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overland-controller/docs/wiring.md
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# Wiring
This document describes the current planned wiring for the Overland Controller install.
The current system uses:
- ESP32 2-relay controller board
- Raspberry Pi Pico 2 W dashboard
- CAT5/CAT6 cable between rear controller and dash
- 12V-to-5V buck converter in the dash enclosure
- DS18B20 temperature sensors
- JBD/Xiaoxiang BMS over BLE
- External automotive relays for high-current loads
---
## Current ESP32 Relay Board
Board markings:
ESP32_Relay_X2
Relay contact terminals:
NO1 COM1 NC1 NO2 COM2 NC2
Power terminal:
VCC GND 5V
UART/programming header:
IO0 GND GND RX TX 5V
Firmware relay mapping:
relay_1 = GPIO16
relay_2 = GPIO17
---
## System Power Overview
Plain text diagram:
House Battery +
|
+---- Main fuse / distribution
|
+---- 2A fuse --------------------> ESP32 relay board VCC
|
+---- 1A or 2A fuse --------------> CAT5 blue pair to dash +12V
|
+---- Load fuse ------------------> Automotive relay #1 pin 30
|
+---- Load fuse ------------------> Automotive relay #2 pin 30
House Battery -
|
+---------------------------------> Common ground bus
|
+--> ESP32 relay board GND
+--> CAT5 green pair to dash GND
+--> Automotive relay coil grounds
+--> Load grounds
Notes:
- Fuse every positive feed.
- Keep all grounds common.
- Do not run high-current loads directly through the ESP32 relay board.
- Use the ESP32 relay board to trigger automotive relays.
---
## ESP32 Board Power
Use the bottom-right power terminal:
VCC GND 5V
Recommended wiring:
House battery +
|
+-- 2A fuse
|
+---> ESP32 VCC
House battery -
|
+---> ESP32 GND
Leave the ESP32 board 5V terminal unused unless verified for your exact board/power setup.
---
## Pico Dashboard Power Over CAT5
The dash Pico should be powered from a buck converter inside the dash enclosure.
Rear compartment:
House battery +
|
+-- 1A or 2A fuse
|
+---> CAT5 blue/white + blue conductors
House battery -
|
+---> CAT5 green/white + green conductors
Dash enclosure:
CAT5 blue pair +12V
|
+---> Buck converter IN+
CAT5 green pair GND
|
+---> Buck converter IN-
Buck converter OUT+ 5V
|
+---> Pico VSYS
Buck converter OUT- GND
|
+---> Pico GND
Important:
- Do not connect 5V to Pico 3V3.
- Use Pico VSYS for 5V input.
- Keep ESP32 GND and Pico GND connected through the CAT5 ground pair.
---
## CAT5 / CAT6 Cable Plan
Recommended CAT5/CAT6 wiring between the rear ESP32 controller and dash Pico:
Orange/White ESP32 TX ---> Pico GP1 RX
Orange ESP32 RX <--- Pico GP0 TX
Green/White Ground
Green Ground
Blue/White +12V fused dash feed
Blue +12V fused dash feed
Brown/White Spare
Brown Spare
Notes:
- Use two conductors for +12V.
- Use two conductors for ground.
- UART requires shared ground.
- Brown pair is reserved for future expansion.
---
## Pico 2 W UART Pins
Recommended Pico UART pins:
Pico GP0 = UART0 TX
Pico GP1 = UART0 RX
Connection:
ESP32 TX ---> Pico GP1 RX
ESP32 RX <--- Pico GP0 TX
ESP32 GND ---> Pico GND
Do not connect ESP32 5V to Pico unless intentionally using it as a power source.
Current plan is to power Pico from local dash buck converter instead.
---
## ESP32 UART Header
The ESP32 relay board exposes a 6-pin header:
IO0 GND GND RX TX 5V
Use:
TX ---> Pico GP1 RX
RX <--- Pico GP0 TX
GND ---> Pico GND
Do not use IO0 for dashboard wiring.
Do not use 5V for dashboard power in the current design.
---
## DS18B20 Temperature Sensor Bus
Recommended ESP32 GPIO:
GPIO4
All DS18B20 sensors share one 1-Wire data bus.
Plain text diagram:
ESP32 3.3V
|
+---- 4.7k pull-up resistor
|
ESP32 GPIO4 --------------------+---- DS18B20 Sensor 1 data
|
+---- DS18B20 Sensor 2 data
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+---- DS18B20 Sensor 3 data
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+---- DS18B20 Sensor 4 data
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+---- Additional sensors up to temp_8
ESP32 3.3V -------------------------- DS18B20 red wires
ESP32 GND -------------------------- DS18B20 black wires
ESP32 GPIO4 ------------------------- DS18B20 data wires
Typical waterproof DS18B20 wiring:
Red = 3.3V
Black = GND
Yellow = Data
Important:
- A 4.7k resistor is required between 3.3V and data.
- One pull-up resistor is used for the whole bus.
- Do not use one resistor per sensor.
- Long leads may need clean splices and good grounding.
---
## BMS Connection
The JBD/Xiaoxiang BMS is wireless.
Connection:
ESP32 <---- BLE ----> JBD/Xiaoxiang BMS
No physical BMS data wiring is currently required.
The BMS Bluetooth address is stored in controller configuration.
---
## Relay Control Strategy
The onboard ESP32 relays should trigger automotive relays.
They should not directly power large vehicle loads.
Recommended pattern:
ESP32 onboard relay
|
+-- switches automotive relay coil
|
+-- automotive relay switches load power
This keeps high current off the ESP32 board.
---
## Relay 1 Automotive Relay Wiring
Example installation-specific name:
relay_1 = Starlink
ESP32 board contact terminals:
COM1
NO1
Automotive relay wiring:
House battery +
|
+-- load fuse
|
+---> Automotive relay pin 30
Automotive relay pin 87
|
+---> Load positive
Load negative
|
+---> Ground bus
Automotive relay pin 85
|
+---> Ground bus
Automotive relay pin 86
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+---> Switched positive from ESP32 relay COM1/NO1 circuit
ESP32 relay contact wiring concept:
Fused low-current +12V
|
+---> ESP32 relay COM1
ESP32 relay NO1
|
+---> Automotive relay pin 86
When relay_1 turns on, COM1 connects to NO1 and energizes the automotive relay coil.
---
## Relay 2 Automotive Relay Wiring
Example installation-specific name:
relay_2 = Fridge
ESP32 board contact terminals:
COM2
NO2
Automotive relay wiring:
House battery +
|
+-- load fuse
|
+---> Automotive relay pin 30
Automotive relay pin 87
|
+---> Load positive
Load negative
|
+---> Ground bus
Automotive relay pin 85
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+---> Ground bus
Automotive relay pin 86
|
+---> Switched positive from ESP32 relay COM2/NO2 circuit
ESP32 relay contact wiring concept:
Fused low-current +12V
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+---> ESP32 relay COM2
ESP32 relay NO2
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+---> Automotive relay pin 86
When relay_2 turns on, COM2 connects to NO2 and energizes the automotive relay coil.
---
## Automotive Relay Pin Reference
Common Bosch-style relay pins:
30 = Common load power input
87 = Normally open load output
87a = Normally closed output, if present
85 = Coil side
86 = Coil side
Recommended use:
30 = fused battery positive
87 = load positive
85 = ground
86 = switched positive from ESP32 relay board
---
## Future Reserved Inputs
Do not wire these yet unless firmware support has been added.
Recommended reservations:
GPIO34 = Ignition sense input
GPIO35 = House battery voltage sense input
Reason:
- GPIO34 and GPIO35 are input-only.
- Input-only pins are appropriate for sensing.
- They are not appropriate for relay outputs.
Important:
Never connect vehicle 12V directly to an ESP32 GPIO.
Use a voltage divider or proper interface circuit.
---
## Current Version 1 Wiring Summary
Current required physical wiring:
ESP32 board VCC/GND from fused house battery power
ESP32 TX/RX/GND to Pico over CAT5
12V fused dash feed and ground to Pico dash enclosure over CAT5
Dash buck converter 12V to 5V
Buck 5V to Pico VSYS
ESP32 GPIO4 to DS18B20 1-Wire bus
4.7k pull-up from GPIO4 data bus to 3.3V
ESP32 relay COM/NO contacts to automotive relay coils
Automotive relays to actual high-current loads
ESP32 BLE to JBD/Xiaoxiang BMS
---
## Safety Notes
- Fuse every positive feed.
- Use proper wire gauge for each load.
- Keep high-current wiring separate from signal wiring where possible.
- Use common ground between ESP32, Pico, buck converter, relays, sensors, and battery.
- Do not connect 12V directly to any ESP32 or Pico GPIO.
- Do not power high-current loads directly through the ESP32 relay board.
- Test relay behavior with a multimeter before connecting expensive loads.
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