# Python GPIO Development

This document describes the basic Python GPIO workflow on Quectel Pi M1/L1. 

## Environment Check

```bash
gpiodetect
ls -l /dev/gpiochip*
gpioinfo
python3 --version
```

| **Device Node** | **Description** |
| --- | --- |
| /dev/gpiochip0 | Currently verified as the main GPIO controller, label 400000.pinctrl |
| /dev/gpiochip1 | Currently verified as the PMIC-related GPIO controller |
| /dev/gpiochip2 | Currently verified as the LPI-related GPIO controller |

## Install Dependencies

```bash
sudo apt update
sudo apt install -y gpiod python3-venv python3-pip
python3 -m venv .venv
source .venv/bin/activate
pip install python-periphery
```

## Read Example

The example uses line 36 on `/dev/gpiochip0`. Confirm the actual physical pin mapping before wiring.

```python
from periphery import GPIO

chip = "/dev/gpiochip0"
line = 36

gpio = GPIO(chip, line, "in")
try:
    print(gpio.read())
finally:
    gpio.close()
```

## Output Example

```python
from periphery import GPIO
import time

chip = "/dev/gpiochip0"
line = 36

gpio = GPIO(chip, line, "out")
try:
    gpio.write(True)
    time.sleep(1)
    gpio.write(False)
finally:
    gpio.close()
```

## Notes

- GPIO line offset is not the same as the physical header pin number.

- Use `gpioinfo` first; do not take over lines marked with `[used]`.

- The checked board uses libgpiod v1.6.3 for command-line validation.