Raspberry P0

A simple physical controller for change and view the current pedalboard with 2 buttons and 7 two segments displays

╔═══════════════════════════════════════════╗
║              P e d a l   P i           P0 ║
║                 ┌ ⎯  ⎯  ┐                 ║
║                 |⎥⎯⎜⎥ ⎜ |                 ║
║                 |⎥  ⎥⎯⎜.|                 ║
║                 └-------┘                 ║
║---------------------┬---------------------╢
║ ..=.............=.. | .........=......... ║
║ ....=.........=.... | ......=.....=...... ║
║ ......=.....=...... | ....=.........=.... ║
║ .........=......... | ..=.............=.. ║
╚═══════════════════════════════════════════╝

Documentation:

https://github.com/PedalPi/Raspberry-P0#raspberry-p0

Code:

https://github.com/PedalPi/Raspberry-P0

Python Package Index:

https://pypi.org/project/PedalPi-Raspberry-P0

License:

Apache License 2.0

Elements list:

• 2 seven segments displays;
• 2 push buttons for Pedalboard change.

Installation

PedalPi components enable the extension of Pedal Pi - Application. Through them, opening services are offered. A list of components can be found in the Components repository.

Use the pip to install the PedalPi-Raspberry-P0

pip3 install PedalPi-Raspberry-P0

Create the program.py

The following example demonstrates a basic setup for the Pedal Pi - Raspberry P0. If you want to add other components, check the component list.

import sys
from signal import pause

from application.application import Application
from raspberry_p0.raspberry_p0 import RaspberryP0

application = Application(path_data="data/", address='localhost')
application.register(RaspberryP0(application))

application.start()

try:
    pause()
except KeyboardInterrupt:
    application.stop()

Start

python3 program.py

Schematic

The following image shows the connections between components and Raspberry Pi to the default configuration. If you wish to change the pins, refer to Configuration File.

Pins

The pins of the seven-segment displays are shared with each other. That is, the pin_a of display 1 is shorted with thepin_a of display 2, pin_b of display 1 is shorted withpin_b of display 2 and so on. However, this rule does not apply to common_pin, where each display must have its own control pin.

The used pins are:

Config identifier	Pin¹	Type	Function
pin_a	13	integer	Seven segments - Pin A
pin_b	6	integer	Seven segments - Pin B
pin_c	16	integer	Seven segments - Pin C
pin_d	20	integer	Seven segments - Pin D
pin_e	21	integer	Seven segments - Pin E
pin_f	19	integer	Seven segments - Pin F
pin_g	26	integer	Seven segments - Pin G
pin_dp	0	integer	Seven segments - Dot point pin
common_pins	[5, 1]	integer list	Seven segments - Common pins
common_anode	True	bool	True if the displays are anode. False if are cathode.
next_pedalboard	14	integer	Button - Set to next Pedalboard
before_pedalboard	15	integer	Button - Set to before Pedalboard
momentary_footswitch	False	bool	True if buttons are momentary. False if buttons are two state

¹ BCM pin numeration

Configuration file

It's possible changes the pins using a configuration file. The numbering of the pins corresponds to BCM. Isn't necessary to inform all configurations. An element not informed will be treated with your default value.

A Raspberry Pi pinout schematic can be seen in pinout.xyz.

The config_file has the following structure:

[display]
pin_a = 13
pin_b = 6
pin_c = 16
pin_d = 20
pin_e = 21
pin_f = 19
pin_g = 26
pin_dp = 0

common_pins = [5, 1]
common_anode = True

[pedalboard]
next_pedalboard = 14
before_pedalboard = 15

momentary_footswitch = True

[test]
test = False

For P0 to loads the new configuration, references the file in RaspberryP0 constructor.

# The config file has named as 'path/my_awersome_config.ini'.
application.register(RaspberryP0(application, configuration_file='my_awersome_config.ini'))

[display] Seven segments display

The seven-segment display consists of eight pins corresponding to the leds (pin_a topin_g and pin_dp) and two common pins (which are short-circuited).

There are two types of seven-segment displays: Cathode and Anode. common_anode informs if the displays are Anode or Cathode.

The image obtained from Circuits Today illustrates the correspondence of the pins with the LEDs.

Led pins

To save the amount of pins required for the project, the pins of the seven-segment displays are shared with each other. In this way, the pins corresponding to the pins leds (pin_a topin_g and pin_dp) must respectively be short-circuited to the displays. That is, the pin_a of display 1 is short-circuited with thepin_a of display 2, pin_b of display 1 is short-circuited withpin_b of display 2 and so on.

Config identifier	Default value	Type	Function
pin_a	13	integer	Pin A
pin_b	6	integer	Pin B
pin_c	16	integer	Pin C
pin_d	20	integer	Pin D
pin_e	21	integer	Pin E
pin_f	19	integer	Pin F
pin_g	26	integer	Pin G
pin_dp	0	integer	Dot point pin

Common pins

To describe the common_pin of the displays, a list of integers is used, where the significance of the digits follows the ascending order: the tens corresponds to the first element of the list and the units to the second element of the list.

Config identifier	Default value	Type	Function
common_pins	[5, 1]	integer list	Pin that controls the display view
common_anode	True	bool	True if the displays are anode. False if are cathode.

In Quora there is a tutorial on how you can identify if a display is cathode or anode.

[pedalboard] Push buttons

Simple push buttons were used to change the current pedalboard. For use with foot, is recommended use footswitches (like the temporary footswitch in image below). The two types of buttons the system supports are temporary buttons and two-state buttons (on-off).

Config identifier	Default value	Type	Function
next_pedalboard	14	integer	Set the current pedalboard for the next
before_pedalboard	15	integer	Set the current pedalboard for the before
momentary_footswitch	False	bool	True if buttons are momentary. False if buttons are two state

[test] Test

Config identifier	Default value	Type	Function
test	False	bool	Disable GPIOZero for development tests

Common questions

See FAQs on the wiki.

Examples