docs: update CLAUDE.md for v2.0 — GaugeConfig, no LEDs, correct serial default

Describes the two-part refactor: gauge_config.h for centralised pin and
motion defaults, and uniform sscanf parsing across all parse* functions.

.gitignore

@@ -32,3 +32,4 @@
 *.out
 *.app
 
+.codex

CLAUDE.md

@@ -4,7 +4,9 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## 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`:
+Main firmware lives in `Gaugecontroller/Gaugecontroller.ino`. No external libraries required on the `Stepper-Only` branch. Use the Arduino IDE or `arduino-cli`:
+
+The ESP32 bridge runs ESPHome; the config is in `gaugecontroller.yaml`.
 
 ```bash
 # Compile (replace board/port as needed)
@@ -14,7 +16,7 @@ arduino-cli compile --fqbn arduino:avr:mega Gaugecontroller
 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.
+Current default serial setup: `CMD_PORT` and `DEBUG_PORT` both point to `Serial` (USB) at 38400 baud.
 
 ## Switching serial ports (debug → production)
 
@@ -25,7 +27,7 @@ Two `#define`s at the top of `Gaugecontroller.ino` control where commands and de
 #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.
+**Current default:** both point to `Serial` (USB), so command and debug traffic go over the Arduino USB port 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:
 
@@ -58,8 +60,8 @@ The sketch controls `GAUGE_COUNT` stepper-motor gauges using a trapezoidal veloc
 
 ### 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.
+- `GaugeConfig` — compile-time config per gauge: pin assignments (dir, step, enable, polarity flags) and motion defaults (minPos, maxPos, homingBackoffSteps, maxSpeed, accel, homingSpeed). All gauges are defined in `gauge_config.h` as `constexpr GaugeConfig gaugeConfigs[]`. `GAUGE_COUNT` is derived automatically from the array length.
-- `Gauge` — per-gauge runtime state: position, target, velocity, accel, homing state machine, sweep mode.
+- `Gauge` — per-gauge runtime state: position, target, velocity, accel, homing state machine, sweep mode. Initialised from `gaugeConfigs[]` in `setup()`.
 
 ### Motion control (`updateGauge`)
 
@@ -74,10 +76,6 @@ Backs up `homingBackoffSteps` at `homingSpeed`, waits 100 ms settle, then declar
 
 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:
@@ -92,18 +90,12 @@ Commands arrive as newline-terminated ASCII lines. Each `parse*` function in `pr
 | `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 |
+| `CFG?` | `CFG?` | Query all gauges: `CFG <id> <maxSpeed> <accel>` per gauge |
-| `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`.
+1. Open `Gaugecontroller/gauge_config.h` and append one row to `gaugeConfigs[]`.
-2. Add a `constexpr GaugePins` entry to `gaugePins[]` (including `ledCount`).
+2. `GAUGE_COUNT` updates automatically — no other changes needed.
-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/gauge_config.h

@@ -0,0 +1,31 @@
+#pragma once
+#include <stdint.h>
+
+struct GaugeConfig {
+  // Hardware
+  uint8_t dirPin;
+  uint8_t stepPin;
+  int8_t  enablePin;       // -1 = no enable pin
+  bool    dirInverted;
+  bool    stepActiveHigh;
+  bool    enableActiveLow;
+
+  // Motion defaults (integers; cast to float in setup())
+  long  minPos;
+  long  maxPos;
+  long  homingBackoffSteps;
+  int   maxSpeed;          // steps/s
+  int   accel;             // steps/s²
+  int   homingSpeed;       // steps/s
+};
+
+constexpr GaugeConfig gaugeConfigs[] = {
+  // dir  step  en   dirInv stpHi  enLow  min   max   backoff  speed  accel  hmSpd
+  {  48,  49,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+  {   8,   9,  -1,  true,  true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+  {  52,  53,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+  {  50,  51,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+};
+
+static const uint8_t GAUGE_COUNT =
+    sizeof(gaugeConfigs) / sizeof(gaugeConfigs[0]);

README.md

@@ -7,7 +7,7 @@ A dedicated gauge controller for Arduinos.
 This repository contains:
 
 - `Gaugecontroller/Gaugecontroller.ino`: the Arduino Mega firmware for the stepper gauges, LEDs, and integrated HV5812-based VFD
-- `gauge.py`: the ESP32 / MicroPython MQTT bridge that exposes the controller to Home Assistant
+- `gaugecontroller.yaml`: the ESPHome-based ESP32 firmware that exposes the gauges and VFD to Home Assistant via the native API
 
 ## VFD Support
 
@@ -48,16 +48,19 @@ Rules:
 - shorter values are right-aligned
 - leading zeroes are preserved if they are part of the input
 
-## Home Assistant Entities
+## Home Assistant Integration
 
-The MQTT bridge publishes Home Assistant discovery entities for the VFD:
+The ESPHome firmware in `gaugecontroller.yaml` exposes entities to Home Assistant via the native API:
 
-- `VFD Display`
+### Gauge Controls
-  text entity for the displayed value
+- Number entities for each gauge's target value (with unit conversion)
-- `VFD Decimal Point`
+- Number entities for speed and acceleration (diagnostic)
-  switch entity
+- Rezero buttons for each gauge and all gauges
-- `VFD Alarm`
+
-  switch entity
+### VFD Display
+- `VFD Display`: text entity for the displayed value
+- `VFD Decimal Point`: switch entity
+- `VFD Alarm`: switch entity
 
 The display is intentionally exposed as a text entity rather than a numeric entity so that:
 
@@ -65,27 +68,12 @@ The display is intentionally exposed as a text entity rather than a numeric enti
 - hexadecimal values like `DEAD` or `BEEF` work
 - clearing the display is possible with an empty value
 
-## MQTT Topics
+### LED Controls
+- RGB light entity for each gauge's backlight with effects (Blink, Breathe, Double Flash)
+- Binary light entities for each gauge's red/green indicators and status lights
 
-Using the configured `mqtt_prefix` from `config.json`, the VFD topics are:
+### Diagnostics
-
+- WiFi signal sensor
-- `<prefix>/vfd/set`
+- Uptime sensor
-- `<prefix>/vfd/state`
+- IP address and SSID text sensors
-- `<prefix>/vfd/decimal_point/set`
+- Arduino Last Message sensor
-- `<prefix>/vfd/decimal_point/state`
-- `<prefix>/vfd/alarm/set`
-- `<prefix>/vfd/alarm/state`
-
-Example with the default prefix `gauges`:
-
-- `gauges/vfd/set`
-- `gauges/vfd/decimal_point/set`
-- `gauges/vfd/alarm/set`
-
-Example payloads:
-
-- publish `0123` to `gauges/vfd/set`
-- publish `ON` to `gauges/vfd/decimal_point/set`
-- publish `OFF` to `gauges/vfd/alarm/set`
-
-The MQTT bridge then converts that into the correct Arduino serial command such as `VFD 0123.`.

Rewire_checklist.md

@@ -183,13 +183,14 @@ Then connect the motor side of that driver to:
 
 according to the driver board you are using.
 
-## 14. Wire The WS2812B LEDs
+## 14. Wire The WS2812 LEDs
 
 Connect:
 
-- `Mega D22` -> `WS2812B DIN`
+- `Mega D22` -> main backlight/status strip `DIN`
-- `5V LED supply` -> `WS2812B 5V`
+- `Mega D36` -> indicator strip `DIN`
-- `WS2812B GND` -> common ground rail
+- `5V LED supply` -> both strip `5V` inputs
+- both strip `GND` inputs -> common ground rail
 
 If the LED chain is long or bright:
 

Stripboard_layout.md

@@ -205,9 +205,10 @@ If `D8` and `D9` come from separate fly wires to the stripboard, keep them in th
 
 Route:
 
-- `D22` -> `WS2812 DIN`
+- `D22` -> main backlight/status strip `DIN`
-- `5V` -> `WS2812 5V`
+- `D36` -> indicator strip `DIN`
-- `GND` -> `WS2812 GND`
+- `5V` -> both strip `5V` inputs
+- `GND` -> both strip `GND` inputs
 
 Keep the LED connector in the low-voltage area.
 

archive/gauge.py

@@ -28,6 +28,16 @@ import gc
 from umqtt.robust import MQTTClient
 from machine import UART
 
+# Activate WiFi driver before any heavy heap allocation so it can claim its
+# contiguous DRAM block before the Python heap fragments the address space.
+# Only activate if not already running (e.g. boot.py may have started it).
+gc.collect()
+_early_wlan = network.WLAN(network.STA_IF)
+if not _early_wlan.active():
+    _early_wlan.active(True)
+del _early_wlan
+gc.collect()
+
 # ---------------------------------------------------------------------------
 # Logging
 # ---------------------------------------------------------------------------
@@ -151,27 +161,19 @@ ARDUINO_TX_PIN = int(_cfg.get("arduino_tx_pin", 17))
 ARDUINO_RX_PIN = int(_cfg.get("arduino_rx_pin", 16))
 ARDUINO_BAUD = int(_cfg.get("arduino_baud", 115200))
 
-_arduino = None
+_arduino = UART(ARDUINO_UART_ID, baudrate=ARDUINO_BAUD, tx=ARDUINO_TX_PIN, rx=ARDUINO_RX_PIN, timeout=10)
-
-
-def _ensure_arduino():
-    global _arduino
-    if _arduino is None:
-        _arduino = UART(ARDUINO_UART_ID, baudrate=ARDUINO_BAUD, tx=ARDUINO_TX_PIN, rx=ARDUINO_RX_PIN, timeout=10)
-    return _arduino
 
 
 def arduino_send(cmd):
     """Send a newline-terminated command to the Arduino."""
-    _ensure_arduino().write((cmd + "\n").encode())
+    _arduino.write((cmd + "\n").encode())
     info(f"Arduino → {cmd}")
 
 
 def arduino_recv():
     """Print any lines waiting in the Arduino RX buffer."""
-    uart = _ensure_arduino()
+    while _arduino.any():
-    while uart.any():
+        line = _arduino.readline()
-        line = uart.readline()
         if line:
             print(f"[{_ts()}] ARDU   {line.decode().strip()}")
 
@@ -538,14 +540,11 @@ _WIFI_CONNECT_ATTEMPTS = 3
 def _reset_wifi_interface():
     global _wifi_sta
     _wifi_sta = network.WLAN(network.STA_IF)
-    if not _wifi_sta.active():
+    if _wifi_sta.active():
-        _wifi_sta.active(True)
+        _wifi_sta.active(False)
-        utime.sleep_ms(500)
+        utime.sleep_ms(200)
-    try:
+    _wifi_sta.active(True)
-        _wifi_sta.disconnect()
+    utime.sleep_ms(500)
-    except Exception:
-        pass
-    utime.sleep_ms(1000)
 
 
 def connect_wifi(ssid, password, timeout_s=15, force_reconnect=False):
@@ -562,8 +561,7 @@ def connect_wifi(ssid, password, timeout_s=15, force_reconnect=False):
     last_error = None
     for attempt in range(_WIFI_CONNECT_ATTEMPTS):
         info(f"WiFi connecting to '{ssid}' (attempt {attempt + 1}/{_WIFI_CONNECT_ATTEMPTS}) ...")
-        if not _wifi_sta.isconnected():
+        _reset_wifi_interface()
-            _reset_wifi_interface()
         try:
             _wifi_sta.connect(ssid, password)
             deadline = utime.time() + timeout_s
@@ -578,7 +576,7 @@ def connect_wifi(ssid, password, timeout_s=15, force_reconnect=False):
             info(f"  SSID    : {ssid}")
             info(f"  MAC     : {mac}")
             info(f"  IP      : {ip}  mask:{mask}  gw:{gw}  dns:{dns}")
-            utime.sleep_ms(2000)
+            utime.sleep_ms(500)
             return ip
         except Exception as e:
             last_error = e
@@ -603,7 +601,7 @@ def check_wifi():
 
     log_err("WiFi lost connection — attempting reconnect...")
     try:
-        ip = connect_wifi(WIFI_SSID, WIFI_PASSWORD, timeout_s=15)
+        ip = connect_wifi(WIFI_SSID, WIFI_PASSWORD, timeout_s=15, force_reconnect=True)
         info(f"WiFi reconnected! IP:{ip}")
     except Exception as e:
         log_err(f"WiFi reconnect failed: {e}")
@@ -913,6 +911,10 @@ def connect_mqtt():
         except Exception as e:
             last_error = e
             log_err(f"MQTT connect attempt {attempt + 1} failed: {type(e).__name__}: {e}")
+            try:
+                client.sock.close()
+            except Exception:
+                pass
             gc.collect()
             utime.sleep_ms(1000)
 
@@ -920,6 +922,27 @@ def connect_mqtt():
     raise last_error
 
 
+_mqtt_check_interval_ms = 30000
+_last_mqtt_check = 0
+_discovery_queue = []
+_discovery_idx = 0
+_last_discovery_ms = 0
+_DISCOVERY_INTERVAL_MS = 350
+
+
+def _compact_discovery_payload(payload):
+    """Trim optional HA discovery fields when RAM is tight."""
+    compact = dict(payload)
+
+    # Light entities are the largest payloads because they repeat effect metadata.
+    # Keep core functionality, but omit optional effect declarations to reduce heap use.
+    if compact.get("schema") == "json":
+        compact.pop("effect", None)
+        compact.pop("effect_list", None)
+
+    return compact
+
+
 def check_mqtt():
     global client_ref, _mqtt_connected, _last_mqtt_check
     now = utime.ticks_ms()
@@ -961,6 +984,10 @@ def check_mqtt():
             return True
         except Exception as e2:
             log_err(f"MQTT reconnect attempt {attempt + 1} failed: {e2}")
+            try:
+                client_ref.sock.close()
+            except Exception:
+                pass
             gc.collect()
             utime.sleep_ms(2000)
 
@@ -968,17 +995,9 @@ def check_mqtt():
     return False
 
 
-_mqtt_check_interval_ms = 30000
-_last_mqtt_check = 0
-_discovery_queue = []
-_discovery_idx = 0
-_last_discovery_ms = 0
-_DISCOVERY_INTERVAL_MS = 350
-
-
 def _publish_discovery_entity(client, topic, payload, log_msg):
     gc.collect()
-    client.publish(topic, ujson.dumps(payload), retain=True)
+    client.publish(topic, ujson.dumps(_compact_discovery_payload(payload)), retain=True)
     info(log_msg)
 
 
@@ -1286,42 +1305,12 @@ def apply_motion_defaults():
     send_vfd_state()
 
 
-def _restore_led_states():
-    for i in range(num_gauges):
-        gt = gauge_topics[i]
-        info(f"  red={_red_effect[i]} green={_green_effect[i]} status_r={_status_red_effect[i]} status_g={_status_green_effect[i]}")
-        for led_key, led_idx, color, effect_arr, state_topic in [
-            ("red", _LED_RED, gauges[i]["ws2812_red"], _red_effect, gt["led_red_state"]),
-            ("green", _LED_GREEN, gauges[i]["ws2812_green"], _green_effect, gt["led_green_state"]),
-            ("status_red", _LED_STATUS_RED, gauges[i]["ws2812_red"], _status_red_effect, gt["status_red_state"]),
-            ("status_green", _LED_STATUS_GREEN, gauges[i]["ws2812_green"], _status_green_effect, gt["status_green_state"]),
-        ]:
-            if effect_arr[i]:
-                pub = {"state": "ON", "effect": effect_arr[i]}
-                _publish(state_topic, ujson.dumps(pub), retain=True)
-        if _red_effect[i]:
-            _apply_blink_or_led(i, _LED_RED, gauges[i]["ws2812_red"], _red_effect[i])
-        if _green_effect[i]:
-            _apply_blink_or_led(i, _LED_GREEN, gauges[i]["ws2812_green"], _green_effect[i])
-        if _status_red_effect[i]:
-            _apply_blink_or_led(i, _LED_STATUS_RED, gauges[i]["ws2812_red"], _status_red_effect[i])
-        if _status_green_effect[i]:
-            _apply_blink_or_led(i, _LED_STATUS_GREEN, gauges[i]["ws2812_green"], _status_green_effect[i])
-
-
 # ---------------------------------------------------------------------------
 # Main
 # ---------------------------------------------------------------------------
 
 
 def main():
-    gc.collect()
-    _w = network.WLAN(network.STA_IF)
-    if not _w.active():
-        _w.active(True)
-    del _w
-    gc.collect()
-    _ensure_arduino()
     gc.collect()
     info("=" * 48)
     info("Gauge MQTT controller starting")
@@ -1329,7 +1318,7 @@ def main():
     info("=" * 48)
 
     gc.collect()
-    connect_wifi(WIFI_SSID, WIFI_PASSWORD)
+    connect_wifi(WIFI_SSID, WIFI_PASSWORD, force_reconnect=True)
 
     mqtt_attempts = 0
     while True:
@@ -1342,14 +1331,13 @@ def main():
             if mqtt_attempts % 3 == 0:
                 log_err("WiFi may be stale — forcing reconnect...")
                 try:
-                    connect_wifi(WIFI_SSID, WIFI_PASSWORD)
+                    connect_wifi(WIFI_SSID, WIFI_PASSWORD, force_reconnect=True)
                 except Exception as we:
                     log_err(f"WiFi reconnect failed: {we}")
             utime.sleep_ms(5000)
     _subscribe_all(client_ref)
     schedule_discovery()
 
-    publish_backlight_states(client_ref)
     apply_motion_defaults()
     info("Draining initial retained messages...")
     for _ in range(50):
@@ -1362,10 +1350,6 @@ def main():
         gauge_last_rezero[i] = utime.ticks_ms()
     info("Home command sent")
 
-    utime.sleep_ms(100)
-    _restore_led_states()
-    info("LED effects restored")
-
     info("Publishing state...")
     publish_online(client_ref)
     publish_state(client_ref)

boot.py

@@ -1,62 +0,0 @@
-"""
-boot.py — runs before main.py on every ESP32 boot
-
-Connects WiFi, runs OTA update, then hands off to main.py.
-Keep this file as simple as possible — it is never OTA-updated itself
-(it lives outside the repo folder) so bugs here require USB to fix.
-"""
-#import gauge
-import network
-import gc
-import utime
-import sys
-
-import ota
-
-ota.load_config()
-WIFI_SSID, WIFI_PASSWORD = ota.WIFI_SSID, ota.WIFI_PASSWORD
-
-def _connect_wifi(timeout_s=20):
-    sta = network.WLAN(network.STA_IF)
-    sta.active(True)
-    sta.config(txpower=15)
-    if sta.isconnected():
-        return True
-    sta.connect(WIFI_SSID, WIFI_PASSWORD)
-    deadline = utime.time() + timeout_s
-    while not sta.isconnected():
-        if utime.time() > deadline:
-            return False
-        utime.sleep_ms(300)
-    return True
-
-if WIFI_SSID is None:
-    print("[boot] No WiFi credentials — cannot connect, skipping OTA")
-elif _connect_wifi():
-    ip = network.WLAN(network.STA_IF).ifconfig()[0]
-    print(f"[boot] WiFi connected — {ip}")
-
-    try:
-        ota.update()
-    except Exception as e:
-        print(f"[boot] OTA error: {e} — continuing with existing files")
-        sys.print_exception(e)
-    utime.sleep_ms(5000)
-    ota._fetch_commit_sha = None
-    ota._fetch_manifest = None
-    ota._fetch_dir = None
-    ota._api_get = None
-    ota._download = None
-    ota.urequests = None
-    del ota.urequests
-    del ota
-    gc.collect()
-    del sys.modules["ota"]
-    gc.collect()
-
-else:
-    print("[boot] WiFi failed — skipping OTA, booting with existing files")
-
-# main.py runs automatically after boot.py
-
-

changes.md

@@ -0,0 +1,46 @@
+# Changes
+
+## 2026-04-27 — Arduino firmware refactor (`Gaugecontroller/Gaugecontroller.ino`)
+
+### Non-blocking VFD multiplexer
+`vfd::refresh()` previously held each digit for 2000 µs via `delayMicroseconds`,
+which capped the effective stepper pulse rate at roughly 500 Hz regardless of
+`maxSpeed`. It now tracks `phaseStartMicros`/`phaseActive` and returns
+immediately while the digit is still being held; the main loop runs at
+microsecond cadence again and the configured `maxSpeed = 4000.0f` steps/s is
+actually achievable.
+
+### Fixed-buffer command parser (no more `String` heap churn)
+Replaced `String rxLine` with `char rxBuf[128]` and converted the entire
+command pipeline to take `const char*`:
+
+- `processLine`, `sendReply`, `vfd::parseCommand`
+- All `parse*` functions: `parseSet`, `parseSpeed`, `parseAccel`, `parseEnable`,
+  `parseZero`, `parseHome`, `parseSweep`, `parsePosQuery`, `parseCfgQuery`,
+  `parseLedQuery`, `parseLed`, `parseBlink`, `parseBreathe`, `parseDflash`,
+  `parseVfd`, `parsePing`.
+
+`parseSpeed` / `parseAccel` / `parseSweep` use `strncmp` + `atof` because the
+default AVR-libc `sscanf` doesn't support `%f`. No allocations on the command
+path; the Mega's heap no longer fragments over time.
+
+### Cached `ledNeedsSwap[TOTAL_LEDS]`
+Per-LED RGB-vs-GRB swap flag is now precomputed once in `setup()` from
+`gaugePins[].ledOrder`. `encodeForStrip` is a single array index instead of
+walking the gauge table on every LED read/write.
+
+### Cached step direction per gauge
+Added `Gauge.lastDir`. `setDir()` skips the DIR-pin `digitalWrite` when the
+direction hasn't flipped (the common case during a step run) and adds a 1 µs
+DIR-to-STEP setup delay only when it actually flips.
+
+### Cleanups
+- Removed the `absf` helper; use `fabsf` consistently.
+- Removed the `+ 0.0001f` epsilon in the trapezoidal braking-distance divisor.
+  `parseAccel` already rejects `accel <= 0`, so the divisor is always positive.
+- Fixed the `<r> <ig> <b>` typo to `<r> <g> <b>` in the protocol comment for
+  `DFLASH`.
+
+### Build verification
+`arduino-cli compile --fqbn arduino:avr:mega Gaugecontroller`:
+17758 B flash (6%), 1845 B SRAM (22%).

docs/superpowers/plans/2026-05-21-gaugecontroller-v2.md

@@ -0,0 +1,474 @@
+# Gaugecontroller v2.0 Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Centralise all gauge configuration in `gauge_config.h` and make the three inconsistently-written parsers use `sscanf` like the rest.
+
+**Architecture:** A new header file holds one `constexpr GaugeConfig` table — pin assignments and motion defaults merged — and derives `GAUGE_COUNT` from its length. The sketch includes this header, removes the old `GaugePins` struct and all hardcoded defaults, and initialises `Gauge` runtime state from the table in `setup()`. Three parse functions are then rewritten from manual string splitting to `sscanf`.
+
+**Tech Stack:** Arduino (AVR/Mega), `arduino-cli`, C++11 `constexpr`.
+
+> **Note on testing:** This is a bare-metal Arduino sketch with no unit-test framework. Each task's verification step is a clean compile with `arduino-cli`. Functional testing requires the physical hardware; the plan notes what to check over serial when hardware is available.
+
+---
+
+## File Map
+
+| File | Action | Responsibility |
+|---|---|---|
+| `Gaugecontroller/gauge_config.h` | **Create** | All pin assignments and motion defaults; `GAUGE_COUNT` |
+| `Gaugecontroller/Gaugecontroller.ino` | **Modify** | Remove `GaugePins`, add include, strip `Gauge` defaults, update all references, rewrite 3 parsers |
+
+---
+
+## Task 1: Create `gauge_config.h`
+
+**Files:**
+- Create: `Gaugecontroller/gauge_config.h`
+
+- [ ] **Step 1: Create the file**
+
+  Create `Gaugecontroller/gauge_config.h` with the following content:
+
+  ```cpp
+  #pragma once
+  #include <stdint.h>
+
+  struct GaugeConfig {
+    // Hardware
+    uint8_t dirPin;
+    uint8_t stepPin;
+    int8_t  enablePin;       // -1 = no enable pin
+    bool    dirInverted;
+    bool    stepActiveHigh;
+    bool    enableActiveLow;
+
+    // Motion defaults (integers; cast to float in setup())
+    long  minPos;
+    long  maxPos;
+    long  homingBackoffSteps;
+    int   maxSpeed;          // steps/s
+    int   accel;             // steps/s²
+    int   homingSpeed;       // steps/s
+  };
+
+  constexpr GaugeConfig gaugeConfigs[] = {
+    // dir  step  en   dirInv stepHi enLow  min   max   backoff  speed  accel  homeSpd
+    {  48,  49,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+    {   8,   9,  -1,  true,  true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+    {  52,  53,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+    {  50,  51,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+  };
+
+  static const uint8_t GAUGE_COUNT =
+      sizeof(gaugeConfigs) / sizeof(gaugeConfigs[0]);
+  ```
+
+  To add a fifth gauge later: append one row to `gaugeConfigs[]`. Nothing else changes.
+
+---
+
+## Task 2: Wire `gauge_config.h` into `Gaugecontroller.ino`
+
+**Files:**
+- Modify: `Gaugecontroller/Gaugecontroller.ino`
+
+This task makes six targeted edits in order. Each edit is shown as old → new. Do them top-to-bottom so line numbers don't shift unexpectedly.
+
+- [ ] **Step 1: Add the include**
+
+  After the existing three `#include` lines at the top, add:
+
+  ```cpp
+  #include "gauge_config.h"
+  ```
+
+  The top of the file should now read:
+
+  ```cpp
+  #include <Arduino.h>
+  #include <avr/interrupt.h>
+  #include <math.h>
+  #include "gauge_config.h"
+  ```
+
+- [ ] **Step 2: Remove `GAUGE_COUNT` and `GaugePins`**
+
+  Delete these two blocks entirely (they are now in `gauge_config.h`):
+
+  ```cpp
+  static const uint8_t GAUGE_COUNT = 4;
+  ```
+
+  ```cpp
+  struct GaugePins {
+    uint8_t dirPin;
+    uint8_t stepPin;
+    int8_t enablePin;          // -1 means there is no enable pin
+    bool dirInverted;
+    bool stepActiveHigh;
+    bool enableActiveLow;
+  };
+
+  constexpr GaugePins gaugePins[GAUGE_COUNT] = {
+    // dir, step, en, dirInv, stepHigh, enActiveLow
+    {48, 49, -1, false, true, true},   // Gauge 0
+    {8,  9,  -1, true,  true, true},   // Gauge 1
+    {52, 53, -1, false, true, true},   // Gauge 2
+    {50, 51, -1, false, true, true},   // Gauge 3
+  };
+  ```
+
+- [ ] **Step 3: Strip hardcoded defaults from `struct Gauge`**
+
+  In the `Gauge` struct definition, remove the numeric defaults from the six motion fields. Change:
+
+  ```cpp
+  long minPos = 0;
+  long maxPos = 3780;
+  long homingBackoffSteps = 3800; // Deliberately a touch past full reverse travel.
+
+  float velocity = 0.0f;
+  float maxSpeed = 4000.0f;
+  float accel = 6000.0f;
+  float homingSpeed = 500.0f;
+  ```
+
+  To:
+
+  ```cpp
+  long minPos = 0;
+  long maxPos = 0;
+  long homingBackoffSteps = 0;
+
+  float velocity = 0.0f;
+  float maxSpeed = 0.0f;
+  float accel = 0.0f;
+  float homingSpeed = 0.0f;
+  ```
+
+  These will be populated from `gaugeConfigs[i]` in `setup()` (Step 5).
+
+- [ ] **Step 4: Update `gaugePins` → `gaugeConfigs` references outside `setup()`**
+
+  Three functions reference `gaugePins`. Update each one:
+
+  **`writeDirectionPin` (~line 106):**
+  ```cpp
+  // Before
+  bool level = gaugePins[id].dirInverted ? !forward : forward;
+
+  // After
+  bool level = gaugeConfigs[id].dirInverted ? !forward : forward;
+  ```
+
+  **`writeStepPin` (~line 111):**
+  ```cpp
+  // Before
+  bool level = gaugePins[id].stepActiveHigh ? active : !active;
+
+  // After
+  bool level = gaugeConfigs[id].stepActiveHigh ? active : !active;
+  ```
+
+  **`configureStepperHardware` (~line 152):**
+  ```cpp
+  // Before
+  stepperHardware[id].stepPort = portOutputRegister(digitalPinToPort(gaugePins[id].stepPin));
+  stepperHardware[id].stepMask = digitalPinToBitMask(gaugePins[id].stepPin);
+  stepperHardware[id].dirPort  = portOutputRegister(digitalPinToPort(gaugePins[id].dirPin));
+  stepperHardware[id].dirMask  = digitalPinToBitMask(gaugePins[id].dirPin);
+
+  // After
+  stepperHardware[id].stepPort = portOutputRegister(digitalPinToPort(gaugeConfigs[id].stepPin));
+  stepperHardware[id].stepMask = digitalPinToBitMask(gaugeConfigs[id].stepPin);
+  stepperHardware[id].dirPort  = portOutputRegister(digitalPinToPort(gaugeConfigs[id].dirPin));
+  stepperHardware[id].dirMask  = digitalPinToBitMask(gaugeConfigs[id].dirPin);
+  ```
+
+  **`setEnable` (~line 291):**
+  ```cpp
+  // Before
+  int8_t pin = gaugePins[id].enablePin;
+  if (pin < 0) return;
+  bool level = gaugePins[id].enableActiveLow ? !en : en;
+
+  // After
+  int8_t pin = gaugeConfigs[id].enablePin;
+  if (pin < 0) return;
+  bool level = gaugeConfigs[id].enableActiveLow ? !en : en;
+  ```
+
+- [ ] **Step 5: Update `setup()` — pin references and add motion default init**
+
+  In `setup()`, the `for` loop currently reads:
+
+  ```cpp
+  for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
+    pinMode(gaugePins[i].dirPin, OUTPUT);
+    pinMode(gaugePins[i].stepPin, OUTPUT);
+    configureStepperHardware(i);
+
+    digitalWrite(gaugePins[i].dirPin, LOW);
+    digitalWrite(gaugePins[i].stepPin, gaugePins[i].stepActiveHigh ? LOW : HIGH);
+
+    if (gaugePins[i].enablePin >= 0) {
+      pinMode(gaugePins[i].enablePin, OUTPUT);
+      setEnable(i, true);
+    }
+
+    gauges[i].lastUpdateMicros = micros();
+  }
+  ```
+
+  Replace it with:
+
+  ```cpp
+  for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
+    pinMode(gaugeConfigs[i].dirPin, OUTPUT);
+    pinMode(gaugeConfigs[i].stepPin, OUTPUT);
+    configureStepperHardware(i);
+
+    digitalWrite(gaugeConfigs[i].dirPin, LOW);
+    digitalWrite(gaugeConfigs[i].stepPin, gaugeConfigs[i].stepActiveHigh ? LOW : HIGH);
+
+    if (gaugeConfigs[i].enablePin >= 0) {
+      pinMode(gaugeConfigs[i].enablePin, OUTPUT);
+      setEnable(i, true);
+    }
+
+    gauges[i].minPos             = gaugeConfigs[i].minPos;
+    gauges[i].maxPos             = gaugeConfigs[i].maxPos;
+    gauges[i].homingBackoffSteps = gaugeConfigs[i].homingBackoffSteps;
+    gauges[i].maxSpeed           = (float)gaugeConfigs[i].maxSpeed;
+    gauges[i].accel              = (float)gaugeConfigs[i].accel;
+    gauges[i].homingSpeed        = (float)gaugeConfigs[i].homingSpeed;
+
+    gauges[i].lastUpdateMicros = micros();
+  }
+  ```
+
+- [ ] **Step 6: Compile and verify clean**
+
+  ```bash
+  arduino-cli compile --fqbn arduino:avr:mega Gaugecontroller
+  ```
+
+  Expected: zero errors, zero warnings about `gaugePins` or `GAUGE_COUNT`. If the compiler reports "use of undeclared identifier 'gaugePins'", grep for any remaining reference:
+
+  ```bash
+  grep -n "gaugePins" Gaugecontroller/Gaugecontroller.ino
+  ```
+
+  Should return nothing.
+
+- [ ] **Step 7: Commit**
+
+  ```bash
+  git add Gaugecontroller/gauge_config.h Gaugecontroller/Gaugecontroller.ino
+  git commit -m "refactor: centralise gauge config in gauge_config.h"
+  ```
+
+---
+
+## Task 3: Rewrite `parseSpeed`, `parseAccel`, `parseSweep` to use `sscanf`
+
+**Files:**
+- Modify: `Gaugecontroller/Gaugecontroller.ino`
+
+- [ ] **Step 1: Replace `parseSpeed`**
+
+  Find and replace the entire `parseSpeed` function:
+
+  ```cpp
+  // Before (~15 lines)
+  bool parseSpeed(const String& line) {
+    int firstSpace = line.indexOf(' ');
+    int secondSpace = line.indexOf(' ', firstSpace + 1);
+    if (firstSpace < 0 || secondSpace < 0) return false;
+    if (line.substring(0, firstSpace) != "SPEED") return false;
+
+    int id = line.substring(firstSpace + 1, secondSpace).toInt();
+    float speed = line.substring(secondSpace + 1).toFloat();
+
+    if (id < 0 || id >= GAUGE_COUNT) {
+      sendReply("ERR BAD_ID");
+      return true;
+    }
+    if (speed <= 0.0f) {
+      sendReply("ERR BAD_SPEED");
+      return true;
+    }
+
+    gauges[id].maxSpeed = speed;
+    sendReply("OK");
+    return true;
+  }
+  ```
+
+  ```cpp
+  // After
+  bool parseSpeed(const String& line) {
+    int id; float speed;
+    if (sscanf(line.c_str(), "SPEED %d %f", &id, &speed) == 2) {
+      if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID");    return true; }
+      if (speed <= 0.0f)               { sendReply("ERR BAD_SPEED"); return true; }
+      gauges[id].maxSpeed = speed;
+      sendReply("OK");
+      return true;
+    }
+    return false;
+  }
+  ```
+
+- [ ] **Step 2: Replace `parseAccel`**
+
+  ```cpp
+  // Before (~15 lines)
+  bool parseAccel(const String& line) {
+    int firstSpace = line.indexOf(' ');
+    int secondSpace = line.indexOf(' ', firstSpace + 1);
+    if (firstSpace < 0 || secondSpace < 0) return false;
+    if (line.substring(0, firstSpace) != "ACCEL") return false;
+
+    int id = line.substring(firstSpace + 1, secondSpace).toInt();
+    float accel = line.substring(secondSpace + 1).toFloat();
+
+    if (id < 0 || id >= GAUGE_COUNT) {
+      sendReply("ERR BAD_ID");
+      return true;
+    }
+    if (accel <= 0.0f) {
+      sendReply("ERR BAD_ACCEL");
+      return true;
+    }
+
+    gauges[id].accel = accel;
+    sendReply("OK");
+    return true;
+  }
+  ```
+
+  ```cpp
+  // After
+  bool parseAccel(const String& line) {
+    int id; float accel;
+    if (sscanf(line.c_str(), "ACCEL %d %f", &id, &accel) == 2) {
+      if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID");    return true; }
+      if (accel <= 0.0f)               { sendReply("ERR BAD_ACCEL"); return true; }
+      gauges[id].accel = accel;
+      sendReply("OK");
+      return true;
+    }
+    return false;
+  }
+  ```
+
+- [ ] **Step 3: Replace `parseSweep`**
+
+  ```cpp
+  // Before (~20 lines)
+  bool parseSweep(const String& line) {
+    int firstSpace = line.indexOf(' ');
+    int secondSpace = line.indexOf(' ', firstSpace + 1);
+    int thirdSpace = line.indexOf(' ', secondSpace + 1);
+
+    if (firstSpace < 0 || secondSpace < 0 || thirdSpace < 0) return false;
+    if (line.substring(0, firstSpace) != "SWEEP") return false;
+
+    int id = line.substring(firstSpace + 1, secondSpace).toInt();
+    float accel = line.substring(secondSpace + 1, thirdSpace).toFloat();
+    float speed = line.substring(thirdSpace + 1).toFloat();
+
+    if (id < 0 || id >= GAUGE_COUNT) {
+      sendReply("ERR BAD_ID");
+      return true;
+    }
+
+    Gauge& g = gauges[id];
+
+    if (accel <= 0.0f || speed <= 0.0f) {
+      g.sweepEnabled = false;
+      g.velocity = 0.0f;
+      stopTimerStepping(id);
+      sendReply("OK");
+      return true;
+    }
+
+    g.accel = accel;
+    g.maxSpeed = speed;
+    g.sweepEnabled = true;
+    g.sweepTowardMax = true;
+    atomicWriteLong(g.targetPos, g.maxPos);
+    sendReply("OK");
+    return true;
+  }
+  ```
+
+  ```cpp
+  // After
+  bool parseSweep(const String& line) {
+    int id; float accel, speed;
+    if (sscanf(line.c_str(), "SWEEP %d %f %f", &id, &accel, &speed) == 3) {
+      if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID"); return true; }
+      Gauge& g = gauges[id];
+      if (accel <= 0.0f || speed <= 0.0f) {
+        g.sweepEnabled = false;
+        g.velocity = 0.0f;
+        stopTimerStepping(id);
+        sendReply("OK");
+        return true;
+      }
+      g.accel = accel;
+      g.maxSpeed = speed;
+      g.sweepEnabled = true;
+      g.sweepTowardMax = true;
+      atomicWriteLong(g.targetPos, g.maxPos);
+      sendReply("OK");
+      return true;
+    }
+    return false;
+  }
+  ```
+
+- [ ] **Step 4: Verify no `indexOf`/`substring` remain in any `parse*` function**
+
+  ```bash
+  grep -n "indexOf\|substring" Gaugecontroller/Gaugecontroller.ino
+  ```
+
+  Expected: no output. If any lines appear, check which function still uses the old pattern and redo that step.
+
+- [ ] **Step 5: Compile and verify clean**
+
+  ```bash
+  arduino-cli compile --fqbn arduino:avr:mega Gaugecontroller
+  ```
+
+  Expected: zero errors.
+
+- [ ] **Step 6: Commit**
+
+  ```bash
+  git add Gaugecontroller/Gaugecontroller.ino
+  git commit -m "refactor: uniform sscanf parsing in parseSpeed, parseAccel, parseSweep"
+  ```
+
+---
+
+## Optional hardware smoke-test (when board is available)
+
+After uploading, send these commands over serial and confirm expected replies:
+
+```
+PING          → PONG
+HOMEALL       → OK  (then each gauge homes; HOMED 0..3 appear on debug port)
+POS?          → POS 0 0 0 1 0 0  (×4, one per gauge)
+SET 0 1000    → OK
+SPEED 0 2000  → OK
+ACCEL 0 8000  → OK
+SWEEP 0 6000 4000 → OK
+SWEEP 0 0 0   → OK  (stops sweep)
+```
+
+No new error codes were introduced; all existing commands should behave identically to v1.

docs/superpowers/specs/2026-05-21-gaugecontroller-v2-design.md

@@ -0,0 +1,162 @@
+# Gaugecontroller v2.0 Design
+
+**Date:** 2026-05-21  
+**Branch:** Stepper-Only  
+**Scope:** Code quality / architecture — same features, better structure. No behaviour change.
+
+## Goal
+
+Eliminate scattered magic constants and inconsistent parsing patterns. A developer adding or tuning a gauge should only need to edit one file.
+
+## What is NOT changing
+
+- ISR logic, Q16 fixed-point stepping, trapezoidal velocity profile
+- Serial protocol commands and responses
+- Runtime `Gauge` struct fields (stay `float` for velocity, speed, accel)
+- LED code (absent on this branch; out of scope)
+
+---
+
+## Section 1: `gauge_config.h`
+
+Create `Gaugecontroller/gauge_config.h` alongside the sketch.
+
+### New struct
+
+```cpp
+struct GaugeConfig {
+  // Hardware
+  uint8_t dirPin;
+  uint8_t stepPin;
+  int8_t  enablePin;       // -1 = no enable pin
+  bool    dirInverted;
+  bool    stepActiveHigh;
+  bool    enableActiveLow;
+
+  // Motion defaults (integers — cast to float in setup())
+  long  minPos;
+  long  maxPos;
+  long  homingBackoffSteps;
+  int   maxSpeed;          // steps/s
+  int   accel;             // steps/s²
+  int   homingSpeed;       // steps/s
+};
+```
+
+### Config table
+
+```cpp
+constexpr GaugeConfig gaugeConfigs[] = {
+  // dir  step  en   dirInv stepHi enLow  min   max   backoff  speed  accel  homeSpd
+  {  48,  49,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+  {   8,   9,  -1,  true,  true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+  {  52,  53,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+  {  50,  51,  -1,  false, true,  true,    0,  3780,   3800,   4000,  6000,    500 },
+};
+
+static const uint8_t GAUGE_COUNT =
+    sizeof(gaugeConfigs) / sizeof(gaugeConfigs[0]);
+```
+
+Adding gauge 5 is one new table row. `GAUGE_COUNT` updates automatically.
+
+### Changes to `Gaugecontroller.ino`
+
+- Remove `constexpr GaugePins gaugePins[]`, `struct GaugePins`, and the hardcoded `GAUGE_COUNT`.
+- Add `#include "gauge_config.h"`.
+- In `setup()`, initialise each `Gauge`'s motion defaults from `gaugeConfigs[i]`:
+
+```cpp
+gauges[i].minPos             = gaugeConfigs[i].minPos;
+gauges[i].maxPos             = gaugeConfigs[i].maxPos;
+gauges[i].homingBackoffSteps = gaugeConfigs[i].homingBackoffSteps;
+gauges[i].maxSpeed           = (float)gaugeConfigs[i].maxSpeed;
+gauges[i].accel              = (float)gaugeConfigs[i].accel;
+gauges[i].homingSpeed        = (float)gaugeConfigs[i].homingSpeed;
+```
+
+- All existing references to `gaugePins[i].dirPin` etc. become `gaugeConfigs[i].dirPin` etc. (field names are identical).
+- Remove the hardcoded default initialisers from the `Gauge` struct definition (`maxPos = 3780`, `homingBackoffSteps = 3800`, `maxSpeed = 4000.0f`, `accel = 6000.0f`, `homingSpeed = 500.0f`, `minPos = 0`). These fields become zero-initialised and are then set from `gaugeConfigs[i]` in `setup()`, eliminating the risk of the struct defaults and config table silently diverging.
+
+---
+
+## Section 2: Uniform `sscanf` parsing
+
+Three `parse*` functions currently use manual `indexOf`/`substring`. Convert them to `sscanf` to match the rest of the parser.
+
+### `parseSpeed`
+
+```cpp
+bool parseSpeed(const String& line) {
+  int id; float speed;
+  if (sscanf(line.c_str(), "SPEED %d %f", &id, &speed) == 2) {
+    if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID");    return true; }
+    if (speed <= 0.0f)               { sendReply("ERR BAD_SPEED"); return true; }
+    gauges[id].maxSpeed = speed;
+    sendReply("OK");
+    return true;
+  }
+  return false;
+}
+```
+
+### `parseAccel`
+
+```cpp
+bool parseAccel(const String& line) {
+  int id; float accel;
+  if (sscanf(line.c_str(), "ACCEL %d %f", &id, &accel) == 2) {
+    if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID");    return true; }
+    if (accel <= 0.0f)               { sendReply("ERR BAD_ACCEL"); return true; }
+    gauges[id].accel = accel;
+    sendReply("OK");
+    return true;
+  }
+  return false;
+}
+```
+
+### `parseSweep`
+
+```cpp
+bool parseSweep(const String& line) {
+  int id; float accel, speed;
+  if (sscanf(line.c_str(), "SWEEP %d %f %f", &id, &accel, &speed) == 3) {
+    if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID"); return true; }
+    Gauge& g = gauges[id];
+    if (accel <= 0.0f || speed <= 0.0f) {
+      g.sweepEnabled = false;
+      g.velocity = 0.0f;
+      stopTimerStepping(id);
+      sendReply("OK");
+      return true;
+    }
+    g.accel        = accel;
+    g.maxSpeed     = speed;
+    g.sweepEnabled = true;
+    g.sweepTowardMax = true;
+    atomicWriteLong(g.targetPos, g.maxPos);
+    sendReply("OK");
+    return true;
+  }
+  return false;
+}
+```
+
+No change to accepted syntax, error codes, or response format.
+
+---
+
+## File inventory
+
+| File | Change |
+|---|---|
+| `Gaugecontroller/gauge_config.h` | New — all pin + motion defaults |
+| `Gaugecontroller/Gaugecontroller.ino` | Remove `GaugePins`, add include, update `setup()`, rewrite 3 parsers |
+
+## Success criteria
+
+- Sketch compiles cleanly with `arduino-cli compile --fqbn arduino:avr:mega Gaugecontroller`
+- `GAUGE_COUNT` need not be edited when adding a gauge — only `gaugeConfigs[]` changes
+- No `indexOf`/`substring` remain in any `parse*` function
+- All existing protocol commands behave identically to v1

wiring.md

@@ -163,19 +163,22 @@ Also connect:
 
 If your driver boards need separate motor power, supply that from the proper motor supply. Do not power motors from the Mega `5V` pin.
 
-## WS2812B LED Strip
+## WS2812 LED Strips
 
-The current sketch expects one shared WS2812B chain.
+The current sketch expects two LED data chains. Backlight and status LEDs stay
+on the main strip; the red/green dial indicator LEDs are on their own strip.
 
-| Mega Pin | WS2812B |
+| Mega Pin | LED Strip |
 |---|---|
-| `D22` | `DIN` |
+| `D22` | main backlight/status `DIN` |
-| `5V` | `5V` |
+| `D36` | indicator `DIN` |
-| `GND` | `GND` |
+| `5V` | both strips `5V` |
+| `GND` | both strips `GND` |
 
 Notes:
 
-- the code expects `7 LEDs per gauge`, so `21 LEDs total`
+- the command protocol still exposes `7 LEDs per gauge`
+- logical indices `0-2` are backlight, `3-4` are indicators, and `5-6` are status
 - use a proper 5V supply sized for the LED current
 - keep LED ground common with the Mega