EV OBD Feeder for aa-proxy-rs

This Go application reads battery data from an electric vehicle via OBD-II and sends it to aa-proxy-rs for Android Auto integration.

Features

• Reads battery state of charge (SoC %), available energy (Wh), and external temperature
• USB connection to OBDLink EX adapter (no Bluetooth support, other USB ELM327 may work but untested)
• Configurable polling interval (default: 5 seconds)
• Support for multiple vehicle configurations via YAML files
• Mock mode for testing without vehicle connection
• Automatic retry and caching of last known good values

Building

For Radxa Zero 3W (ARM64 Linux)

GOOS=linux GOARCH=arm64 go build -o ev-obd-feeder

Deployment to Radxa (aa-proxy-rs buildroot image)

1. Build for ARM64:

GOOS=linux GOARCH=arm64 go build -o ev-obd-feeder

2. Copy the binary, config, and init script to the Radxa:

scp -O ev-obd-feeder root@10.0.0.1:/usr/bin/
scp -O configs/ioniq5n.yaml root@10.0.0.1:/etc/ev-obd-feeder.yaml
scp -O init.d/S99ev-obd-feeder root@10.0.0.1:/etc/init.d/

3. SSH into the Radxa:

ssh root@10.0.0.1

4. Verify the OBDLink EX USB connection:

# The OBDLink EX appears as /dev/ttyUSB0 when connected via USB
ls -la /dev/ttyUSB0

# The config should already have the correct path (/dev/ttyUSB0)
# Edit only if needed:
vi /etc/ev-obd-feeder.yaml

5. Make the files executable and start the service:

chmod +x /usr/bin/ev-obd-feeder
chmod +x /etc/init.d/S99ev-obd-feeder
/etc/init.d/S99ev-obd-feeder start

Usage

Manual operation (for testing)

# Normal mode
/usr/bin/ev-obd-feeder -config /etc/ev-obd-feeder.yaml

# Debug mode (verbose logging)
/usr/bin/ev-obd-feeder -config /etc/ev-obd-feeder.yaml -debug

# Test mode (mock data, no vehicle needed)
/usr/bin/ev-obd-feeder -config /etc/ev-obd-feeder.yaml -test -debug

Service control

# Start service
/etc/init.d/S99ev-obd-feeder start

# Stop service
/etc/init.d/S99ev-obd-feeder stop

# Restart service
/etc/init.d/S99ev-obd-feeder restart

# Check if running
/etc/init.d/S99ev-obd-feeder status

View logs

# Tail default log location
tail -f /var/log/ev-obd-feeder.log

Configuration

The application uses YAML configuration files. See configs/ioniq5n.yaml for an example.

Key configuration sections:

• serial: OBD adapter settings (device path and baud rate)
• vehicle: Vehicle name, battery capacity, and PID mappings
• aaproxy: URL for aa-proxy-rs battery endpoint (http://localhost:80/battery)
• poll_interval: How often to query the vehicle (default: 5s)

Vehicle Support

Currently configured for:

• Hyundai Ioniq 5 N (configs/ioniq5n.yaml)

The PID configuration is flexible and can be adapted for other vehicles by creating new YAML config files, should work seamlessly with other EGMP vehicles, anything else is untested.

Troubleshooting

1. No data from ECU: Ensure vehicle is ON or in accessory mode

2. Connection failed: Check OBDLink EX USB connection:

   # Verify USB device exists:
   ls -la /dev/ttyUSB0
   
   # Check if device is detected in kernel:
   dmesg | grep -i 'usb\|serial' | tail -10
   
   # Ensure OBDLink EX is powered on and connected via USB cable

3. aa-proxy connection failed: Verify aa-proxy-rs is running:

   ps aux | grep aa-proxy-rs
   # Should see: /usr/bin/aa-proxy-rs
   
   # Check if listening on port 80:
   netstat -an | grep :80
   
   # Check aa-proxy-rs service:
   /etc/init.d/S93aa-proxy-rs status

Data Format

The application sends JSON data to aa-proxy-rs in this format:

{
  "battery_level_percentage": 67.5,
  "battery_level_wh": 54000,
  "battery_capacity_wh": 80000,
  "external_temp_celsius": 22.0
}

FAQ

1. Was this vibe coded?: Yes, most of the OBD scraping and parsing of the vendor specific Hyundai Mode 22 OBD codes were vibe coded. As is the debug function.
2. What is this purpose of this?: This was created as I wanted a seamless destination route planning inside Google Maps for use with my current car, aa-proxy-rs provided that and also had the added benefit of moving wireless AA to 5GHz for less interference. Hopefully this is useful for you as well.
3. How much RAM does this use?: This should use around 250MB RAM, so make sure your SBC has enough RAM.