# ha-gpu-ccd - Home Assistant GPU CCD Temperature Monitor

A tool that retrieves GPU temperature information from Home Assistant MQTT and writes it to sysfs format files.

## Features

- Listen to Home Assistant MQTT temperature topics (supports multiple subscription modes)
- Convert temperature from Celsius to millidegrees (e.g., 80.5°C -> 80500)
- Write temperature to `/tmp/temp_{DEVICEID}` files (sysfs format)
- Support for monitoring specific devices or all devices

## Build

```bash
go build
```

## Usage

```bash
./ha-gpu-ccd --mqtt-host <MQTT_BROKER> --mqtt-port <PORT> --mqtt-username <USERNAME> --mqtt-password <PASSWORD>
```

### Parameters

- `--mqtt-host`: MQTT broker host (default: localhost)
- `--mqtt-port`: MQTT broker port (default: 1883)
- `--mqtt-username`: MQTT username (optional)
- `--mqtt-password`: MQTT password (optional)
- `--temp-dir`: Directory to write temperature files (default: /tmp)
- `--device-id`: Specific GPU device ID to monitor (leave empty to monitor all devices)

### Examples

```bash
# Connect to local MQTT broker, monitor all GPUs
./ha-gpu-ccd

# Connect to remote MQTT broker with authentication
./ha-gpu-ccd --mqtt-host 192.168.1.100 --mqtt-username homeassistant --mqtt-password mypassword

# Monitor only specific GPU device
./ha-gpu-ccd --device-id 00_04_00_0

# Custom temperature file directory
./ha-gpu-ccd --temp-dir /var/lib/gpu-temps

# Combined usage: specific device with authentication
./ha-gpu-ccd --mqtt-host 192.168.1.100 --mqtt-username user --mqtt-password pass --device-id 00_04_00_0
```

## Output Format

The tool creates a temperature file for each GPU device:
- File name: `temp_{DEVICEID}`
- Content: Temperature value in millidegrees (integer)
- Location: Default in `/tmp/` directory

Example:
- GPU device ID: `00_04_00_0`
- Temperature: 80.5°C
- File: `/tmp/temp_00_04_00_0`
- Content: `80500`

## MQTT Topic Format

The tool supports two subscription modes:

### Monitor All Devices (Default Mode)
Subscribe topic: `homeassistant/sensor/nvml-gpu/#`
Filter condition: Only process messages containing `_temperature/state`

### Monitor Specific Device
Subscribe topic: `homeassistant/sensor/nvml-gpu/{DEVICEID}_temperature/state`

Temperature topic format:
```
homeassistant/sensor/nvml-gpu/{DEVICEID}_temperature/state
```

Where `{DEVICEID}` is the device ID generated by the nvml-gpu-ha main program, e.g., `00_04_00_0`

## Logging

The tool outputs the following log messages:
- Connection status
- Subscription status
- Received temperature data
- File write status
- Error messages

## Troubleshooting

1. **Connection Failed**: Check if MQTT broker address and port are correct
2. **Authentication Failed**: Verify username and password are correct
3. **Subscription Failed**: Ensure MQTT broker supports wildcard subscriptions
4. **No Data Received**: Check if nvml-gpu-ha main program is running and sending data

## Integration

This tool is designed for integration with other systems, such as:
- System monitoring software
- Temperature control systems
- Automation scripts

By reading the `/tmp/temp_{DEVICEID}` files, other programs can obtain real-time GPU temperature information.