gadgets.io

The classes of gadgets.io can be used outside of the gadgets system. They don’t depend on zeromq and don’t perform any of the gadgets communication.

IO

class gadgets.io.io.IO

All subclasses of Device have an ‘io’ property. It should return an object that provides this interface.

close()

close the io device

off()

turn the io device off

on()

turn on the io device

status

status of the io device

Counter

class gadgets.io.counter.Counter(pin, ticks)

Blocks for a given number of rising edges on a gpio pin.

wait()

Blocks until for the number of rising edges specified by self._ticks

GPIO

GPIOFactory GPIO

class gadgets.io.gpio.GPIO(pin, direction='in', pullup=False)

Turning on a pin using the linux sysfs interface requires you to:

• make sure the mux mode of the pin is set to gpio (which requires you to find out the name of the pin)
• figure out the number to write to /sys/class/gpio/export in order to enable the gpio interface
• write ‘out’ to /sys/class/gpio/gpio<gpio number>/direction
• write 1 to /sys/class/gpio/gpio<gpio number>/value

All this just to turn on a pin. This GPIO class takes care of all that for you. All you have to do is pick the port and pin (port 8, pin 3 in this case) and initialize a GPIO object like:

>>> from gadgets.pins.beaglebone import pins
>>> from gadgets.io import GPIO
>>> gpio = GPIO(pins['gpio'][8][3])

Now you can turn the pin on and off by:

>>> gpio.on()
>>> gpio.off()

If you want to use a gpio pin as input, you initialize it like this:

>>> from gadgets.pins.beaglebone import pins
>>> gpio = GPIO(pins['gpio'][8][11], direction='in')

You can then read the value of the pin by:

>>> print gpio.value
0

close()

Closes the file that GPIO uses to set/read the value of the pin.

home_dir

After a gpio pin is enabled the sysfs interface for the pin is created as a directory. This property creates the path to that directory.

mux_path

creates the full path to the sysfs mux interface for this pin.

off()

Sets the gpio pin low.

on()

Sets the gpio pin high.

value()

Get the value of the gpio pin.

Poller

class gadgets.io.poller.Poller(pin, timeout=None, edge='rising')

Poller performs a poll on a gpio line. Just call wait and it will block until the gpio pin goes high.

>>> from gadgets.pins.beaglebone import pins
>>> from gadgets.io import GPIO
>>> poller = Poller(pins['gpio'][8][3])
>>> poller.wait()

This will then block until the pin goes high.

close()

Closes the file descriptor that Poller uses for the Linux poll.

wait()

Blocks until the pin goes high

PWM

class gadgets.io.pwm.PWM(pin, frequency=20000, mux_path='/sys/kernel/debug/omap_mux')

Uses the pwm pins’ sysfs interface. You can use a pwm pin like this:

>>> from gadgets.pins.beaglebone import pins
>>> from gadgets.io import GPIO
>>> pwm = PWM(pins['pwm'][8][13])

Now you can turn it on and vary the duty percent:

>>> pwm.on() #turns the pin on with a 100 duty_percent
>>> pwm.duty_percent = 50

NOTE: The beaglebone pwm clock must be enabled before using this class. You can enable it by calling enable-pwm from the command line (requires gadgets and python-mmap to be installed)

duty_percent

Set the duty_percent with a value from 0 to 100. The value is written to the sysfs duty_percent interface. If the pwm was turned off before this call, the pwm will be turned on.

off()

turns off the pwm and sets the duty cycle to 0

on()

turns on the pwm and sets the duty cycle to 100