# Voron filament dryer

Arduino Nano firmware for a chamber dryer with four SHT31 humidity/temperature sensors, PID heater control, and PWM fan mixing.

## Pinout (Arduino Nano)

All settings below are defined in `include/config.h`.

| Signal | Nano pin | Notes |
|--------|----------|-------|
| I2C SDA | A4 | Shared bus (Wire) |
| I2C SCL | A5 | Shared bus (Wire) |
| TCA9548A mux | I2C `0x70` | 8-channel I2C multiplexer |
| SHT31 sensors | Mux channels 2, 3, 4, 5 | One sensor per channel |
| SHT31 address | `0x44` | ADDR pin low; use `0x45` if ADDR is high |
| Fan | D5 | 24 V fan via N-channel MOSFET (hardware PWM) |
| Heater | A2 | Solid-state relay (burst control) |

USB serial: **115200 baud**.

## Dev setup

### PlatformIO

This repo uses the PlatformIO CLI (see `.vscode/tasks.json`). If PlatformIO is already installed under `~/.platformio/penv/`, use that directly — you do not need to run the web installer again.

```bash
~/.platformio/penv/bin/pio --version
~/.platformio/penv/bin/pio run              # build
~/.platformio/penv/bin/pio run -t upload    # flash
~/.platformio/penv/bin/pio device monitor   # serial monitor
```

On Arch Linux / CachyOS, install via the package manager if you prefer:

```bash
sudo pacman -S platformio
```

If upload cannot find the port, add to `platformio.ini`:

```ini
upload_port = /dev/ttyUSB0    ; or /dev/ttyACM0, or a /dev/serial/by-id/... path
monitor_port = /dev/ttyUSB0
```

List available ports:

```bash
ls -la /dev/serial/by-id/
```

### Serial port permissions (Linux)

| Distribution | Group for serial access |
|--------------|-------------------------|
| Debian, Ubuntu, Raspberry Pi OS | `dialout` |
| Arch Linux, CachyOS | `uucp` |

```bash
# Debian / Ubuntu / Pi
sudo usermod -aG dialout $USER

# Arch / CachyOS
sudo usermod -aG uucp $USER
```

Log out and back in after adding your user to the group.

## First run

1. Flash firmware and open the serial monitor at 115200 baud.
2. Confirm `TCA9548A detected` and four valid sensor channels (`ch2`–`ch5`).
3. Run PID autotune once per physical unit (values are stored in EEPROM):

   ```
   target 0
   autotune 45
   ```

4. Start drying:

   ```
   target 55
   ```

Send `help` over serial for all commands (`target`, `fan on/off`, `log on/off`, `status`, `pid`, etc.).

## Raspberry Pi logging

Optional CSV capture over USB is documented in [pi-instructions.md](pi-instructions.md).