Nordic-switch

Before building, read this carefully (especially PCB bugs / errata section and Safety guidelines)

This project aims to create a remote-controlled, smart light switch. The part presented here is the board that is embedded into the cord switch casing. It seems to work, however barely tested in the field (TL;DR it's quite dangerous and probably can combust spontaneously). Software was never fully developed, but you can take any example from Nordic SDK or even use Arduino.

The power supply is rated at 220V / 50 Hz. That's what I had at the moment. If the frequency or/and voltage is different you most likely will need to recalculate the supply.

Make sure you know what you're doing. It goes without saying that I'm not taking any responsibility for your actions. This device is not for beginners for sure.

PCB bugs / errata (READ CAREFULLY!)

• The main capacitor does not have a discharging resistor! Please install one externally. You will get a shock from the plug, even if device is disconnected from the mains!
• Some of the values are outdated, for example the C2 must be at least 220 uF;
• Zero-cross detection circuit is not assembled on my board. While in theory it should work, I dislike how it is designed. Use at your own risk;
• PCB power pad is missing. Find a place to inject power in the schematics.

Bringup

There are 3 solder pads underneath the board. Solder some thin wires to it (thicc ones will most likely rip the pads off the board). NEVER INTERFACE WITH THE DEVICE WHILE PLUGGED INTO MAINS! Inject the voltage from separate power supply while testing! Make sure your software runs well before testing the device plugged. In the software you need to ensure that:

• The Nordic SoftDevice is not using the LF crystal (since there is no any). Nothing will work without this step!;
• All power saving options possibly activated;
• The triac control pin is inverted (0 is active, 1 is not active).

Some safety guidelines

• NEVER NEVER connect the switch to the computer while plugged into mains - you will have a 50 / 50 chance of burning everything. Use low-power 3.3 volt adapter while developing;
• Never touch any parts of the board while operational - you'd likely get shock;
• Never leave device unattended - it's not stable enough to trust it;
• Be generally in a good state of mind and follow what you are doing - it is easy to make mistakes and burn your stuff

TODO

• Minor board fixups;
• Proper casing (I just used the one from the real switch, with drilled-out insides;
• Tests Tests Tests! Make sure device can work reliably and it is rated for conditions of the power mains.

Further discussion

(I wrote some really silly description at https://cringe.page/content/switch/switch.html)

I'll try to update the PCB and build the second revision in the future. If you assembled device and it worked / not worked for you - please share your stories