Sunday, December 14, 2014

M4 receiver backpack for reliable wireless remote control

My investigation into the failure of the M4 receiver remote controlling my Wise Clock 4 concluded with the need to add a step-up converter. The Sure 1632 display makes the input voltage drop sometimes below the absolute minimum of 4.5V required for the M4 module to work properly. It's not the noise (spikes) in the 5V power, nor the interference on 315MHz.

I designed a simple "M4 receiver backpack" that uses a DC-DC step-up converter to ensure a 5V power for the M4 receiver module. The board supports 2 different kinds of converters, one from ebay (red in the photo below), the other from tindie (made by BBtech, black in the photo).

The backpack can be used, by default, without the step-up converter if the voltage is steady at around 5V. (A trace-jumper must be cut when a converter is added.)

The wireless remote pair of 4-key fob transmitter and receiver module is sold by Adafruit or vendors on ebay.

The assembled board wired to Wise Clock 4 is shown in the photos below. Note that only 3 out of 4 buttons on the remote have a function on the clock. Each button press could light up a (optional) LED on the receiver board for visual confirmation.

A new design of the Wise Clock 4 board should probably feature a header for plugging in the receiver module, otherwise the back of the board will show a bunch of ugly wires.

This M4 receiver backpack could be used for adding remote control to other devices with buttons, especially when these buttons are hard to access (due to enclosure design constraints), or hidden (for aesthetic purpose). One example that comes to mind is an oscilloscope clock fully enclosed in transparent acrylic; drilling holes for the buttons would require some design stretches.

Schematic and board layout are shown below.

The M4 receiver backpack would be also suitable for hacking old commercial alarm clocks. Please let me know if anyone is interested :)


  1. Just an idea, you can use 4th button to decrement items. I did it with my Xronos Clocks when using IR remote. Code change is minimum, i.e. if isDecrementing item--, else item++ :)

    1. Right. I only need to find a pin available :)

    2. Ah, sorry I didn't realize it's not ISP device...

  2. Hi Florin! We would like to feature this project on If you are interested, kindly drop me a message on my business e-mail: I'll be looking forward to your response! Thanks.