VFD functionality successfully integrated into Gaugecontroller

CLAUDE.md

@@ -0,0 +1,109 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build & Upload
+
+Main firmware lives in `Gaugecontroller/Gaugecontroller.ino`. Requires the **FastLED** library (`arduino-cli lib install FastLED`). Use the Arduino IDE or `arduino-cli`:
+
+```bash
+# Compile (replace board/port as needed)
+arduino-cli compile --fqbn arduino:avr:mega Gaugecontroller
+
+# Upload
+arduino-cli upload -p /dev/ttyACM0 --fqbn arduino:avr:mega Gaugecontroller
+```
+
+Current default serial setup: `CMD_PORT` and `DEBUG_PORT` both point to `Serial1` at 38400 baud.
+
+## Switching serial ports (debug → production)
+
+Two `#define`s at the top of `Gaugecontroller.ino` control where commands and debug output go:
+
+```cpp
+#define CMD_PORT   Serial1  // command channel (host sends SET, HOME, etc.)
+#define DEBUG_PORT Serial1  // diagnostic prints (homing, boot messages)
+```
+
+**Current default:** both point to `Serial1`, so command and debug traffic share Mega pins TX1=18 / RX1=19 at 38400 baud.
+
+**USB-only debug setup:** point both defines back at `Serial` if you want to talk to the sketch over the Arduino USB port instead:
+
+```cpp
+#define CMD_PORT   Serial
+#define DEBUG_PORT Serial
+```
+
+At that point the matching `begin()` call in `setup()` also needs to use the same baud rate you expect on the host side.
+
+**Split command/debug ports:** if `CMD_PORT` and `DEBUG_PORT` do not point to the same serial port, `setup()` must initialise both. Right now it only calls:
+
+```cpp
+DEBUG_PORT.begin(38400);
+```
+
+If you split them, add a second `CMD_PORT.begin(...)` call.
+
+Arduino Mega hardware UARTs for reference:
+
+| Port    | TX pin | RX pin |
+|---------|--------|--------|
+| Serial1 | 18     | 19     |
+| Serial2 | 16     | 17     |
+| Serial3 | 14     | 15     |
+
+## Architecture
+
+The sketch controls `GAUGE_COUNT` stepper-motor gauges using a trapezoidal velocity profile and a simple text serial protocol.
+
+### Key data structures
+
+- `GaugePins` — hardware pin mapping per gauge (dir, step, enable, active-high/low polarity flags, `ledCount`). Declared `constexpr` so `TOTAL_LEDS` can be computed from it at compile time. Configured in the `gaugePins[]` array at the top.
+- `Gauge` — per-gauge runtime state: position, target, velocity, accel, homing state machine, sweep mode.
+
+### Motion control (`updateGauge`)
+
+Each call to `updateGauge(id)` in `loop()` computes `dt` since last call and updates velocity using a braking-distance check to produce smooth trapezoidal motion. Steps are accumulated as floating-point and emitted via `doStep` when the accumulator crosses ±1.
+
+### Homing sequence (`updateHoming`)
+
+State machine: `HS_START → HS_BACKING → HS_SETTLE → HS_DONE → HS_IDLE`.  
+Backs up `homingBackoffSteps` at `homingSpeed`, waits 100 ms settle, then declares `currentPos = 0`. No physical end-stop is used; homing is purely time/step-count based.
+
+### Sweep mode
+
+When `sweepEnabled`, `updateSweepTarget` bounces `targetPos` between `minPos` and `maxPos` autonomously.
+
+### LED strip
+
+One shared WS2812B strip is driven from `LED_DATA_PIN` (currently 22). Each gauge owns a contiguous segment of the strip; `gaugePins[i].ledCount` sets the segment length (0 = no LEDs). `TOTAL_LEDS` is computed at compile time via `constexpr sumLedCounts()` — no manual constant to keep in sync. Per-gauge offsets into the flat `leds[]` array are computed once in `setup()` into `gaugeLedOffset[]`. LED commands and effects mark the strip dirty, and `FastLED.show()` is called once per main-loop iteration if anything changed.
+
+### Serial command protocol
+
+Commands arrive as newline-terminated ASCII lines. Each `parse*` function in `processLine` handles one command family:
+
+| Command | Syntax | Effect |
+|---|---|---|
+| `SET` | `SET <id> <pos>` | Move gauge to absolute step position |
+| `SPEED` | `SPEED <id> <steps/s>` | Set max speed |
+| `ACCEL` | `ACCEL <id> <steps/s²>` | Set acceleration |
+| `ENABLE` | `ENABLE <id> <0\|1>` | Enable/disable driver output |
+| `ZERO` | `ZERO <id>` | Mark current position as home without moving |
+| `HOME` | `HOME <id>` / `HOMEALL` | Run homing sequence |
+| `SWEEP` | `SWEEP <id> <accel> <speed>` | Start sweep (0/0 stops) |
+| `POS?` | `POS?` | Query all gauges: `POS <id> <cur> <tgt> <homed> <homingState> <sweep>` |
+| `LED` | `LED <id> <idx> <r> <g> <b>` | Set one LED (0-based index within gauge segment) to RGB colour (0–255 each); `<idx>` may be a range `N-M` to set LEDs N through M in one command; also stops any active effect on those LEDs |
+| `LED?` | `LED?` | Query all LEDs: one `LED <id> <idx> <r> <g> <b>` line per LED, then `OK` |
+| `BLINK` | `BLINK <id> <idx> <on_ms> <off_ms> <r> <g> <b>` | Blink LED(s) at given colour; `<idx>` may be a range `N-M`; `on_ms`/`off_ms` both 0 stops blinking. 4-arg form (no colour) uses current LED colour |
+| `BREATHE` | `BREATHE <id> <idx> <period_ms> <r> <g> <b>` | Smooth triangle-wave fade between black and the given colour; `<idx>` may be a range `N-M` |
+| `DFLASH` | `DFLASH <id> <idx> <r> <g> <b>` | Two quick flashes (100 ms on/off each) followed by a 700 ms pause, then repeats; `<idx>` may be a range `N-M` |
+| `PING` | `PING` | Responds `PONG` |
+
+All commands reply `OK` or `ERR BAD_ID` / `ERR BAD_CMD` etc.
+
+### Adding gauges
+
+1. Increment `GAUGE_COUNT`.
+2. Add a `constexpr GaugePins` entry to `gaugePins[]` (including `ledCount`).
+3. Tune `maxPos` and `homingBackoffSteps` in the corresponding `Gauge` default or at runtime.
+4. `TOTAL_LEDS` and `gaugeLedOffset[]` update automatically — no manual changes needed.

Gaugecontroller/Gaugecontroller.ino

@@ -1,27 +1,246 @@
 #include <Arduino.h>
+#include <ctype.h>
 #include <math.h>
+#include <FastLED.h>
 
-static const uint8_t GAUGE_COUNT = 2;
+static const uint8_t GAUGE_COUNT = 3;
 
-// For now: commands come over USB serial
+// One shared WS2812B strip, split into per-gauge segments.
-#define CMD_PORT Serial
+static const uint8_t LED_DATA_PIN = 22;
-#define DEBUG_PORT Serial
+
+// For now, command and debug traffic share the same serial port.
+#define CMD_PORT Serial1
+#define DEBUG_PORT Serial1
+static const unsigned long SERIAL_BAUD = 38400;
+
+namespace vfd {
+
+constexpr uint8_t kDataPin = 46;
+constexpr uint8_t kClockPin = 47;
+constexpr uint8_t kLatchPin = 48;
+constexpr int8_t kBlankPin = 49;   // Set to -1 if BL/OE is not connected
+constexpr bool kBlankActiveHigh = true;
+
+constexpr unsigned long kDigitHoldMicros = 2000;
+constexpr uint8_t kDigitCount = 4;
+constexpr uint8_t kSegmentCount = 7;
+constexpr uint8_t kDriverBits = 20;
+
+constexpr uint8_t kSegmentStartBit = 0;    // HVOut1 -> bit 0
+constexpr uint8_t kPointSegmentBit = 7;    // HVOut8 -> bit 7
+constexpr uint8_t kBellSegmentBit = 8;     // HVOut9 -> bit 8
+constexpr uint8_t kGridStartBit = 9;       // HVOut10 -> bit 9
+constexpr uint8_t kIndicatorGridBit = 13;  // HVOut14 -> bit 13
+
+char displayBuffer[kDigitCount] = {' ', ' ', ' ', ' '};
+bool pointEnabled = false;
+bool bellEnabled = false;
+uint8_t currentPhase = 0;
+
+uint8_t encodeCharacter(char c) {
+  switch (c) {
+    case '0': return 0b0111111;
+    case '1': return 0b0000110;
+    case '2': return 0b1011011;
+    case '3': return 0b1001111;
+    case '4': return 0b1100110;
+    case '5': return 0b1101101;
+    case '6': return 0b1111101;
+    case '7': return 0b0000111;
+    case '8': return 0b1111111;
+    case '9': return 0b1101111;
+    case 'A':
+    case 'a': return 0b1110111;
+    case 'B':
+    case 'b': return 0b1111100;
+    case 'C':
+    case 'c': return 0b0111001;
+    case 'D':
+    case 'd': return 0b1011110;
+    case 'E':
+    case 'e': return 0b1111001;
+    case 'F':
+    case 'f': return 0b1110001;
+    case '-': return 0b1000000;
+    default: return 0;
+  }
+}
+
+void shiftDriverWord(uint32_t word) {
+  digitalWrite(kLatchPin, HIGH);
+  digitalWrite(kClockPin, HIGH);
+
+  for (int8_t bit = kDriverBits - 1; bit >= 0; --bit) {
+    digitalWrite(kDataPin, (word >> bit) & 0x1U ? HIGH : LOW);
+    digitalWrite(kClockPin, LOW);
+    digitalWrite(kClockPin, HIGH);
+  }
+
+  digitalWrite(kLatchPin, LOW);
+  digitalWrite(kLatchPin, HIGH);
+}
+
+void setBlanked(bool blanked) {
+  if (kBlankPin < 0) return;
+
+  const bool level = kBlankActiveHigh ? blanked : !blanked;
+  digitalWrite(kBlankPin, level ? HIGH : LOW);
+}
+
+void writeText(const char* text) {
+  for (uint8_t i = 0; i < kDigitCount; ++i) {
+    displayBuffer[i] = ' ';
+  }
+
+  size_t len = strlen(text);
+  if (len > kDigitCount) {
+    text += len - kDigitCount;
+    len = kDigitCount;
+  }
+
+  const uint8_t start = kDigitCount - len;
+  for (uint8_t i = 0; i < len; ++i) {
+    displayBuffer[start + i] = text[i];
+  }
+}
+
+void clear() {
+  writeText("");
+  pointEnabled = false;
+  bellEnabled = false;
+}
+
+bool parseCommand(const String& command) {
+  char displayText[16];
+  size_t inputIndex = 0;
+  size_t displayIndex = 0;
+
+  if (command.length() == 0) {
+    return false;
+  }
+
+  if (command[inputIndex] == '-') {
+    if (displayIndex + 1 >= sizeof(displayText)) {
+      return false;
+    }
+    displayText[displayIndex++] = command[inputIndex++];
+  }
+
+  const size_t digitStart = inputIndex;
+  while (inputIndex < static_cast<size_t>(command.length()) &&
+         isxdigit(static_cast<unsigned char>(command[inputIndex]))) {
+    if (displayIndex + 1 >= sizeof(displayText)) {
+      return false;
+    }
+    displayText[displayIndex++] = toupper(static_cast<unsigned char>(command[inputIndex]));
+    ++inputIndex;
+  }
+
+  if (inputIndex == digitStart) {
+    return false;
+  }
+
+  bool newPointEnabled = false;
+  bool newBellEnabled = false;
+  while (inputIndex < static_cast<size_t>(command.length())) {
+    if (command[inputIndex] == '.') {
+      newPointEnabled = true;
+    } else if (command[inputIndex] == '!') {
+      newBellEnabled = true;
+    } else {
+      return false;
+    }
+    ++inputIndex;
+  }
+
+  displayText[displayIndex] = '\0';
+  writeText(displayText);
+  pointEnabled = newPointEnabled;
+  bellEnabled = newBellEnabled;
+  return true;
+}
+
+void renderDigit(uint8_t digitIndex) {
+  uint32_t word = 0;
+  const uint8_t segments = encodeCharacter(displayBuffer[digitIndex]);
+
+  for (uint8_t segment = 0; segment < kSegmentCount; ++segment) {
+    if ((segments >> segment) & 0x1U) {
+      word |= (1UL << (kSegmentStartBit + segment));
+    }
+  }
+
+  word |= (1UL << (kGridStartBit + digitIndex));
+  shiftDriverWord(word);
+}
+
+void renderIndicator() {
+  uint32_t word = 1UL << kIndicatorGridBit;
+  if (pointEnabled) {
+    word |= 1UL << kPointSegmentBit;
+  }
+  if (bellEnabled) {
+    word |= 1UL << kBellSegmentBit;
+  }
+  shiftDriverWord(word);
+}
+
+void begin() {
+  pinMode(kDataPin, OUTPUT);
+  pinMode(kClockPin, OUTPUT);
+  pinMode(kLatchPin, OUTPUT);
+  if (kBlankPin >= 0) {
+    pinMode(kBlankPin, OUTPUT);
+  }
+
+  digitalWrite(kDataPin, LOW);
+  digitalWrite(kClockPin, HIGH);
+  digitalWrite(kLatchPin, HIGH);
+  setBlanked(true);
+  writeText("0");
+  shiftDriverWord(0);
+}
+
+void refresh() {
+  setBlanked(true);
+  if (currentPhase < kDigitCount) {
+    renderDigit(currentPhase);
+  } else if (pointEnabled || bellEnabled) {
+    renderIndicator();
+  } else {
+    shiftDriverWord(0);
+  }
+  setBlanked(false);
+  delayMicroseconds(kDigitHoldMicros);
+  setBlanked(true);
+
+  currentPhase = (currentPhase + 1) % (kDigitCount + 1);
+}
+
+}  // namespace vfd
 
 struct GaugePins {
   uint8_t dirPin;
   uint8_t stepPin;
-  int8_t enablePin;          // -1 if unused
+  int8_t enablePin;          // -1 means there is no enable pin
   bool dirInverted;
   bool stepActiveHigh;
   bool enableActiveLow;
+  uint8_t ledCount;          // LEDs assigned to this gauge
 };
 
-GaugePins gaugePins[GAUGE_COUNT] = {
+constexpr GaugePins gaugePins[GAUGE_COUNT] = {
-  // dir, step, en, dirInv, stepHigh, enActiveLow
+  // dir, step, en, dirInv, stepHigh, enActiveLow, leds
-  {50, 51, -1, false, true, true},   // Gauge 0
+  {50, 51, -1, false, true, true, 7},   // Gauge 0
-  {8, 9, -1, true, true, true},   // Gauge 1
+  {8,  9,  -1, true,  true, true, 7},   // Gauge 1
+  {52, 53, -1, false, true, true, 7},   // Gauge 2
 };
 
+constexpr uint8_t sumLedCounts(uint8_t i = 0) {
+  return i >= GAUGE_COUNT ? 0 : gaugePins[i].ledCount + sumLedCounts(i + 1);
+}
+static const uint8_t TOTAL_LEDS = sumLedCounts();
+
 enum HomingState : uint8_t {
   HS_IDLE,
   HS_START,
@@ -35,12 +254,12 @@ struct Gauge {
   long targetPos = 0;
 
   long minPos = 0;
-  long maxPos = 3610;             // adjust to your usable travel
+  long maxPos = 3780;
-  long homingBackoffSteps = 3700; // should exceed reverse travel slightly
+  long homingBackoffSteps = 3800; // Deliberately a touch past full reverse travel.
 
   float velocity = 0.0f;
-  float maxSpeed = 8000.0f;
+  float maxSpeed = 5000.0f;
-  float accel = 9000.0f;
+  float accel = 6000.0f;
   float homingSpeed = 500.0f;
 
   float stepAccumulator = 0.0f;
@@ -58,17 +277,91 @@ struct Gauge {
   bool sweepTowardMax = true;
 };
 
+enum LedFx : uint8_t { FX_BLINK = 0, FX_BREATHE = 1, FX_DFLASH = 2 };
+
+struct BlinkState {
+  bool          active      = false;
+  LedFx         fx          = FX_BLINK;
+  CRGB          onColor;
+  unsigned long lastMs      = 0;
+  uint16_t      onMs        = 500;
+  uint16_t      offMs       = 500;
+  bool          currentlyOn = false;
+  uint16_t      periodMs    = 2000;
+  uint16_t      cyclePos    = 0;
+  uint8_t       dphase      = 0;
+};
+
 Gauge gauges[GAUGE_COUNT];
 String rxLine;
 
+CRGB leds[TOTAL_LEDS];
+uint8_t gaugeLedOffset[GAUGE_COUNT];
+BlinkState blinkState[TOTAL_LEDS];
+bool ledsDirty = false;
+
+// Sends one-line command replies back over the control port.
+//
+// Serial protocol summary.
+//
+// Host -> controller commands (newline-terminated ASCII):
+//   SET <id> <pos>
+//   SPEED <id> <steps_per_s>
+//   ACCEL <id> <steps_per_s2>
+//   ENABLE <id> <0|1>
+//   ZERO <id>
+//   HOME <id>
+//   HOMEALL
+//   SWEEP <id> <accel> <speed>
+//   POS?
+//   LED?
+//   LED <id> <idx|a-b> <r> <g> <b>
+//   BLINK <id> <idx|a-b> <on_ms> <off_ms> [<r> <g> <b>]
+//   BREATHE <id> <idx|a-b> <period_ms> <r> <g> <b>
+//   DFLASH <id> <idx|a-b> <r> <ig> <b>
+//   VFD <text[.!]>
+//   PING
+//
+// Controller -> host replies / events:
+//   READY
+//     Sent once from setup() after boot completes.
+//   OK
+//     Sent after a valid mutating command, and after POS?/LED? once all data lines
+//     for that query have been emitted.
+//   PONG
+//     Sent in response to PING.
+//   ERR BAD_CMD
+//     Sent when a complete line matches no parser.
+//   ERR TOO_LONG
+//     Sent when an input line exceeds the receive buffer limit.
+//   ERR BAD_ID
+//     Sent by commands that take a gauge id when the id is outside 0..GAUGE_COUNT-1.
+//   ERR BAD_SPEED
+//     Sent by SPEED when the requested speed is <= 0.
+//   ERR BAD_ACCEL
+//     Sent by ACCEL when the requested acceleration is <= 0.
+//   ERR BAD_IDX
+//     Sent by LED/BLINK/BREATHE/DFLASH when an LED index or range is invalid.
+//   ERR BAD_TIME
+//     Sent by BLINK/BREATHE when the timing parameter is invalid.
+//   ERR BAD_VFD
+//     Sent by VFD when the text payload is malformed.
+//   POS <id> <currentPos> <targetPos> <homed> <homingState> <sweepEnabled>
+//     Emitted once per gauge before the trailing OK reply to POS?.
+//   LED <id> <idx> <r> <g> <b>
+//     Emitted once per configured LED before the trailing OK reply to LED?.
+//   HOMED <id>
+//     Debug event printed on DEBUG_PORT when a homing sequence settles successfully.
 void sendReply(const String& s) {
   CMD_PORT.println(s);
 }
 
+// Tiny float absolute-value helper to avoid dragging more machinery into the sketch.
 float absf(float x) {
   return (x < 0.0f) ? -x : x;
 }
 
+// Updates the cached enable state and toggles the hardware pin if one exists.
 void setEnable(uint8_t id, bool en) {
   if (id >= GAUGE_COUNT) return;
   gauges[id].enabled = en;
@@ -80,11 +373,13 @@ void setEnable(uint8_t id, bool en) {
   digitalWrite(pin, level ? HIGH : LOW);
 }
 
+// Applies the logical direction after accounting for per-gauge inversion.
 void setDir(uint8_t id, bool forward) {
   bool level = gaugePins[id].dirInverted ? !forward : forward;
   digitalWrite(gaugePins[id].dirPin, level ? HIGH : LOW);
 }
 
+// Emits one step pulse with the polarity expected by the driver.
 void pulseStep(uint8_t id) {
   bool active = gaugePins[id].stepActiveHigh;
   digitalWrite(gaugePins[id].stepPin, active ? HIGH : LOW);
@@ -92,6 +387,7 @@ void pulseStep(uint8_t id) {
   digitalWrite(gaugePins[id].stepPin, active ? LOW : HIGH);
 }
 
+// Moves the motor by one step if the requested direction is still within allowed travel.
 void doStep(uint8_t id, int dir, bool allowPastMin = false) {
   Gauge& g = gauges[id];
   if (!g.enabled) return;
@@ -109,6 +405,7 @@ void doStep(uint8_t id, int dir, bool allowPastMin = false) {
   }
 }
 
+// Arms the homing state machine for one gauge and clears any in-flight motion.
 void requestHome(uint8_t id) {
   if (id >= GAUGE_COUNT) return;
   Gauge& g = gauges[id];
@@ -119,12 +416,14 @@ void requestHome(uint8_t id) {
   g.sweepEnabled = false;
 }
 
+// Starts the same homing sequence on every configured gauge.
 void requestHomeAll() {
   for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
     requestHome(i);
   }
 }
 
+// Advances the simple homing state machine until the gauge is parked at logical zero.
 void updateHoming(uint8_t id) {
   Gauge& g = gauges[id];
   unsigned long nowUs = micros();
@@ -135,6 +434,7 @@ void updateHoming(uint8_t id) {
       return;
 
     case HS_START:
+      // No endstop here; homing just walks back far enough to hit the hard stop.
       g.velocity = 0.0f;
       g.stepAccumulator = 0.0f;
       g.homingStepsRemaining = g.homingBackoffSteps;
@@ -178,6 +478,7 @@ void updateHoming(uint8_t id) {
   }
 }
 
+// Flips the sweep destination when the gauge has settled at either end of travel.
 void updateSweepTarget(uint8_t id) {
   Gauge& g = gauges[id];
   if (!g.sweepEnabled || !g.homed || g.homingState != HS_IDLE) return;
@@ -197,6 +498,7 @@ void updateSweepTarget(uint8_t id) {
   }
 }
 
+// Runs one gauge worth of motion control, including homing and optional sweeping.
 void updateGauge(uint8_t id) {
   Gauge& g = gauges[id];
 
@@ -231,6 +533,7 @@ void updateGauge(uint8_t id) {
   }
 
   float dir = (error > 0) ? 1.0f : (error < 0 ? -1.0f : 0.0f);
+  // Basic trapezoidal profile: brake if the remaining travel is shorter than the stop distance.
   float brakingDistance = (g.velocity * g.velocity) / (2.0f * g.accel + 0.0001f);
 
   if ((float)labs(error) <= brakingDistance) {
@@ -251,6 +554,7 @@ void updateGauge(uint8_t id) {
     g.velocity = dir * 5.0f;
   }
 
+  // Integrate fractional steps until there is enough to emit a real pulse.
   g.stepAccumulator += g.velocity * dt;
 
   while (g.stepAccumulator >= 1.0f) {
@@ -292,6 +596,8 @@ void updateGauge(uint8_t id) {
   }
 }
 
+// Parses `SET <id> <pos>` and updates the target position.
+// Replies: `OK`, `ERR BAD_ID`.
 bool parseSet(const String& line) {
   int id;
   long pos;
@@ -311,6 +617,8 @@ bool parseSet(const String& line) {
   return false;
 }
 
+// Parses `SPEED <id> <speed>` and updates the max step rate.
+// Replies: `OK`, `ERR BAD_ID`, `ERR BAD_SPEED`.
 bool parseSpeed(const String& line) {
   int firstSpace = line.indexOf(' ');
   int secondSpace = line.indexOf(' ', firstSpace + 1);
@@ -334,6 +642,8 @@ bool parseSpeed(const String& line) {
   return true;
 }
 
+// Parses `ACCEL <id> <accel>` and updates the acceleration limit.
+// Replies: `OK`, `ERR BAD_ID`, `ERR BAD_ACCEL`.
 bool parseAccel(const String& line) {
   int firstSpace = line.indexOf(' ');
   int secondSpace = line.indexOf(' ', firstSpace + 1);
@@ -357,6 +667,8 @@ bool parseAccel(const String& line) {
   return true;
 }
 
+// Parses `ENABLE <id> <0|1>` and toggles the selected driver.
+// Replies: `OK`, `ERR BAD_ID`.
 bool parseEnable(const String& line) {
   int id, en;
   if (sscanf(line.c_str(), "ENABLE %d %d", &id, &en) == 2) {
@@ -372,6 +684,8 @@ bool parseEnable(const String& line) {
   return false;
 }
 
+// Parses `ZERO <id>` and declares the current position to be home.
+// Replies: `OK`, `ERR BAD_ID`.
 bool parseZero(const String& line) {
   int id;
   if (sscanf(line.c_str(), "ZERO %d", &id) == 1) {
@@ -393,6 +707,8 @@ bool parseZero(const String& line) {
   return false;
 }
 
+// Parses `HOME <id>` or `HOMEALL` and kicks off the homing sequence.
+// Replies: `OK`, `ERR BAD_ID`. Successful completion later emits debug line `HOMED <id>`.
 bool parseHome(const String& line) {
   int id;
   if (sscanf(line.c_str(), "HOME %d", &id) == 1) {
@@ -415,6 +731,8 @@ bool parseHome(const String& line) {
   return false;
 }
 
+// Parses `SWEEP <id> <accel> <speed>` and enables or disables end-to-end motion.
+// Replies: `OK`, `ERR BAD_ID`.
 bool parseSweep(const String& line) {
   int firstSpace = line.indexOf(' ');
   int secondSpace = line.indexOf(' ', firstSpace + 1);
@@ -451,6 +769,9 @@ bool parseSweep(const String& line) {
   return true;
 }
 
+// Answers `POS?` with current motion state for every gauge.
+// Emits one `POS <id> <cur> <tgt> <homed> <homingState> <sweep>` line per gauge,
+// then replies `OK`.
 bool parsePosQuery(const String& line) {
   if (line == "POS?") {
     for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
@@ -473,6 +794,8 @@ bool parsePosQuery(const String& line) {
   return false;
 }
 
+// Answers the mandatory life question: are you there?
+// Reply: `PONG`.
 bool parsePing(const String& line) {
   if (line == "PING") {
     sendReply("PONG");
@@ -481,6 +804,251 @@ bool parsePing(const String& line) {
   return false;
 }
 
+// Parses `VFD <text>` where <text> is up to four hex characters with optional `.` and `!` suffixes.
+// Replies: `OK`, `ERR BAD_VFD`.
+bool parseVfd(const String& line) {
+  if (line == "VFD") {
+    vfd::clear();
+    sendReply("OK");
+    return true;
+  }
+
+  if (!line.startsWith("VFD ")) return false;
+
+  const String payload = line.substring(4);
+  if (payload.length() == 0) {
+    vfd::clear();
+    sendReply("OK");
+    return true;
+  }
+
+  if (vfd::parseCommand(payload)) {
+    sendReply("OK");
+  } else {
+    sendReply("ERR BAD_VFD");
+  }
+  return true;
+}
+
+// Answers `LED?` with the current RGB values for every configured LED.
+// Emits one `LED <id> <idx> <r> <g> <b>` line per configured LED, then replies `OK`.
+bool parseLedQuery(const String& line) {
+  if (line == "LED?") {
+    for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
+      for (uint8_t j = 0; j < gaugePins[i].ledCount; j++) {
+        const CRGB& c = leds[gaugeLedOffset[i] + j];
+        CMD_PORT.print("LED ");
+        CMD_PORT.print(i);
+        CMD_PORT.print(' ');
+        CMD_PORT.print(j);
+        CMD_PORT.print(' ');
+        CMD_PORT.print(c.r);
+        CMD_PORT.print(' ');
+        CMD_PORT.print(c.g);
+        CMD_PORT.print(' ');
+        CMD_PORT.println(c.b);
+      }
+    }
+    sendReply("OK");
+    return true;
+  }
+  return false;
+}
+
+// Parses `LED <id> <idx|a-b> <r> <g> <b>` and writes static colours.
+// Replies: `OK`, `ERR BAD_ID`, `ERR BAD_IDX`.
+bool parseLed(const String& line) {
+  int id, r, g, b;
+  char idxToken[16];
+  if (sscanf(line.c_str(), "LED %d %15s %d %d %d", &id, idxToken, &r, &g, &b) == 5) {
+    if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID"); return true; }
+    char* dash = strchr(idxToken, '-');
+    int idxFirst = atoi(idxToken);
+    int idxLast  = dash ? atoi(dash + 1) : idxFirst;
+    if (idxFirst < 0 || idxLast >= gaugePins[id].ledCount || idxFirst > idxLast) {
+      sendReply("ERR BAD_IDX"); return true;
+    }
+    CRGB color(constrain(r, 0, 255), constrain(g, 0, 255), constrain(b, 0, 255));
+    for (int i = idxFirst; i <= idxLast; i++) {
+      blinkState[gaugeLedOffset[id] + i].active = false;
+      leds[gaugeLedOffset[id] + i] = color;
+    }
+    ledsDirty = true;
+    sendReply("OK");
+    return true;
+  }
+  return false;
+}
+
+// Parses `BLINK ...` and assigns a simple on/off effect to one LED or a range.
+// Replies: `OK`, `ERR BAD_ID`, `ERR BAD_IDX`, `ERR BAD_TIME`.
+bool parseBlink(const String& line) {
+  int id, onMs, offMs, r, g, b;
+  char idxToken[16];
+  // Optional RGB values let BLINK either reuse or replace the current colour.
+  int count = sscanf(line.c_str(), "BLINK %d %15s %d %d %d %d %d",
+                     &id, idxToken, &onMs, &offMs, &r, &g, &b);
+  if (count != 4 && count != 7) return false;
+
+  if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID"); return true; }
+  char* dash = strchr(idxToken, '-');
+  int idxFirst = atoi(idxToken);
+  int idxLast  = dash ? atoi(dash + 1) : idxFirst;
+  if (idxFirst < 0 || idxLast >= gaugePins[id].ledCount || idxFirst > idxLast) {
+    sendReply("ERR BAD_IDX"); return true;
+  }
+
+  if (onMs == 0 && offMs == 0) {
+    for (int i = idxFirst; i <= idxLast; i++)
+      blinkState[gaugeLedOffset[id] + i].active = false;
+    sendReply("OK");
+    return true;
+  }
+  if (onMs <= 0 || offMs <= 0) { sendReply("ERR BAD_TIME"); return true; }
+
+  CRGB color = (count == 7)
+    ? CRGB(constrain(r, 0, 255), constrain(g, 0, 255), constrain(b, 0, 255))
+    : CRGB(0, 0, 0);  // Placeholder; replaced with the live LED colour below.
+
+  unsigned long nowMs = millis();
+  for (int i = idxFirst; i <= idxLast; i++) {
+    uint8_t globalIdx = gaugeLedOffset[id] + i;
+    BlinkState& bs = blinkState[globalIdx];
+    bs.fx       = FX_BLINK;
+    bs.onColor  = (count == 7) ? color : leds[globalIdx];
+    bs.onMs     = (uint16_t)onMs;
+    bs.offMs    = (uint16_t)offMs;
+    bs.currentlyOn = true;
+    bs.lastMs   = nowMs;
+    bs.active   = true;
+    leds[globalIdx] = bs.onColor;
+  }
+  ledsDirty = true;
+  sendReply("OK");
+  return true;
+}
+
+// Parses `BREATHE ...` and assigns a triangle-wave fade effect.
+// Replies: `OK`, `ERR BAD_ID`, `ERR BAD_IDX`, `ERR BAD_TIME`.
+bool parseBreathe(const String& line) {
+  int id, periodMs, r, g, b;
+  char idxToken[16];
+  if (sscanf(line.c_str(), "BREATHE %d %15s %d %d %d %d",
+             &id, idxToken, &periodMs, &r, &g, &b) != 6) return false;
+  if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID"); return true; }
+  char* dash = strchr(idxToken, '-');
+  int idxFirst = atoi(idxToken);
+  int idxLast  = dash ? atoi(dash + 1) : idxFirst;
+  if (idxFirst < 0 || idxLast >= gaugePins[id].ledCount || idxFirst > idxLast) {
+    sendReply("ERR BAD_IDX"); return true;
+  }
+  if (periodMs <= 0) { sendReply("ERR BAD_TIME"); return true; }
+  CRGB color(constrain(r, 0, 255), constrain(g, 0, 255), constrain(b, 0, 255));
+  unsigned long nowMs = millis();
+  for (int i = idxFirst; i <= idxLast; i++) {
+    uint8_t gi = gaugeLedOffset[id] + i;
+    BlinkState& bs = blinkState[gi];
+    bs.fx       = FX_BREATHE;
+    bs.onColor  = color;
+    bs.periodMs = (uint16_t)constrain(periodMs, 100, 30000);
+    bs.cyclePos = 0;
+    bs.lastMs   = nowMs;
+    bs.active   = true;
+    leds[gi]    = CRGB::Black;
+  }
+  ledsDirty = true;
+  sendReply("OK");
+  return true;
+}
+
+// Parses `DFLASH ...` and assigns the double-flash pattern.
+// Replies: `OK`, `ERR BAD_ID`, `ERR BAD_IDX`.
+bool parseDflash(const String& line) {
+  int id, r, g, b;
+  char idxToken[16];
+  if (sscanf(line.c_str(), "DFLASH %d %15s %d %d %d",
+             &id, idxToken, &r, &g, &b) != 5) return false;
+  if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID"); return true; }
+  char* dash = strchr(idxToken, '-');
+  int idxFirst = atoi(idxToken);
+  int idxLast  = dash ? atoi(dash + 1) : idxFirst;
+  if (idxFirst < 0 || idxLast >= gaugePins[id].ledCount || idxFirst > idxLast) {
+    sendReply("ERR BAD_IDX"); return true;
+  }
+  CRGB color(constrain(r, 0, 255), constrain(g, 0, 255), constrain(b, 0, 255));
+  unsigned long nowMs = millis();
+  for (int i = idxFirst; i <= idxLast; i++) {
+    uint8_t gi = gaugeLedOffset[id] + i;
+    BlinkState& bs = blinkState[gi];
+    bs.fx      = FX_DFLASH;
+    bs.onColor = color;
+    bs.dphase  = 0;
+    bs.lastMs  = nowMs;
+    bs.active  = true;
+    leds[gi]   = color;  // phase 0 = on
+  }
+  ledsDirty = true;
+  sendReply("OK");
+  return true;
+}
+
+// Advances all active LED effects and marks the strip dirty when something changed.
+void updateBlink() {
+  unsigned long nowMs = millis();
+  bool changed = false;
+
+  for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
+    for (uint8_t j = 0; j < gaugePins[i].ledCount; j++) {
+      uint8_t gi = gaugeLedOffset[i] + j;
+      BlinkState& bs = blinkState[gi];
+      if (!bs.active) continue;
+
+      switch (bs.fx) {
+        case FX_BLINK: {
+          uint32_t period = bs.currentlyOn ? bs.onMs : bs.offMs;
+          if ((nowMs - bs.lastMs) >= period) {
+            bs.currentlyOn = !bs.currentlyOn;
+            bs.lastMs = nowMs;
+            leds[gi] = bs.currentlyOn ? bs.onColor : CRGB::Black;
+            changed = true;
+          }
+          break;
+        }
+        case FX_BREATHE: {
+          unsigned long dt = nowMs - bs.lastMs;
+          if (dt < 64) break;
+          uint32_t newPos = (uint32_t)bs.cyclePos + dt;
+          bs.cyclePos = (uint16_t)(newPos % bs.periodMs);
+          bs.lastMs = nowMs;
+          // Cheap triangle wave. It does the job and nobody has complained yet.
+          uint16_t half = bs.periodMs >> 1;
+          uint8_t bri = (bs.cyclePos < half)
+              ? (uint8_t)((uint32_t)bs.cyclePos * 255 / half)
+              : (uint8_t)((uint32_t)(bs.periodMs - bs.cyclePos) * 255 / half);
+          leds[gi] = bs.onColor;
+          leds[gi].nscale8(bri ? bri : 1);
+          changed = true;
+          break;
+        }
+        case FX_DFLASH: {
+          static const uint16_t dur[4] = {100, 100, 100, 700}; // on, off, on, longer off
+          if ((nowMs - bs.lastMs) >= dur[bs.dphase]) {
+            bs.lastMs = nowMs;
+            bs.dphase = (bs.dphase + 1) & 3;
+            leds[gi] = (bs.dphase == 0 || bs.dphase == 2) ? bs.onColor : CRGB::Black;
+            changed = true;
+          }
+          break;
+        }
+      }
+    }
+  }
+
+  if (changed) ledsDirty = true;
+}
+
+// Runs the command parsers in order until one claims the line.
+// Reply: `ERR BAD_CMD` when no parser accepts the line.
 void processLine(const String& line) {
   if (parseSet(line)) return;
   if (parseSpeed(line)) return;
@@ -490,11 +1058,19 @@ void processLine(const String& line) {
   if (parseHome(line)) return;
   if (parseSweep(line)) return;
   if (parsePosQuery(line)) return;
+  if (parseLedQuery(line)) return;
+  if (parseLed(line)) return;
+  if (parseBlink(line)) return;
+  if (parseBreathe(line)) return;
+  if (parseDflash(line)) return;
+  if (parseVfd(line)) return;
   if (parsePing(line)) return;
 
   sendReply("ERR BAD_CMD");
 }
 
+// Reads newline-delimited commands from serial and hands complete lines to the parser.
+// Reply: `ERR TOO_LONG` when the buffered line exceeds the receive limit before newline.
 void readCommands() {
   while (CMD_PORT.available()) {
     char c = (char)CMD_PORT.read();
@@ -515,8 +1091,10 @@ void readCommands() {
   }
 }
 
+// Initialises pins, LED bookkeeping and the initial homing cycle.
+// Reply/event: emits `READY` on CMD_PORT once boot is complete.
 void setup() {
-  DEBUG_PORT.begin(115200);
+  DEBUG_PORT.begin(SERIAL_BAUD);
   DEBUG_PORT.println("Gauge controller booting");
 
   for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
@@ -534,16 +1112,39 @@ void setup() {
     gauges[i].lastUpdateMicros = micros();
   }
 
+  // Flatten the per-gauge LED counts into offsets on the shared strip.
+  uint8_t ledOff = 0;
+  for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
+    gaugeLedOffset[i] = ledOff;
+    ledOff += gaugePins[i].ledCount;
+  }
+  FastLED.addLeds<WS2812B, LED_DATA_PIN, GRB>(leds, TOTAL_LEDS);
+  FastLED.setBrightness(255);
+  FastLED.show();
+
+  vfd::begin();
+
   requestHomeAll();
 
   DEBUG_PORT.println("READY");
+  // Boot-complete handshake for the command channel.
   sendReply("READY");
 }
 
+// Main service loop: ingest commands, advance effects, move gauges, flush LEDs.
 void loop() {
   readCommands();
+  vfd::refresh();
+  updateBlink();
 
   for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
     updateGauge(i);
   }
+  
+  if (ledsDirty) {
+    FastLED.show();
+    ledsDirty = false;
+  }
+
+
 }

VFDStandalone/Pinout.md

@@ -0,0 +1,56 @@
+# Pinout
+
+This project uses an Arduino Mega 2560 with an `HV5812P` high-voltage shift register / latch driver.
+
+The sketch in [VFDStandalone.ino](/home/adebaumann/development/arduino_gauge_controller/VFDStandalone/VFDStandalone.ino:1) currently expects these logic connections.
+
+## Arduino Mega 2560 -> HV5812P
+
+| Mega Pin | Mega Function | HV5812P Signal | Notes |
+|---|---|---|---|
+| `D51` | `MOSI` | `DATA` / `DIN` | Serial data into the HV5812P |
+| `D52` | `SCK` | `CLOCK` / `CLK` | Shift clock |
+| `D53` | `SS` | `LATCH` / `STROBE` | Transfers shifted bits to the outputs |
+| `D49` | GPIO | `BLANK` / `OE` | Optional. Set `kHvBlankPin = -1` in the sketch if unused |
+| `GND` | Ground | Logic `GND` | Mega and HV5812P logic ground must be common |
+
+## HV5812P Outputs -> VFD Tube
+
+| HV5812P Output | Function |
+|---|---|
+| `HVOut1` | Segment `A` |
+| `HVOut2` | Segment `B` |
+| `HVOut3` | Segment `C` |
+| `HVOut4` | Segment `D` |
+| `HVOut5` | Segment `E` |
+| `HVOut6` | Segment `F` |
+| `HVOut7` | Segment `G` |
+| `HVOut8` | Decimal point segment |
+| `HVOut9` | Alarm bell segment |
+| `HVOut10` | Digit grid 1 |
+| `HVOut11` | Digit grid 2 |
+| `HVOut12` | Digit grid 3 |
+| `HVOut13` | Digit grid 4 |
+| `HVOut14` | Indicator grid between digits 2 and 3 |
+
+## Serial Input Format
+
+Examples supported by the sketch:
+
+- `1234` -> digits only
+- `1234.` -> decimal point on
+- `1234!` -> alarm bell on
+- `1234.!` -> decimal point and alarm bell on
+
+## Power and Safety Notes
+
+- The Arduino `5V` pin is for the logic side only.
+- The HV5812P also needs its required logic supply and high-voltage supply per the datasheet.
+- The VFD filament, grid, and segment high-voltage wiring are separate from the Arduino logic pins.
+- Do not connect any high-voltage VFD node directly to the Arduino Mega.
+- If the blanking behavior is inverted on your board, change `kBlankActiveHigh` in the sketch.
+
+## Important
+
+This file names the functional signals on the `HV5812P`, not the package pin numbers.
+If you want a package-pin wiring table too, I can add one once you confirm the exact datasheet variant / package orientation you are using.

VFDStandalone/VFDStandalone.ino

@@ -0,0 +1,342 @@
+// Arduino Mega 2560 + HV5812P VFD driver
+//
+// Tube wiring:
+// - HVOut1..HVOut7  -> digit segments A..G
+// - HVOut8          -> decimal point segment on the indicator grid
+// - HVOut9          -> alarm bell segment on the indicator grid
+// - HVOut10..HVOut13 -> digits 1..4
+// - HVOut14         -> indicator grid between digits 2 and 3
+//
+// Send an integer over the USB serial port and it will be shown on the VFD.
+// Examples:
+//   42<newline>
+//   -17<newline>
+//   1234.<newline>   // enables the decimal point
+//   1234!<newline>   // enables the alarm bell
+//   1234.!<newline>  // enables both
+
+#include <Arduino.h>
+
+namespace {
+
+constexpr uint8_t kHvDataPin = 51;   // MOSI on Mega 2560
+constexpr uint8_t kHvClockPin = 52;  // SCK on Mega 2560
+constexpr uint8_t kHvLatchPin = 53;  // User-configurable latch/strobe pin
+constexpr int8_t kHvBlankPin = 49;   // Set to -1 if BL/OE is not connected
+constexpr bool kBlankActiveHigh = true;
+
+constexpr unsigned long kSerialBaud = 115200;
+constexpr unsigned long kDigitHoldMicros = 2000;
+
+constexpr uint8_t kDigitCount = 4;
+constexpr uint8_t kSegmentCount = 7;
+constexpr uint8_t kDriverBits = 20;
+
+constexpr uint8_t kSegmentStartBit = 0;  // HVOut1 -> bit 0
+constexpr uint8_t kPointSegmentBit = 7;  // HVOut8 -> bit 7
+constexpr uint8_t kBellSegmentBit = 8;   // HVOut9 -> bit 8
+constexpr uint8_t kGridStartBit = 9;     // HVOut10 -> bit 9
+constexpr uint8_t kIndicatorGridBit = 13;  // HVOut14 -> bit 13
+
+char g_displayBuffer[kDigitCount] = {' ', ' ', ' ', ' '};
+char g_inputBuffer[16];
+uint8_t g_inputLength = 0;
+bool g_pointEnabled = false;
+bool g_bellEnabled = false;
+uint8_t g_rawOutput = 0;
+
+// Seven-segment encoding order is A, B, C, D, E, F, G.
+uint8_t encodeCharacter(char c) {
+  switch (c) {
+    case '0': return 0b0111111;
+    case '1': return 0b0000110;
+    case '2': return 0b1011011;
+    case '3': return 0b1001111;
+    case '4': return 0b1100110;
+    case '5': return 0b1101101;
+    case '6': return 0b1111101;
+    case '7': return 0b0000111;
+    case '8': return 0b1111111;
+    case '9': return 0b1101111;
+    case 'A':
+    case 'a': return 0b1110111;
+    case 'B':
+    case 'b': return 0b1111100;
+    case 'C':
+    case 'c': return 0b0111001;
+    case 'D':
+    case 'd': return 0b1011110;
+    case 'E':
+    case 'e': return 0b1111001;
+    case 'F':
+    case 'f': return 0b1110001;
+    case '-': return 0b1000000;
+    default: return 0;
+  }
+}
+
+void shiftDriverWord(uint32_t word) {
+  digitalWrite(kHvLatchPin, HIGH);
+  digitalWrite(kHvClockPin, HIGH);
+
+  for (int8_t bit = kDriverBits - 1; bit >= 0; --bit) {
+    digitalWrite(kHvDataPin, (word >> bit) & 0x1U ? HIGH : LOW);
+    digitalWrite(kHvClockPin, LOW);
+    digitalWrite(kHvClockPin, HIGH);
+  }
+
+  digitalWrite(kHvLatchPin, LOW);
+  digitalWrite(kHvLatchPin, HIGH);
+}
+
+void setDisplayBlanked(bool blanked) {
+  if (kHvBlankPin < 0) {
+    return;
+  }
+
+  const bool level = kBlankActiveHigh ? blanked : !blanked;
+  digitalWrite(kHvBlankPin, level ? HIGH : LOW);
+}
+
+void blankDisplay() {
+  shiftDriverWord(0);
+}
+
+uint32_t maskForHvOutput(uint8_t hvOutput) {
+  if (hvOutput == 0 || hvOutput > kDriverBits) {
+    return 0;
+  }
+
+  return 1UL << (hvOutput - 1);
+}
+
+void renderDigit(uint8_t digitIndex) {
+  uint32_t word = 0;
+  const uint8_t segments = encodeCharacter(g_displayBuffer[digitIndex]);
+
+  for (uint8_t segment = 0; segment < kSegmentCount; ++segment) {
+    if ((segments >> segment) & 0x1U) {
+      word |= (1UL << (kSegmentStartBit + segment));
+    }
+  }
+
+  word |= (1UL << (kGridStartBit + digitIndex));
+  shiftDriverWord(word);
+}
+
+void renderIndicator() {
+  uint32_t word = 1UL << kIndicatorGridBit;
+
+  if (g_pointEnabled) {
+    word |= 1UL << kPointSegmentBit;
+  }
+
+  if (g_bellEnabled) {
+    word |= 1UL << kBellSegmentBit;
+  }
+
+  shiftDriverWord(word);
+}
+
+void writeTextToDisplay(const char* text) {
+  for (uint8_t i = 0; i < kDigitCount; ++i) {
+    g_displayBuffer[i] = ' ';
+  }
+
+  size_t len = strlen(text);
+  if (len > kDigitCount) {
+    text += len - kDigitCount;
+    len = kDigitCount;
+  }
+
+  const uint8_t start = kDigitCount - len;
+  for (uint8_t i = 0; i < len; ++i) {
+    g_displayBuffer[start + i] = text[i];
+  }
+}
+
+void setDisplayFromNumber(long value) {
+  char buffer[16];
+  ltoa(value, buffer, 10);
+  writeTextToDisplay(buffer);
+}
+
+bool parseDisplayCommand(const char* input,
+                         char* displayText,
+                         size_t displayTextSize,
+                         bool& pointEnabled,
+                         bool& bellEnabled) {
+  size_t inputIndex = 0;
+  size_t displayIndex = 0;
+
+  if (input[inputIndex] == '-') {
+    if (displayIndex + 1 >= displayTextSize) {
+      return false;
+    }
+    displayText[displayIndex++] = input[inputIndex++];
+  }
+
+  const size_t digitStart = inputIndex;
+  while (isxdigit(static_cast<unsigned char>(input[inputIndex]))) {
+    if (displayIndex + 1 >= displayTextSize) {
+      return false;
+    }
+    displayText[displayIndex] = toupper(static_cast<unsigned char>(input[inputIndex]));
+    ++displayIndex;
+    ++inputIndex;
+  }
+
+  if (inputIndex == digitStart) {
+    return false;
+  }
+
+  pointEnabled = false;
+  bellEnabled = false;
+
+  while (input[inputIndex] != '\0') {
+    if (input[inputIndex] == '.') {
+      pointEnabled = true;
+    } else if (input[inputIndex] == '!') {
+      bellEnabled = true;
+    } else {
+      return false;
+    }
+    ++inputIndex;
+  }
+
+  displayText[displayIndex] = '\0';
+  return true;
+}
+
+bool parseRawOutputCommand(const char* input, uint8_t& hvOutput) {
+  if (strncmp(input, "RAW ", 4) != 0) {
+    return false;
+  }
+
+  char* endPtr = nullptr;
+  const long parsed = strtol(input + 4, &endPtr, 10);
+  if (*endPtr != '\0' || parsed < 0 || parsed > kDriverBits) {
+    return false;
+  }
+
+  hvOutput = static_cast<uint8_t>(parsed);
+  return true;
+}
+
+void commitSerialBuffer() {
+  if (g_inputLength == 0) {
+    return;
+  }
+
+  g_inputBuffer[g_inputLength] = '\0';
+
+  uint8_t rawOutput = 0;
+  if (parseRawOutputCommand(g_inputBuffer, rawOutput)) {
+    g_rawOutput = rawOutput;
+    if (g_rawOutput == 0) {
+      Serial.println(F("RAW mode OFF"));
+    } else {
+      Serial.print(F("RAW mode: HVOUT"));
+      Serial.println(g_rawOutput);
+    }
+    g_inputLength = 0;
+    return;
+  }
+
+  char displayText[16];
+  bool pointEnabled = false;
+  bool bellEnabled = false;
+  if (parseDisplayCommand(g_inputBuffer, displayText, sizeof(displayText), pointEnabled, bellEnabled)) {
+    g_rawOutput = 0;
+    writeTextToDisplay(displayText);
+    g_pointEnabled = pointEnabled;
+    g_bellEnabled = bellEnabled;
+    Serial.print(F("Displaying: "));
+    Serial.println(displayText);
+    Serial.print(F("Point: "));
+    Serial.println(g_pointEnabled ? F("ON") : F("OFF"));
+    Serial.print(F("Bell: "));
+    Serial.println(g_bellEnabled ? F("ON") : F("OFF"));
+  } else {
+    Serial.print(F("Ignored invalid input: "));
+    Serial.println(g_inputBuffer);
+  }
+
+  g_inputLength = 0;
+}
+
+void pollSerial() {
+  while (Serial.available() > 0) {
+    const char incoming = static_cast<char>(Serial.read());
+
+    if (incoming == '\r' || incoming == '\n') {
+      commitSerialBuffer();
+      continue;
+    }
+
+    if (incoming == '\b' || incoming == 127) {
+      if (g_inputLength > 0) {
+        --g_inputLength;
+      }
+      continue;
+    }
+
+    if (g_inputLength < sizeof(g_inputBuffer) - 1) {
+      g_inputBuffer[g_inputLength++] = incoming;
+    }
+  }
+}
+
+void refreshDisplay() {
+  if (g_rawOutput != 0) {
+    setDisplayBlanked(true);
+    shiftDriverWord(maskForHvOutput(g_rawOutput));
+    setDisplayBlanked(false);
+    delayMicroseconds(kDigitHoldMicros);
+    return;
+  }
+
+  static uint8_t currentPhase = 0;
+
+  setDisplayBlanked(true);
+  if (currentPhase < kDigitCount) {
+    renderDigit(currentPhase);
+  } else if (g_pointEnabled || g_bellEnabled) {
+    renderIndicator();
+  } else {
+    blankDisplay();
+  }
+  setDisplayBlanked(false);
+  delayMicroseconds(kDigitHoldMicros);
+  setDisplayBlanked(true);
+
+  currentPhase = (currentPhase + 1) % (kDigitCount + 1);
+}
+
+}  // namespace
+
+void setup() {
+  pinMode(kHvDataPin, OUTPUT);
+  pinMode(kHvClockPin, OUTPUT);
+  pinMode(kHvLatchPin, OUTPUT);
+  if (kHvBlankPin >= 0) {
+    pinMode(kHvBlankPin, OUTPUT);
+  }
+
+  digitalWrite(kHvDataPin, LOW);
+  digitalWrite(kHvClockPin, HIGH);
+  digitalWrite(kHvLatchPin, HIGH);
+  setDisplayBlanked(true);
+
+  Serial.begin(kSerialBaud);
+  writeTextToDisplay("0");
+  blankDisplay();
+
+  Serial.println(F("HV5812P VFD controller ready."));
+  Serial.println(F("Send an integer followed by newline."));
+}
+
+void loop() {
+  pollSerial();
+  refreshDisplay();
+}

config.example.json

@@ -0,0 +1,59 @@
+{
+  "debug": false,
+
+  "wifi_ssid": "MyNetwork",
+  "wifi_password": "MyPassword",
+
+  "mqtt_broker": "192.168.1.10",
+  "mqtt_port": 1883,
+  "mqtt_user": "mqtt_user",
+  "mqtt_password": "mqtt_password",
+  "mqtt_client_id": "gauge_controller",
+  "mqtt_prefix": "gauges",
+
+  "heartbeat_ms": 10000,
+  "rezero_interval_ms": 3600000,
+
+  "device": {
+    "name": "Selsyn Multi",
+    "model": "Chernobyl Selsyn-inspired gauge",
+    "manufacturer": "AdeBaumann",
+    "area": "Control Panels"
+  },
+
+  "arduino_uart": 1,
+  "arduino_tx_pin": 17,
+  "arduino_rx_pin": 16,
+  "arduino_baud": 115200,
+
+  "gauges": [
+    {
+      "name": "Gauge 1",
+      "entity_name": "Selsyn 1 Power",
+      "min": 0,
+      "max": 7300,
+      "max_steps": 4000,
+      "speed": 5000,
+      "acceleration": 6000,
+      "unit": "W",
+      "leds": {
+        "ws2812_red":   [255, 0, 0],
+        "ws2812_green": [0, 255, 0]
+      }
+    },
+    {
+      "name": "Gauge 2",
+      "entity_name": "Selsyn 2 Power",
+      "min": 0,
+      "max": 7300,
+      "max_steps": 4000,
+      "speed": 5000,
+      "acceleration": 6000,
+      "unit": "W",
+      "leds": {
+        "ws2812_red":   [255, 0, 0],
+        "ws2812_green": [0, 255, 0]
+      }
+    }
+  ]
+}

main.py

@@ -0,0 +1 @@
+import gauge

ota.py

@@ -0,0 +1,474 @@
+"""
+ota.py — Gitea OTA updater for ESP32 / MicroPython
+
+Call ota.update() from boot.py before importing anything else.
+If the update or the subsequent boot fails, the updater retries
+on the next boot rather than bricking the device.
+
+Strategy
+--------
+1. Check if last boot was good (OK flag exists).
+2. If good, fetch remote commit SHA and compare with local — if unchanged,
+   skip file check entirely.
+3. If new commit or failed boot, fetch ota_manifest.txt from the repo
+   to determine which files to sync.
+4. Compare SHA1 hashes with a local manifest (.ota_manifest.json).
+5. Download only changed or missing files, writing to .tmp first.
+6. On success, rename .tmp files into place and update the manifest.
+7. If anything fails mid-update, the manifest is not updated, so the
+   next boot will retry. Partially written .tmp files are cleaned up.
+8. A "safety" flag file (.ota_ok) is written by main.py on successful
+   startup. If it is absent on boot, the previous update is suspected
+   bad — the manifest is wiped so all files are re-fetched cleanly.
+
+Manifest format (ota_manifest.txt)
+---------------------------------
+Each line specifies a file or directory to include:
+    boot.py          # specific file
+    ota.py           # another file
+    selsyn/          # entire directory (trailing slash)
+    lib/             # another directory
+    *.py             # wildcard (matches anywhere)
+    selsyn/*.py      # wildcard in subdirectory
+
+Usage in boot.py
+----------------
+    import ota
+    ota.update()
+    # imports of main etc. go here
+
+Configuration
+-------------
+Edit the block below, or override from a local config file
+(see SETTINGS_FILE).  All settings can be left as module-level
+constants or placed in /ota_config.json:
+    {
+        "gitea_base": "http://git.baumann.gr",
+        "repo_owner": "adebaumann",
+        "repo_name":  "HomeControlPanel",
+        "repo_folder": "firmware",
+        "repo_branch": "main",
+        "api_token":   "nicetry-nothere"
+    }
+"""
+
+import os
+import gc
+import sys
+import ujson
+import urequests
+import utime
+
+# ---------------------------------------------------------------------------
+# Default configuration — override via /ota_config.json
+# ---------------------------------------------------------------------------
+
+GITEA_BASE = "http://git.baumann.gr"  # no trailing slash
+REPO_OWNER = "adrian"
+REPO_NAME = "esp32-gauge"
+REPO_FOLDER = "firmware"  # folder inside repo to sync
+REPO_BRANCH = "main"
+API_TOKEN = None  # set to string for private repos
+
+WIFI_SSID = None
+WIFI_PASSWORD = None
+
+SETTINGS_FILE = "/ota_config.json"
+MANIFEST_FILE = "/.ota_manifest.json"
+OK_FLAG_FILE = "/.ota_ok"
+OTA_MANIFEST = "ota_manifest.txt"
+
+# ---------------------------------------------------------------------------
+# Logging
+# ---------------------------------------------------------------------------
+
+
+def _ts():
+    ms = utime.ticks_ms()
+    return f"{(ms // 3600000) % 24:02d}:{(ms // 60000) % 60:02d}:{(ms // 1000) % 60:02d}.{ms % 1000:03d}"
+
+
+def _log(level, msg):
+    print(f"[{_ts()}] {level:5s}  [OTA] {msg}")
+
+
+def info(msg):
+    _log("INFO", msg)
+
+
+def warn(msg):
+    _log("WARN", msg)
+
+
+def log_err(msg):
+    _log("ERROR", msg)
+
+
+# ---------------------------------------------------------------------------
+# HTTP helpers
+# ---------------------------------------------------------------------------
+
+
+def _headers():
+    h = {"Accept": "application/json"}
+    if API_TOKEN:
+        h["Authorization"] = f"token {API_TOKEN}"
+    return h
+
+
+# ---------------------------------------------------------------------------
+# Config loader
+# ---------------------------------------------------------------------------
+
+
+def load_config():
+    global \
+        GITEA_BASE, \
+        REPO_OWNER, \
+        REPO_NAME, \
+        REPO_FOLDER, \
+        REPO_BRANCH, \
+        API_TOKEN, \
+        WIFI_SSID, \
+        WIFI_PASSWORD
+    try:
+        with open(SETTINGS_FILE) as f:
+            cfg = ujson.load(f)
+        GITEA_BASE = cfg.get("gitea_base", GITEA_BASE)
+        REPO_OWNER = cfg.get("repo_owner", REPO_OWNER)
+        REPO_NAME = cfg.get("repo_name", REPO_NAME)
+        REPO_FOLDER = cfg.get("repo_folder", REPO_FOLDER)
+        REPO_BRANCH = cfg.get("repo_branch", REPO_BRANCH)
+        API_TOKEN = cfg.get("api_token", API_TOKEN)
+        WIFI_SSID = cfg.get("wifi_ssid", WIFI_SSID)
+        WIFI_PASSWORD = cfg.get("wifi_password", WIFI_PASSWORD)
+        info(f"Config loaded from {SETTINGS_FILE}")
+    except OSError:
+        info(f"No {SETTINGS_FILE} found — using defaults")
+    except Exception as e:
+        warn(f"Config parse error: {e} — using defaults")
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _match_pattern(name, pattern):
+    if "*" not in pattern:
+        return name == pattern
+    i, n = 0, len(pattern)
+    j, m = 0, len(name)
+    star = -1
+    while i < n and j < m:
+        if pattern[i] == "*":
+            star = i
+            i += 1
+        elif pattern[i] == name[j]:
+            i += 1
+            j += 1
+        elif star >= 0:
+            i = star + 1
+            j += 1
+        else:
+            return False
+    while i < n and pattern[i] == "*":
+        i += 1
+    return i == n and j == m
+
+
+def _fetch_commit_sha():
+    url = f"{GITEA_BASE}/api/v1/repos/{REPO_OWNER}/{REPO_NAME}/branches/{REPO_BRANCH}"
+    try:
+        r = urequests.get(url, headers=_headers())
+        if r.status_code == 200:
+            data = r.json()
+            r.close()
+            return data.get("commit", {}).get("id")
+        r.close()
+    except Exception as e:
+        log_err(f"Failed to fetch commit: {e}")
+    return None
+
+
+def _fetch_manifest():
+    url = (
+        f"{GITEA_BASE}/api/v1/repos/{REPO_OWNER}/{REPO_NAME}"
+        f"/contents/{OTA_MANIFEST}?ref={REPO_BRANCH}"
+    )
+    try:
+        r = urequests.get(url, headers=_headers())
+        try:
+            if r.status_code == 200:
+                data = r.json()
+                if data.get("content"):
+                    import ubinascii
+
+                    content = ubinascii.a2b_base64(data["content"]).decode()
+                    patterns = [line.strip() for line in content.splitlines()]
+                    return [p for p in patterns if p and not p.startswith("#")]
+            else:
+                warn(f"Manifest not found at {OTA_MANIFEST}")
+        finally:
+            r.close()
+    except Exception as e:
+        log_err(f"Failed to fetch manifest: {e}")
+    return None
+
+
+def _fetch_dir(path):
+    url = (
+        f"{GITEA_BASE}/api/v1/repos/{REPO_OWNER}/{REPO_NAME}"
+        f"/contents/{path}?ref={REPO_BRANCH}"
+    )
+    return _api_get(url)
+
+
+def _api_get(url):
+    """GET a URL and return parsed JSON, or None on failure."""
+    try:
+        r = urequests.get(url, headers=_headers())
+        if r.status_code == 200:
+            data = r.json()
+            r.close()
+            return data
+        warn(f"HTTP {r.status_code} for {url}")
+        r.close()
+    except Exception as e:
+        log_err(f"GET {url} failed: {e}")
+    return None
+
+
+def _download(url, dest_path):
+    """Download url to dest_path. Returns True on success."""
+    tmp = dest_path + ".tmp"
+    try:
+        r = urequests.get(url, headers=_headers())
+        if r.status_code != 200:
+            warn(f"Download failed HTTP {r.status_code}: {url}")
+            r.close()
+            return False
+        with open(tmp, "wb") as f:
+            f.write(r.content)
+        r.close()
+        # Rename into place
+        try:
+            os.remove(dest_path)
+        except OSError:
+            pass
+        os.rename(tmp, dest_path)
+        return True
+    except Exception as e:
+        log_err(f"Download error {url}: {e}")
+        try:
+            os.remove(tmp)
+        except OSError:
+            pass
+        return False
+
+
+def _load_manifest():
+    try:
+        with open(MANIFEST_FILE) as f:
+            return ujson.load(f)
+    except Exception:
+        return {}
+
+
+def _save_manifest(manifest, commit_sha=None):
+    try:
+        with open(MANIFEST_FILE, "w") as f:
+            if commit_sha:
+                manifest["_commit"] = commit_sha
+            ujson.dump(manifest, f)
+    except Exception as e:
+        warn(f"Could not save manifest: {e}")
+
+
+
+def _ok_flag_exists():
+    try:
+        os.stat(OK_FLAG_FILE)
+        return True
+    except OSError:
+        return False
+
+
+def _clear_ok_flag():
+    try:
+        os.remove(OK_FLAG_FILE)
+    except OSError:
+        pass
+
+
+def mark_ok():
+    """
+    Call this from main.py after successful startup.
+    Signals to the OTA updater that the last update was good.
+    """
+    try:
+        with open(OK_FLAG_FILE, "w") as f:
+            f.write("ok")
+    except Exception as e:
+        warn(f"Could not write OK flag: {e}")
+
+
+# ---------------------------------------------------------------------------
+# Core update logic
+# ---------------------------------------------------------------------------
+
+
+def _fetch_file_list():
+    """
+    Returns list of {name, sha, download_url} dicts based on the
+    ota_manifest.txt patterns in the repo folder, or None on failure.
+    """
+    manifest_patterns = _fetch_manifest()
+    if manifest_patterns is None:
+        log_err("No manifest — cannot determine what to fetch")
+        return None
+
+    info(f"Manifest patterns: {manifest_patterns}")
+    files = []
+    visited = set()
+
+    def fetch_matching(entries, patterns):
+        for entry in entries:
+            if entry.get("type") == "dir":
+                for p in patterns:
+                    if p.endswith("/") and entry["name"].startswith(p.rstrip("/")):
+                        sub = _fetch_dir(entry["path"])
+                        if sub:
+                            fetch_matching(sub, patterns)
+                        break
+            else:
+                name = entry["name"]
+                for p in patterns:
+                    p = p.rstrip("/")
+                    if _match_pattern(name, p) or _match_pattern(entry["path"], p):
+                        if entry["path"] not in visited:
+                            visited.add(entry["path"])
+                            files.append(
+                                {
+                                    "name": entry["path"],
+                                    "sha": entry["sha"],
+                                    "download_url": entry["download_url"],
+                                }
+                            )
+                        break
+
+    root = _fetch_dir(REPO_FOLDER)
+    if root is None:
+        return None
+
+    fetch_matching(root, manifest_patterns)
+    return files
+
+
+def _do_update(commit_sha=None):
+    """
+    Fetch file list, download changed files, update manifest.
+    Returns True if all succeeded (or nothing needed updating).
+    """
+    info(
+        f"Checking {GITEA_BASE}/{REPO_OWNER}/{REPO_NAME}/{REPO_FOLDER} @ {REPO_BRANCH}"
+    )
+    file_list = _fetch_file_list()
+    if file_list is None:
+        log_err("Could not fetch file list — skipping update")
+        return False
+
+    info(f"Found {len(file_list)} file(s) to sync")
+    manifest = _load_manifest()
+    updated = []
+    failed = []
+
+    for entry in file_list:
+        name = entry["name"]
+        sha = entry["sha"]
+
+        if manifest.get(name) == sha:
+            info(f"  {name}  up to date")
+            continue
+
+        info(f"  {name}  updating (sha={sha[:8]}...)")
+        gc.collect()
+        ok = _download(entry["download_url"], f"/{name}")
+        if ok:
+            manifest[name] = sha
+            updated.append(name)
+            info(f"  {name}  OK")
+        else:
+            failed.append(name)
+            log_err(f"  {name}  FAILED")
+
+    if failed:
+        log_err(f"Update incomplete — {len(failed)} file(s) failed: {failed}")
+        _save_manifest(manifest, commit_sha)
+        return False
+
+    _save_manifest(manifest, commit_sha)
+
+    if updated:
+        info(f"Update complete — {len(updated)} file(s) updated: {updated}")
+    else:
+        info("All files up to date — nothing to do")
+
+    return True
+
+
+# ---------------------------------------------------------------------------
+# Public entry point
+# ---------------------------------------------------------------------------
+
+
+def update():
+    """
+    Main entry point. Call from boot.py before importing application code.
+
+    - If the OK flag is missing, the previous boot is assumed to have
+      failed — wipes the manifest so everything is re-fetched cleanly.
+    - If the commit hash hasn't changed and last boot was good, skip
+      file comparison entirely.
+    - Runs the update.
+    - Clears the OK flag so main.py must re-assert it on successful start.
+    """
+    info("=" * 40)
+    info("OTA updater starting")
+    info("=" * 40)
+
+    load_config()
+
+    ok_flag = _ok_flag_exists()
+    manifest = _load_manifest()
+
+    if not ok_flag:
+        warn("OK flag missing — last boot may have failed")
+        warn("Re-checking all files, will only download changed ones")
+    else:
+        info("OK flag present — last boot was good")
+
+    commit_sha = _fetch_commit_sha()
+
+    if ok_flag and commit_sha and manifest.get("_commit") == commit_sha:
+        info(f"Commit unchanged ({commit_sha[:8]}) — skipping file check")
+        info("-" * 40)
+        return
+
+    if commit_sha:
+        info(f"Remote commit: {commit_sha[:8]}")
+    else:
+        warn("Could not fetch remote commit — proceeding with file check")
+
+    # Clear the flag now; main.py must call ota.mark_ok() to re-set it
+    _clear_ok_flag()
+
+    success = _do_update(commit_sha)
+
+    if success:
+        info("OTA check complete — booting application")
+    else:
+        warn("OTA check had errors — booting with current files")
+
+    info("-" * 40)
+    gc.collect()

ota_config.example.json

@@ -0,0 +1,9 @@
+{
+    "gitea_base": "http://git.baumann.gr",
+    "repo_owner": "adebaumann",
+    "repo_name": "Selsyn_inspired_gauge",
+    "repo_folder": "",
+    "repo_branch": "main",
+    "wifi_ssid": "YourNetwork",
+    "wifi_password": "YourPassword"
+}

ota_manifest.txt

@@ -0,0 +1 @@
+*.py