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arduino_gauge_controller/Rewire_checklist.md
Adrian A. Baumann 8bdae1da9b Update docs and firmware for ESPHome bridge migration 
- Replace gauge.py (MicroPython) references with gaugecontroller.yaml (ESPHome)
- Update CLAUDE.md and README.md to document ESPHome-native API integration
- Update LED wiring docs for separate main/indicator strips (D22/D36)
- Refactor Arduino firmware to drive two WS2812 strips independently
- Add per-gauge physical offset caching for main and indicator LEDs
- Frame-limit breathe effect (16ms) to reduce unnecessary strip refreshes
2026-04-29 19:03:22 +02:00

7.1 KiB
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Rewire Checklist

This is a practical rebuild checklist for the current integrated setup:

  • Arduino Mega 2560
  • ESP32 running gauge.py
  • HV5812P
  • 4-digit VFD with decimal point and alarm bell
  • 3 gauge drivers
  • WS2812B LED chain

Use this to rebuild the bench wiring from scratch.

1. Power Off Everything

  • disconnect all power supplies
  • disconnect USB power if it is currently feeding any board
  • do not move wires while the VFD high-voltage supply is live

2. Place The Main Parts

  • place the Arduino Mega 2560
  • place the ESP32
  • place the HV5812P
  • place the 3 gauge driver boards
  • place the WS2812B strip connection point
  • place the VFD tube connection point

3. Establish A Common Ground First

Before anything else, create one common logic ground network.

Connect:

  • Mega GND -> ground rail
  • ESP32 GND -> same ground rail
  • HV5812P GND -> same ground rail
  • Gauge driver 0 logic GND -> same ground rail
  • Gauge driver 1 logic GND -> same ground rail
  • Gauge driver 2 logic GND -> same ground rail
  • WS2812B GND -> same ground rail

If your VFD high-voltage supply has a ground/reference return:

  • VFD HV supply return -> same common ground rail

Do not continue until this common ground is in place.

4. Wire The Arduino Mega Power

Connect:

  • regulated 5V logic supply -> Mega 5V
  • ground rail -> Mega GND

Do not use the Mega to power motors.

5. Wire The ESP32 Power

Power the ESP32 in the way your board expects.

Typical options:

  • via board USB
  • via board 5V/VIN if your ESP32 board has its own regulator
  • via regulated 3.3V if it is a bare module that requires that

Also connect:

  • ESP32 GND -> common ground rail

Do not feed raw 5V into a bare 3.3V-only ESP32 module.

6. Wire The ESP32 UART To The Mega

Connect:

  • ESP32 GPIO17 (TX) -> Mega pin 19 (RX1)
  • ESP32 GPIO16 (RX) <- Mega pin 18 (TX1)
  • ESP32 GND -> Mega GND

This UART link is used by gauge.py.

7. Wire The HV5812P Logic Side

Connect:

  • Mega D46 -> HV5812P DATA IN / DIN
  • Mega D47 -> HV5812P CLOCK / CLK
  • Mega D48 -> HV5812P STROBE / LATCH
  • Mega D49 -> HV5812P BLANKING / OE
  • Mega 5V -> HV5812P VDD
  • Mega GND -> HV5812P GND

Do not connect:

  • Mega 5V -> HV5812P VPP

8. Wire The HV5812P High-Voltage Side

Connect:

  • VFD high-voltage positive supply -> HV5812P VPP
  • VFD high-voltage supply return / reference -> common ground rail

At this stage:

  • VDD must be 5V
  • VPP must be your VFD high-voltage rail

9. Wire The HV5812P Outputs To The VFD

Connect these one by one:

  • HVOut1 -> VFD segment A
  • HVOut2 -> VFD segment B
  • HVOut3 -> VFD segment C
  • HVOut4 -> VFD segment D
  • HVOut5 -> VFD segment E
  • HVOut6 -> VFD segment F
  • HVOut7 -> VFD segment G
  • HVOut8 -> VFD decimal point segment
  • HVOut9 -> VFD alarm bell segment
  • HVOut10 -> VFD digit 1 grid
  • HVOut11 -> VFD digit 2 grid
  • HVOut12 -> VFD digit 3 grid
  • HVOut13 -> VFD digit 4 grid
  • HVOut14 -> VFD indicator grid between digits 2 and 3

10. Wire The VFD Filament

Wire the VFD filament/heater exactly as required by your tube.

This checklist cannot specify the exact filament supply because it depends on the actual tube.

Required reminder:

  • do not power the filament from an Arduino GPIO
  • use the correct filament supply for the tube

11. Wire Gauge Driver 0

Connect:

  • Mega D50 -> Gauge driver 0 DIR
  • Mega D51 -> Gauge driver 0 STEP
  • Mega GND -> Gauge driver 0 logic GND

Then connect the motor side of that driver to:

  • its motor power supply
  • its gauge motor

according to the driver board you are using.

12. Wire Gauge Driver 1

Connect:

  • Mega D8 -> Gauge driver 1 DIR
  • Mega D9 -> Gauge driver 1 STEP
  • Mega GND -> Gauge driver 1 logic GND

Then connect the motor side of that driver to:

  • its motor power supply
  • its gauge motor

according to the driver board you are using.

13. Wire Gauge Driver 2

Connect:

  • Mega D52 -> Gauge driver 2 DIR
  • Mega D53 -> Gauge driver 2 STEP
  • Mega GND -> Gauge driver 2 logic GND

Then connect the motor side of that driver to:

  • its motor power supply
  • its gauge motor

according to the driver board you are using.

14. Wire The WS2812 LEDs

Connect:

  • Mega D22 -> main backlight/status strip DIN
  • Mega D36 -> indicator strip DIN
  • 5V LED supply -> both strip 5V inputs
  • both strip GND inputs -> common ground rail

If the LED chain is long or bright:

  • do not power it from the Mega 5V
  • use a proper external 5V supply

15. Verify The Pins That Changed For The Integrated VFD

The VFD is no longer on the old standalone pins.

Old standalone pins:

  • D51 -> DATA
  • D52 -> CLOCK
  • D53 -> STROBE
  • D49 -> BLANK

Current integrated pins:

  • D46 -> DATA
  • D47 -> CLOCK
  • D48 -> STROBE
  • D49 -> BLANK

So make sure:

  • nothing VFD-related is still on D51
  • nothing VFD-related is still on D52
  • nothing VFD-related is still on D53
  • only BLANK/OE remains on D49

16. Sanity Check Before Powering Logic

Check each item physically:

  • Mega D46 really goes to HV5812 DATA
  • Mega D47 really goes to HV5812 CLOCK
  • Mega D48 really goes to HV5812 STROBE
  • Mega D49 really goes to HV5812 BLANKING
  • Mega D50/D51 only go to gauge driver 0
  • Mega D8/D9 only go to gauge driver 1
  • Mega D52/D53 only go to gauge driver 2
  • Mega D22 only goes to WS2812B DIN
  • ESP32 GPIO17 goes to Mega RX1
  • ESP32 GPIO16 goes to Mega TX1
  • all grounds are common
  • HV5812 VDD is 5V
  • HV5812 VPP is high voltage, not 5V

17. Power Logic Only First

Apply only logic power first:

  • Mega power
  • ESP32 power
  • HV5812 VDD
  • WS2812 5V

Leave motor supply and VFD high voltage off for the first check if possible.

Verify:

  • Mega boots
  • ESP32 boots
  • UART communication works

18. Power The VFD High Voltage

Now apply the VFD high-voltage supply to HV5812 VPP.

Verify:

  • VDD remains 5V
  • VPP is the expected high voltage
  • no logic wire is heating

19. Power The Gauge Drivers

Now apply motor power to the gauge drivers.

Verify:

  • no driver fault LEDs
  • no motor heating or runaway movement immediately on power-up

20. First Functional Test

Test in this order:

  1. confirm the ESP32 can talk to the Mega
  2. send VFD 8888
  3. send VFD DEAD.!
  4. test one gauge movement from Home Assistant or MQTT
  5. test one LED output

21. If Something Is Wrong

Use this triage order:

  1. check grounds
  2. check VDD and VPP
  3. check Mega pin number mistakes
  4. check crossed UART lines
  5. check that the VFD is still on 46/47/48/49, not 51/52/53/49

22. Quick Reference

Mega pins in use

  • D8 -> gauge 1 DIR
  • D9 -> gauge 1 STEP
  • D22 -> WS2812 DIN
  • D46 -> HV5812 DATA
  • D47 -> HV5812 CLOCK
  • D48 -> HV5812 STROBE
  • D49 -> HV5812 BLANKING
  • D50 -> gauge 0 DIR
  • D51 -> gauge 0 STEP
  • D52 -> gauge 2 DIR
  • D53 -> gauge 2 STEP
  • D18 -> UART TX1 to ESP32 RX
  • D19 -> UART RX1 from ESP32 TX

VFD outputs

  • HVOut1..7 -> A..G
  • HVOut8 -> decimal point
  • HVOut9 -> alarm bell
  • HVOut10..13 -> digit grids 1..4
  • HVOut14 -> indicator grid
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