VelociBus Button Pads

Silicone button pads have a nice feel, operate silently, and each button is illuminated by an addressable LED. Each button pad is 4x4 buttons (16 buttons total), and they come in two sizes. Regular is 100x100mm, mini is 60x60mm. The 4x4 button pads can also be chained together in groups of up to 16 button pads (256 buttons total) and be controlled by a single serial port with VelociBus technology. An Arduino library provides event driven debounced buttons and button illumination controls. Button events include press, release, and long press. Illumination includes solid color, flashing, breathing, color wheel, and fade effects.

Features

• Intelligent modules offload work from main processor
• Up to 16 modules in one VelociBus serial chain
• 15 colors illumination
• Blink, breathe, wheel, and fade effects
• Brightness setting
• Polled and Event driven button input options

Specifications

• Regular module: 100x100mm board, 15x15mm buttons
• Mini module: 60x60mm board, 10x10mm buttons
• Communication is serial 38,400 baud
• Modules operate at 3.3V to 5V

Technology

• Each module has it's own ATmega328PB microprocessor
• Illumination LEDs are WS2812 type addressable color
• Double sided ENIG (gold plated) circuit board
• Soft and silent silicone buttons
• All modules are identical, module addressing setup is automatic
• Open Source; Electrical, mechanical, and code

VelociBus for Button Pads

• Up to 16 VelociBus modules can be connected to one microprocessor serial port in a loop arrangement.
• The last VelociBus module loops back.
• VelociBus module addresses are automatically assigned based on the distance from the microcontroller.

The physical arrangement of the button pad modules is not critical, as long as they form a chain and the last one loops back. The "Initialization & Diagnostic" example can be used to identify the board addressing, which can then be used as shown in the "Module Array Superclass" example to easily access the button panel array as a single object.

For more than 16 button pads, use more serial ports. For example, using the 8 PIO serial ports on a RP2040 can drive 128 button pad modules (2048 total buttons).

The recommended power supply is 5V.
These combinations of mixed logic/power voltages are allowed:

• 5V power, 5V logic
• 5V power, 3.3V logic†
• 3.3V power, 3.3V logic

^†For 3.3V logic with 5V power use a level shifter (e.g. voltage divider) on Rx.

Design Documents

Basic Schematic Diagram	Basic Schematic Diagram.pdf
PCB Gerbers: 100mm Module	O114A.zip
PCB Gerbers: 60mm Module	O116B.zip
Mechanical: 100mm Faceplate	100mm Button Pad Face.stl
Mechanical: 60mm Faceplate	60mm Button Pad Face.stl
Button Pad Firmware Source Code	Arduino.zip     View
Button Pad Arduino Library	FEARLESS_VelociBus_4X4BP.zip

Arduino Library

Functions: Initialization

• begin( Stream *serialport, uint8_t tries = 3 ) // returns true if board(s) are found
• setButtonReleaseEnable( boolean enable ) // button release event control
• setButtonHoldEnable( boolean enable ) // button long press event control

Functions: Illumination

• setLED( byte board_address, byte led_index, lamp_fcn fcn, color_code color )
• setLEDrow( byte board_address, byte row_index, lamp_fcn fcn, color_code color )
• setLEDcol( byte board_address, byte col_index, lamp_fcn fcn, color_code color )
• setLEDall( byte board_address, lamp_fcn fcn, color_code color )
• setBrightness( byte intensity )
• bumpBrightness( int increment )

Functions: Button Events

• setHandler( void (*handler)(uint8_t board_address, uint8_t button_index, button_event_code event ) )
• loop() // required, triggers event callbacks

Functions: Button Polling

• getButton( button_info *b )

Example Programs

• Initialization & Diagnostic
• Test Display
• Button Polling
• Button Event Callbacks
• Illumination FX
• Module Array Superclass
• Ambient Blinking

Build Pictures

60x60mm Size, reverse SMT LEDs

100x100mm Size, 5050 SMT LEDs

Breadboard Development, two 60x60mm modules

Test Panel, Four 60x60mm modules

Eurorack Panel, Eight 60x60mm modules