gpiochip2 0.9.3

Pythonic API for Linux's gpiochip chardev ABI v2.

Contents

• Features

• Requirements

• Examples

Pythonic API for Linux’s gpiochip chardev ABI v2.

Features

• Manage multiple GPIO lines at the same time, with bit operation affecting the entire line group at once (|=, &=, ^=).

• Get file event notification of timestamped line events (rising edge, falling edge).

• Get file event notifications (select, poll, epoll…) of gpiochip-level and line-level events.

• Control line parameters (pull-up, pull-down, active-low, debouncing, …).

• Pure python module: no compilation needed, not limited to CPython.

Requirements

• Linux >=5.10.0 for GPIO chardev ABI v2

• python stdlib >=3.7.10 (not tested with earlier versions, they may work)

Examples

Warning: this example is not meant to be executed as-is. Depending on what is connected to the GPIO lines used here (which is entirely board-dependent), this could cause all sort of problems, including permanent hardware damage.

This is only to be taken as a quick overview of this module’s API.

from gpiochip2 import GPIOChip, GPIO_V2_LINE_FLAG, EXPECT_PRECONFIGURED
with GPIOChip('/dev/gpiochip0', 'w+b') as gpiochip:
    # Get information about the gpio chip itself
    gpiochip.getInfo()
    # Get information about line 20
    gpiochip.getLineInfo(20)
    with gpiochip.openLines(
        line_list=[20, 21, 26],
        flags=GPIO_V2_LINE_FLAG.OUTPUT,
        consumer='sample-name'.encode('ascii'),
        flags_dict={
            # Line 26 is an input and produces event on falling edges
            2: GPIO_V2_LINE_FLAG.INPUT | GPIO_V2_LINE_FLAG.EDGE_FALLING,
        },
        default_dict={
            # Drive line 20 low immediately on opening
            0: False,
        },
        # Expect the GPIO lines to be correctly preconfigured (ex: by board-
        # specific firmware or devicetree).
        expect_preconfigured=EXPECT_PRECONFIGURED.DIRECTION,
        expect_preconfigured_dict={
            # Expect line 26 to have its edge detection preconfigured
            # in addition to its direction
            2: EXPECT_PRECONFIGURED.DIRECTION | EXPECT_PRECONFIGURED.EDGE,
        },
    ) as gpio_lines:
        # Read lines state
        value = gpio_lines.value
        # Change lines state
        gpio_lines.value = 0b11
        # Set line 21
        gpio_lines |= 2 # 1 << 1
        # Clear line 20
        gpio_lines &= 1 # 1 << 0
        # Read event
        lines.getEvent()

Notes on bit operations:

gpio_lines.lines |= some_mask will read then write the GPIO, while gpio_lines |= some_mask only needs to write, making it more efficient.

The same applies to &=, but not to other operators.

See also the examples directory for more realistic code.