Hardware Interfaces Implementations

GPIO Implementations

RPi.GPIO implementation

class pidevices.RPiGPIO(**kwargs)

GPIO hardware interface implementation using RPi.GPIO library extends GPIO.

Raises

ImportError – If the rpigpio library is not installed.

property pwm_pins

A dictionary that contains instances of RPi.GPIO’s pwm class.

initialize()

Initialize RPi.GPIO mode. By default it inializes to RPi.GPIO.BCM

read(pin)

Read the value of an input pin.

Parameters

pin (str) – The pin’s name.

Returns

that is 1 for high voltage, 0 for low voltage.

Return type

int

Raises

NotInputPin – Try to read from non input pin.

write(pin, value)

Write a value to an output pin.

Parameters

  • pin (str) – The pin’s name.

  • value (int) – The output value. The value should be 0 or 1 for a simple output pin and if it is pwm should be between [0, 1].

Raises

  • TypeError – Try to write non arithmetic value or use value greater than 1 or use negative value.

  • NotOutputPin – Try to write to an input pin.

remove_pins(*args)

Remove a pin/pins from the dictionary and free the resources.

Parameters

*args – String with the pin’s name, it could be more than one.

set_pin_function(pin, function)

Set a pin’s function.

Parameters

  • pin (str) – The pin name.

  • function (str) – The function value.

Raises

TypeError – Error occured using invalid function name.

set_pin_pull(pin, pull)

Set a pin’s pull up.

Parameters

  • pin (str) – The pin name.

  • pull (str) – The pull up value.

Raises

  • TypeError – Error occured using invalid pull name.

  • NotInputPin – Try to set pull up resistor to a non input pin.

set_pin_pwm(pin, pwm)

Set a pwm pin.

Parameters

  • pin (str) – The pin’s name.

  • pwm (int) – The pwm value.

Raises

  • TypeError – Invalid pwm type.

  • NotOutputPin – Error occured trying to drive a non output pin.

set_pin_frequency(pin, frequency)

Set a pwm pin’s frequency.

Parameters

  • pin (str) – The pin’s name.

  • frequency (int) – The frequency value.

Raises

NotPwmPin – Error occured trying to set pwm frequency to a non pwm pin.

set_pin_edge(pin, edge)

Set a pin’s edge value.

Parameters

  • pin (str) – The pin’s name.

  • edge (str) – The edge value.

Raises

NotInputPin – Try to set edge to a non input pin.

set_pin_bounce(pin, bounce)

Set a pin’s bounce time.

Parameters

  • pin (str) – The pin’s name.

  • bounce (int) – The bounce value.

set_pin_event(pin, event, *args)

Set the function that will be called with a new edge.

Parameters

  • pin (str) – Pin name

  • event (function) – Function pointer to the target function.

  • *args – The arguments of the target function.

Raises

NotInputPin – Try to set event to a non input pin.

wait_pin_for_edge(pin, timeout=None)

Wait pin for an edge detection.

Parameters

  • pin (str) – Pin name.

  • timeout (int) – The time until it stops waiting for an edge signal.

close()

Close interface.input

mcp23x17 chip family

Mcp23x17GPIO

class pidevices.Mcp23x17GPIO(**kwargs)

GPIO class implementation using mcp23x17 family chips. Extends GPIO

Parameters

**kwargs – Could be multiple keyword arguments in the form of pin_name = pin_number(pin number is A_x or B_x, because the implementation use the mcp23x17 devices.) For example for the hc-sr04 sonar, it would be echo=”A_1”, trigger=”B_2”.

initialize()

Initialize hardware and os resources.

add_pins(**kwargs)

Add new pins to the pins dictionary.

Parameters

**kwargs – Keyword arguments pin_name=pin_number. For example echo=”A_1”, trigger=”B_2”.

read(pin)

Read the value of an input pin.

Parameters

pin (str) – The pin’s name.

Returns

that is 1 for high voltage, 0 for low voltage.

Return type

int

Raises

NotInputPin – Try to read from non input pin.

write(pin, value)

Write a value to an output pin.

Parameters

  • pin (str) – The pin’s name.

  • value (int) – The output value. The value should be 0 or 1 for a simple output pin and if it is pwm should be between [0, 1].

Raises

  • TypeError – Try to write non arithmetic value or use value greater than 1 or use negative value.

  • NotOutputPin – Try to write to an input pin.

remove_pins(*args)

Remove a pin/pins from the dictionary and free the resources.

Parameters

*args – String with the pin’s name, it could be more than one.

set_pin_function(pin, function)

Set a pin’s function.

Parameters

  • pin (str) – The pin name.

  • function (str) – The function value.

Raises

TypeError – Error occured using invalid function name.

set_pin_pull(pin, pull)

Set a pin’s pull up.

Parameters

  • pin (str) – The pin name.

  • pull (str) – The pull up value.

Raises

  • TypeError – Error occured using invalid pull name.

  • NotInputPin – Try to set pull up resistor to a non input pin.

set_pin_edge(pin, edge)

Set a pin’s edge value.

Parameters

  • pin (str) – The pin’s name.

  • edge (str) – The edge value.

Raises

NotInputPin – Try to set edge to a non input pin.

set_pin_bounce(pin, bounce)

Set a pin’s bounce time.

Parameters

  • pin (str) – The pin’s name.

  • bounce (int) – The bounce value.

set_pin_event(pin, event, *args)

Set the function that will be called with a new edge.

In RPi.GPIO calling this function enables interrupt handling. In this implementation the start_polling() function need to be called in order to catch interrupts.

Parameters

  • pin (str) – Pin name

  • event (function) – Function pointer to the target function.

  • *args – The arguments of the target function.

Raises

NotInputPin – Try to set event to a non input pin.

start_polling(pins)

Start polling for interrupts the specified pins.

Parameters

pins (list) – List with the names of the target pins to be polled.

stop_polling()

Stop polling for interrupts

wait_pin_for_edge(pin, timeout=None)

Wait pin for an edge detection.

Parameters

  • pin (str) – Pin name.

  • timeout (int) – The time until it stops waiting for an edge signal.

Returns

Indicating if the interrupt occured.

Return type

int

Raise:

NotInputPin: Can’t wait for edge to a non input pin.

close()

Close interface.input

Mcp23017GPIO

class pidevices.Mcp23017GPIO(bus=1, address=32, **kwargs)

GPIO class implementation using mcp23017 chip. Extends Mcp23x17GPIO

Parameters

  • bus (int) – Optional argument for specifying the i2c bus of the mcp23017 module. Defaults to 1.

  • address (int) – Optional argument for specifying the i2c address of the mcp23017 module. Defaults to 0x20.

  • **kwargs – Could be multiple keyword arguments in the form of pin_name = pin_number(pin number is A_x or B_x, because the implementation use the mcp23x17 devices.) For example for the hc-sr04 sonar, it would be echo=”A_1”, trigger=”B_2”.

initialize()

Initialize hardware and os resources.

SPI Implementations

Spidev implementation

class pidevices.SPIimplementation(port, device)

SPI imlementation wrapping spidev library. Extends SPI.

Parameters

  • port (int) – SPI port on raspberry pi.

  • devive (int) – SPI device of raspberry.

Raises

ImportError – If spidev is not installed.

read(n)

Read n words from spi

Parameters

n (int) – The number of bytes to read from spi.

write(data)

Write data to spi

Parameters

data (list) – A list with integers to be writter to the device.

read_write(data)

Writes data (a list of integer words where each word is assumed to have bits_per_word bits or less) to the SPI interface, and reads an equivalent number of words, returning them as a list of integers.

close()

Free hardware resources.

HWPM Implementations

Python periphery HPWM

class pidevices.HPWMPeriphery(pin)

Wrapper around python periphery pwm implementation extends HPWM.

This class need the periphery module to be installed. Also some configuration files need to be added to the system. More info in the repo’s README.

Parameters

pin (int) – The pin number in bcm mode.

Raises

ImportError – Error if the periphery library is not installed.

read()

Read from hardware pwm pin.

Returns

The duty cycle of the pwm pin.

Return type

float

write(value)

Write to the pwm pin.

Parameters

value (float) – The new duty cycle value.

close()

Free hardware resources.

I2C Implementations

SMBus2 implementation

class pidevices.SMBus2(bus)

Wrapper for smbus2 library extends I2C

Parameters

bus (int) – The i2c bus of the raspberry pi. The pi has two buses.

read(address, register, byte_num=1)

Read using the smbus protocol.

Parameters

  • address – The address of the spi slave

  • register – The register’s address.

  • byte_num – How many bytes to read from the device. Max 32

Returns

A list with byte_num elements.

write(address, register, data)

Write using the smbus protocol.

Parameters

  • address – The address of the spi slave

  • register – The address of the register inside the slave.

  • data – A list or a single byte, if it is a list max length 32 bytes. It is error prone so write less and make consecutive calls.

write_i2c(address, register, data)

Write using the i2c protocol

Parameters

  • address – The address of the spi slave

  • register – The address of the register inside the slave.

  • data – A list or a single byte, if it is a list max length 32 bytes.

read_i2c(address, byte_num)

Read using the i2c protocol.

Parameters

  • address – The address of the spi slave

  • byte_num – How many bytes to read from the device. Max 32

Returns

A list with byte_num elements.

read_write(address, register, data, byte_num)

Combined read and write command using the i2c protocol.

Parameters

  • address – The address of the spi slave

  • register – The address of the register inside the slave.

  • data – A list or a single byte, if it is a list max length 32 bytes.

  • byte_num – How many bytes to read from the device. Max 32

Returns

A list with byte_num elements.

close()

Free hardware resources.