Faikin board ATE

The Faikin boards are a development board, a component to fit in to your Daikin air-con as your own project.

However, I do try and make sure they work before shipping, which means some testing. This means flashing some code and doing some tests.

Basically, there is always a small risk of badly placed, badly soldered, or faulty components on any board. It is rare, often less than 1 in 500 boards. But it is a risk.

TC2030-USB

The key component is a TC2030 lead - it means a simple pattern of pads and holes on the PCB (which essentially has no cost), and a suitable lead (which costs a bit more).

Oddly TC2030 seems to be one of the very few sprung pin header leads you can get for this. I would have expected way more, but they do seem pretty common and standard, and they just work.

The lead allows me to power the board and connect to USB to flash the processor module (ESP32-S3-MINI-1-N4R2). The programming batch process is pretty slick. I end up doing several in parallel and putting in anti-static bags, all pretty slick now. Yes, manual labour which I am not used to, but I am getting good at it. Amazingly the process of then labelling the bags takes pretty much the same amount of time.

The flashed code then operates the LED on board so I know it is all flashed and working. Simple. Basically, to get as far as an LED means partition table, boot loader, and code, all working (all signed and checked) to get as far as the sequence for a WS2812 LED. So this is not just some GPIO happens to be low, this is proof of code running cleanly - a good test.

But this only tests the USB, power, reset, and ESP32-S3 module and flash and RAM. Not all of the other electronics for Tx and Rx with the Daikin. These extra bits have some components because they have to level shift to 5V open drain logic with pull ups as used by Daikin.

TC2030-USB+

Can I test these remaining components? Well yes, I can...

The trick is to take the final pins that go to the Daikin for Tx and Rx, and feed them on to two spare pins on the TC2030 spare pads.

Then I make a custom lead that has USB but shorts those two pads.

This means my code can do a loop back test on the final Tx/Rx from the Faikin board, and indicate red not green on the LED if it is not seeing a loop back.

This tests almost all of then components (there are a couple of ESD diodes which it doesn't test other than that they are not a short - but that works as a visual inspection mostly).

Always valuable lessons learned as I go.