Tutorial — GPIO with libgpiod¶

libgpiod 2.x with the cdev-v2 ABI is the supported Linux API for GPIO. The old /sys/class/gpio sysfs interface is deprecated and RPBridge does not provide it.

Find the GPIO chip¶

gpiodetect
# gpiochip0  [rpbridge-gpio]  (14 lines)

Store the name in a variable for the rest of the examples:

CHIP=$(gpiodetect | awk '/rpbridge-gpio/ {print $1}')

Inspect lines¶

gpioinfo "$CHIP"
# gpiochip0 - 14 lines:
#     line  0:  unnamed  input  active-high
#     line  1:  unnamed  input  active-high
#     ...
#     line  7:  unnamed  input  active-high

Drive an output¶

gpioset --chip "$CHIP" 30=1
sleep 0.2
gpioset --chip "$CHIP" 30=0

Read an input¶

gpioget --chip "$CHIP" 7
# 1

Wait for an edge¶

gpiomon --chip "$CHIP" --rising-edge --falling-edge 7
# event:  FALLING EDGE offset: 7 timestamp: [1745324923.812 341 000]
# event:  RISING  EDGE offset: 7 timestamp: [1745324924.019 002 000]

Timestamps come from the firmware's device-boot clock, mapped onto CLOCK_MONOTONIC_RAW by the driver via the RPBP TIME_SYNC path. Accuracy is ±200 µs on a warm USB link.

Bias and drive configuration¶

gpioset --chip "$CHIP" --bias=pull-up --drive=open-source 30=1

All RP2350 pad features (pull up/down, open-drain, slew rate, drive strength) are mapped to the generic gpiod_line_request_config_flags.