and try reconnecting
+        sevseg.blank();
+        setup_obd_connection();
+    }
+
+    probe_current_speed();
+}
+
+void isr_display() {
+    // Speed currently displayed; will be incremented to reach target speed
+    static speed_t curr_disp_speed = 0;
+
+    if (state == STATE_DISCONNECTED) {
+        return;        
+    }
+
+    // Make copy of target speed
+    const speed_t target_speed = adjust_speed(target_read_speed);
+
+    // We want to increment speed one by one until we hit the target speed
+    // on a relatively short duration
+    double interval_between_incs = TIMER_INTERVAL_DISP_INC_MS / (abs(target_speed - curr_disp_speed));
+
+    // Enable interrupts for the rest of the procedure,
+    // because we want the display to still be refreshed
+    interrupts();
+
+    if (curr_disp_speed == target_speed) {
+        set_displayed_speed(curr_disp_speed);        
+    }
+
+    // Until we've hit the target speed, increment, display and pause
+    while (curr_disp_speed != target_speed) {
+        if (curr_disp_speed < target_speed) {
+            curr_disp_speed++;
+        } else {
+            curr_disp_speed--;
+        }
+
+        // Display and pause execution for a fixed amount of time between each iteration
+        set_displayed_speed(curr_disp_speed);
+        delay(interval_between_incs);
+    }
+}
+
+// Called every 10 ms
+void isr_refresh_display() {
+    sevseg.refreshDisplay();
+}
+
+speed_t adjust_speed(speed_t speed) {
+    return round(modifier * (float)speed);
+}
+
+void set_displayed_speed(speed_t speed) {
+    if (speed < 100) {
+        sevseg.setNumber(speed, 0);
+    } else {
+        // If the speed is >= 100, truncate display and don't show the hundreds 
+        // (useful when reading in km/h)
+        sevseg.setNumber(speed - 100, 0);
+    }
+}
+
+void probe_current_speed() {
+    if (state == STATE_DISCONNECTED)
+        return;
+
+#ifndef MODE_SIMULATION
+    int value;
+    if (obd.readPID(PID_SPEED, value)) {
+        noInterrupts();
+        target_read_speed = value;
+        interrupts();
+        return;
+    }
+
+    noInterrupts();
+    state = STATE_DISCONNECTED;
+    target_read_speed = 0;
+    interrupts();
+#else
+    delay(50);
+
+    noInterrupts();
+    target_read_speed = (millis() / 1000 * 5) % 99;
+    interrupts();
+#endif
+}