GPIO

Code Example

from periphery import GPIO

# Open GPIO /dev/gpiochip0 line 10 with input direction
gpio_in = GPIO("/dev/gpiochip0", 10, "in")
# Open GPIO /dev/gpiochip0 line 12 with output direction
gpio_out = GPIO("/dev/gpiochip0", 12, "out")

value = gpio_in.read()
gpio_out.write(not value)

gpio_in.close()
gpio_out.close()

API

class periphery.GPIO(path, line, direction)
class CdevGPIO(path, line, direction)

Character device GPIO

Instantiate a GPIO object and open the character device GPIO with the specified line and direction at the specified GPIO chip path (e.g. “/dev/gpiochip0”).

direction can be “in” for input; “out” for output, initialized to low; “high” for output, initialized to high; or “low” for output, initialized to low.

Parameters:
  • path (str) – GPIO chip character device path.
  • line (int, str) – GPIO line number or name.
  • direction (str) – GPIO direction, can be “in”, “out”, “high”, or “low”.
Returns:

GPIO object.

Return type:

CdevGPIO

Raises:
  • GPIOError – if an I/O or OS error occurs.
  • TypeError – if path, line, or direction types are invalid.
  • ValueError – if direction value is invalid.
  • LookupError – if the GPIO line was not found by the provided name.
class periphery.GPIO(line, direction)
class SysfsGPIO(line, direction)

Sysfs GPIO

Instantiate a GPIO object and open the sysfs GPIO with the specified line and direction.

direction can be “in” for input; “out” for output, initialized to low; “high” for output, initialized to high; or “low” for output, initialized to low.

Parameters:
  • line (int) – GPIO line number.
  • direction (str) – GPIO direction, can be “in”, “out”, “high”, or “low”,
Returns:

GPIO object.

Return type:

SysfsGPIO

Raises:
  • GPIOError – if an I/O or OS error occurs.
  • TypeError – if line or direction types are invalid.
  • ValueError – if direction value is invalid.
  • TimeoutError – if waiting for GPIO export times out.
class periphery.GPIO[source]

Bases: object

read()[source]

Read the state of the GPIO.

Returns:True for high state, False for low state.
Return type:bool
Raises:GPIOError – if an I/O or OS error occurs.
write(value)[source]

Set the state of the GPIO to value.

Parameters:

value (bool) – True for high state, False for low state.

Raises:
  • GPIOError – if an I/O or OS error occurs.
  • TypeError – if value type is not bool.
poll(timeout=None)[source]

Poll a GPIO for the edge event configured with the .edge property.

For character device GPIOs, the edge event should be consumed with read_event(). For sysfs GPIOs, the edge event should be consumed with read().

timeout can be a positive number for a timeout in seconds, 0 for a non-blocking poll, or negative or None for a blocking poll. Defaults to blocking poll.

Parameters:

timeout (int, float, None) – timeout duration in seconds.

Returns:

True if an edge event occurred, False on timeout.

Return type:

bool

Raises:
  • GPIOError – if an I/O or OS error occurs.
  • TypeError – if timeout type is not None or int.
read_event()[source]

Read the edge event that occurred with the GPIO.

This method is intended for use with character device GPIOs and is unsupported by sysfs GPIOs.

Returns:

a namedtuple containing the string edge event that occurred (either "rising" or "falling"), and the event time reported by Linux in nanoseconds.

Return type:

EdgeEvent

Raises:
  • GPIOError – if an I/O or OS error occurs.
  • NotImplementedError – if called on a sysfs GPIO.
close()[source]

Close the sysfs GPIO.

Raises:GPIOError – if an I/O or OS error occurs.
devpath

Get the device path of the underlying GPIO device.

Type:str
fd

Get the line file descriptor of the GPIO object.

Type:int
line

Get the GPIO object’s line number.

Type:int
name

Get the line name of the GPIO.

his method is intended for use with character device GPIOs and always returns the empty string for sysfs GPIOs.

Type:str
chip_fd

Get the GPIO chip file descriptor of the GPIO object.

This method is intended for use with character device GPIOs and is unsupported by sysfs GPIOs.

Raises:NotImplementedError – if accessed on a sysfs GPIO.
Type:int
chip_name

Get the name of the GPIO chip associated with the GPIO.

Type:str
chip_label

Get the label of the GPIO chip associated with the GPIO.

Type:str
direction

Get or set the GPIO’s direction. Can be “in”, “out”, “high”, “low”.

Direction “in” is input; “out” is output, initialized to low; “high” is output, initialized to high; and “low” is output, initialized to low.

Raises:
  • GPIOError – if an I/O or OS error occurs.
  • TypeError – if direction type is not str.
  • ValueError – if direction value is invalid.
Type:

str

edge

Get or set the GPIO’s interrupt edge. Can be “none”, “rising”, “falling”, “both”.

Raises:
  • GPIOError – if an I/O or OS error occurs.
  • TypeError – if edge type is not str.
  • ValueError – if edge value is invalid.
Type:

str

class periphery.EdgeEvent[source]

Bases: periphery.gpio.EdgeEvent

EdgeEvent containing the event edge and event time reported by Linux.

Parameters:
  • edge (str) – event edge, either “rising” or “falling”.
  • timestamp (int) – event time in nanoseconds.
class periphery.GPIOError[source]

Bases: exceptions.IOError

Base class for GPIO errors.