A module to control the Explorer HAT Raspberry Pi Addon Board
Project description
Pibrella
Support code and API library for the Pibrella addon board.
Installation
The easy way
Python 3:
sudo apt-get install python3-pip sudo pip-3.2 install pibrella
Python 2:
sudo apt-get install python-pip sudo pip install pibrella
Alternative method
Alternatively you can clone this repository and install:
git clone http://github.com/pimoroni/pibrella cd pibrella sudo python setup.py install
To try the examples:
git clone http://github.com/pimoroni/pibrella cd pibrella/examples sudo python siren.py
Usage
Run as root!
Pibrella depends upon RPi.GPIO > 0.5.4, which requires root to access your GPIO.
If you’re using an interactive shell you should: sudo python -i, otherwise sudo python yourscript.py
First steps
To get started you need to import pibrella. Simply:
import pibrella
This will set up GPIO for you and collect all of the Pibrella’s inputs and outputs into some handily named objects.
If, for example, you wanted to turn on an LED you could:
pibrella.light.red.on()
And to turn it off again:
pibrella.light.red.off()
Pibrellas collections ( lights, inputs, outputs ) allow you to also control a group of things at the same time. So to turn all of the LEDs off you can simply:
pibrella.light.off()
Or on:
pibrella.light.on()
Blinking and pulsing LEDs
Lights aren’t simply there for toggling on and off. Any good lighting display needs pulsing, fading, blinking and strobing. Pibrella has functions for those, too:
pibrella.light.red.blink(ON_TIME, OFF_TIME)
And something more exciting:
pibrella.light.red.pulse(FADE_IN_TIME, FADE_OUT_TIME, ON_TIME, OFF_TIME)
The astute observer will realise that these are equivilent:
pibrella.light.red.pulse(0, 0, 1, 1) pibrella.light.red.blink(1, 1)
You can also fade LEDs from one brightness to another, like so:
pibrella.light.red.fade(0, 100, 2) # From 0 to 100% in 2 seconds
Inputs and outputs
The input and output collections correspond to the 4 in and 4 out pins of the Pibrella. These are named a, b, c, d for inputs and e, f, g, h for outputs- you’ll see these labels on the board itself.
To turn output “e” on, you can:
pibrella.output.e.on()
You can also write an explicit value, ( 1 is on/high, 0 is off/low ) like so
pibrella.output.e.write(1)
This is useful if you want to toggle a pin on and off programmatically, or write an input value directly to an output.
And you can write to the whole output collection simultaneously if you wish:
pibrella.output.write(1)
Inputs are similar, except you’re reading them instead of turning them on and off. To read a single input:
my_value = pibrella.input.e.read()
Or to read all inputs into a dictionary:
inputs = pibrella.input.read() input_e = inputs[‘e’]
The buzzer
The buzzer is just another output. However just turning it on and off wont get you much more than a single pop, it needs to be toggled rapidly to make a continuous tone. We’ve provided functions for this.
First, you can buzz at a specific frequency:
pibrella.buzzer.buzz( frequency )
Or play a note ( you can use both positive and negative values here, with 0 being A at 440Hz )
pibrella.buzzer.note( 1 )
Or play a built-in tone:
pibrella.buzzer.fail() pibrella.buzzer.success()
Handling events
If you want to catch an input changing state and run a specific function, you can use changed, pressed and released on any of the inputs or the button. Changed will trigger when a pin transitions from 1 ( high/on ) to 0 ( low/off ) or vice versa. Pressed will trigger when it transitions from 0 to 1, and Released when it transitions from 1 to 0.
For example:
- def button_pressed(pin):
print(“You pressed the button!”)
pibrella.button.pressed(button_pressed)
The “pin” parameter of the button pressed function is the Pibrella pin that triggered the event, in this case “pin” will be equal to “pibrella.button” so you can .read() it.
- def button_changed(pin):
- if pin.read() == 1:
print(“You pressed the button!”)
- else:
print(“You released the button!”)
pibrella.button.changed(button_changed)
If you want to turn a light on when the button is pressed, your code should look something like this:
import pibrella
- def button_changed(pin):
pibrella.light.red.write(pin.read())
pibrella.button.changed(button_changed)
And in just 4 lines, you’ve got started with event-driven programming!
Quick Reference
All of Pibrella’s inputs, outputs and lights are stored in collectons. You can reference a pin by name or by index in one of three ways:
pibrella.light[0] # By index pibrella.light[‘red’] # By name, for use with a variable pibrella.light.red # By name
You can also refer to a whole collection at once, simply by omitting the index or name:
pibrella.light
Help Text
Pibrella has a small amount of built-in help. If you want to know the names of the lights, inputs or putputs simply type:
pibrella.lights
Or otherwise, and you’ll get a list of the supported names.
Lights
The following methods are available for every Pibrella light:
.on() # Turn a light on .off() # Turn a light off .high() # Same as on .low() # Same as off
.toggle() # Toggle a lights status from on to off and off to on # If lights are pulsing/blinking toggle will always turn them off
.pulse( transition_on, transition_off, time_on, time_off ) # Pulse a light, values in seconds .blink( time_on, time_off ) # Blink a light, values in seconds .write( value ) # Turn on if value = 1, or off if value = 0
Outputs
An output can do everything a light can do, they are identical in all but name!
Inputs
The following methods are available for every Pibrella input:
General
pibrella.pause() # Wrapper for signal.pause(), great for pausing your application after calling blink, pulse or loop
pibrella.loop( function_name ) # Pass pibrella a function to run over and over again, asyncronously # You must call pibrella.pause() after giving it a function to loop, or your code will simply exit!
Change Log
1.2
Significant version bump to highlight launch to Production/Stable status
Small tweak to allow use of with, ie: “with pibrella.light.red as red:”
1.1.7-dev
Fixed buzzer to stop after playing melody
Wrapped changed/pressed/released so they can be registered simultaneously
Added “len” to pin collections, to support random.choice(pibrella.light)
Added error if run without root
1.1.6-dev
Populated LICENSE.txt
1.1.5-dev
Renamed amber to yellow and added alias support for backwards-compatibility
Added lights, inputs, outputs and pins as pluralalised aliases for light, input etc
Tweaked how on/off/toggle calls to lights/outputs are handled during pulse/blink
1.1.4-dev
Added pulse(), blink() and fade() to all outputs
1.1.3-dev
Built-in asyncronous alarm sound! pibrella.buzzer.alarm()
Replaced xrange with range
1.1.2-dev
Added support for REV 1 Raspberry Pi
1.1.1-dev
Added fade(from,to,duration) for lights
1.1-dev
Removed .all. keyword, use pibrella.input.read() instead of pibrella.input.all.read()
Added helper to list pins, try: pibrella.input in interactive shell
Added [‘name’] and [idx] support to pin collections, try: pibrella.input[0] pibrella.input[‘a’]
Added buzzer to pibrella.pin
Added return values to most methods
1.0-dev
Initial development/beta release
