LadderButtons

Resistor Ladder Buttons

The LadderButtons.ino is a sample code for LadderButtonConfig which supports multiple buttons on a single analog pin. The buttons are distinguished by using a resistor ladder that sets the voltage to different values. The voltage can be read using the analogRead() function.

This program demonstrates 4 buttons using 4 resistors:

• 1 x SparkFun Pro Micro (clone)
• 4 x push buttons
• 1 x 4.7 kohm resistor
• 2 x 10 kohm resistor
• 1 x 47k kohm resistor

See Resistor Ladder for documentation on how to use the LadderButtonConfig class.

Circuit and Breadboard

The circuit above shows a 220 Ohm current-limiting resistor on Button 0. I was lazy and did not use it for this breadboard:

Sample Output

MODE_READ_BUTTONS

When LadderButtons.ino is compiled with:

#define MODE MODE_READ_BUTTONS

it reads 4 buttons connected to the A0 analog pin.

The sample output shows where each button was Pressed then Released. Blank lines were added for readability:

handleEvent(): virtualPin: 0; eventType: Pressed; buttonState: 0
handleEvent(): virtualPin: 0; eventType: Released; buttonState: 1

handleEvent(): virtualPin: 1; eventType: Pressed; buttonState: 0
handleEvent(): virtualPin: 1; eventType: Released; buttonState: 1

handleEvent(): virtualPin: 2; eventType: Pressed; buttonState: 0
handleEvent(): virtualPin: 2; eventType: Released; buttonState: 1

handleEvent(): virtualPin: 3; eventType: Pressed; buttonState: 0
handleEvent(): virtualPin: 3; eventType: Released; buttonState: 1

MODE_CALIBRATE

When the program is compiled with

#define MODE MODE_CALIBRATE

the values of analogRead() is printed as fast as possible. It will look something like:

1023
1023
1023
1023
...
23
24
23
23
23
...
332
333
332
333
333
...
513
514
514
515
514
514
...
842
843
843
842
843
...