# GPIO Via Golang

Ok, we are going to try the golang periph library with this.

## Permissions

The user running this binary must have `gpio` permissions on the Raspberry Pi.


Check if you can read the device without being root

```bash
head -c 1 /dev/gpiomem > /dev/null && echo "Success" || echo "Access Denied"
```

If you get access denied then we can create a gpio user group with udev runs that grant permissions to the /dev/gpiomem device.

```bash
sudo groupadd gpio
sudo usermod -aG gpio $USER
```

Create a udev rules file
```bash
sudo vim /etc/udev/rules.d/99-gpio.rules
```

Include the following:
```txt
# Access to the memory-mapped GPIO
SUBSYSTEM=="bcm2835-gpiomem", KERNEL=="gpiomem", GROUP="gpio", MODE="0660"

# Access to the gpiochip character devices (periph.io uses these)
SUBSYSTEM=="gpio", KERNEL=="gpiochip*", GROUP="gpio", MODE="0660"
```


```bash
sudo udevadm control --reload-rules && sudo udevadm trigger
```


## Periph Library

The Periph library is broken up into a number of sub libraries that are imported as needed. This allows the developers to decouple board implementations from drivers and devices.


```bash
go get periph.io/x/host/v3
go get periph.io/x/conn/v3
```