What is it?

This is a backpack for the M4 receiver from adafruit (or equivalent, sold on tindie or ebay). Allows (almost) any button in your project be "pressed" remotely. This is especially useful when the buttons are difficult to (or out of) reach.

Why did you make it?

I made this backpack to be able to remotely control a 1-meter long Wise Clock 4 (128x16 5mm LEDs) placed high on a wall. The second photo shows the backpack connected to the Wise Clock 4 board. The M4 backpack can be attached to any other device by soldering 6 wires (4 buttons, Vcc, GND).

What makes it special?

The M4 receiver itself sources 20mA on each of the 4 output pins. To replace a normally-open push button, an inverter (NO gate) is required. This could be also achieved with one transistor (which I used) on each channel. Because the M4 receiver itself requires a strict 5V (+/- 0.2V) for power, the backpack also features an optional step-up converter. It supports two kinds of step-up converters: a miniature one sold here (tindie) by BBTech (the black little board in the first photo) and another very popular one sold on ebay (the red board).

The M4 receiver and transmitter (shown in the first photo) are not included in the kit. They can be bought from adafruit or even from sellers here on tindie (search for "wireless remote"). The step-up converter (red board in the photo) is included.