Ordering 3D prints

I have a 3D printer, it is pretty good, but I decided to try ordering some 3D prints from JLC.

Price

The most obvious issue is price, and actually, it is good. I have 2 part 3D printed cases for my Faikin boards for $0.47, but the postage is actually more, making $1.52 delivered, (£1.13+VAT). This is actually pretty good.

Quality

This is perhaps more important - could I have printed myself better - well NO, really NO! The quality is amazing. Resin prints are always good compared to FDM, and these are post processed with sanding.

The precision is also amazing. These designs are made with exact edges, no margins. I thought this was a good test. Well they fit smoothly, and just stick, but not very firmly. This means the dimensions of the print are, well, pretty damn exact to tiny fractions of a millimetre.

The result is quite impressive.

Improvements

My case design are auto generated from the PCB, so as to make sure they fit exactly. I have now done a load of work to tweak these, adding 0.1mm more to the edges that lock and a tiny angle to snap to place. So will be trying those. Will be interesting to see if I can make it a tighter locking edge now.

But, for now, a tiny spot of glue makes a nice case, so selling these on Tindie.

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.

Some more of my videos

I have done a couple of videos on my circuit boards.

The fun one, I hope, is the "shopping channel" style one.

But also a more instructive one on making circuit boards.

And one on the Faikin boards specifically.

Evolution of my code and PCBs

One the last few weeks my code and PCB designs have evolved a bit!

EPD

This is still called EPD (E-Paper Display), but in practice it is now a general purpose signage system allowing a number of widgets to be displayed getting data from many sources. Making it work with the 2" and 2.4" waveshare LCDs was nice. I got my PNG code doing colour nicely for this, and alpha blending.

One aspect I was very pleased about was the display connection - the display has 8 pads/holes at 0.1" spacing for a normal 0.1" header pin strip. Making a board to work with this is easy and you solder top and bottom - done! But it makes it almost impossible to remove cleanly if ever needed.

The trick is a surface mount header on my board, on top of pads/holes to allow for longer pins. This then allows 0.1" header pins on the display that then just plug in. It can be unplugged simply if access needed for connectors, or if changing display/board at any point. 

But the code has evolved even more - allowing a wide number of sensors (I2C and one-wire-bus), and formatting specially for temperatures (small C/F, colour based on range), etc. And now even BLE based temperature and humidity sensors as well.

In fact, with all of the sensors reporting to Home Assistant, I have had to make a "non display" version of the code for someone that is using this with no display - which is crazy for code designed to display stuff.

I also added handing of buttons as the board (see below) has them, causing Home Assistant triggers.

Faikin Remote

This other code has worked very much in parallel with a lot in common - including adding a load of sensors, the same as EPD. The main use case is to work a Faikin.

However the PCB design for this has ended up being a key module for use with my EPD code. It too has changed.

The initial sensors were temperature (as main thing for Faikin remote), humidity, and CO₂. The module is designed to also work a fan and radiator based - fan based on humidity and CO₂, and radiator based on temperature for cases where you have air-con and radiator. But it works for rooms I have that only have radiator, obviously. So it is an environmental monitor (working with HA) and a remote for the Faikin.

It also has pressure, so the CO₂ can be calibrated, and a light sensor so it can go off when dark (ideal for a bedroom).

But it is growing, with my latest designs (not yet on sale) having a microphone for noise level, and also an IR remote receiver. The idea of the IR is that a Daikin remote could work this directly. I'll need to code these soon.

It is becoming a really comprehensive environmental monitoring board now.

I was also asked to make the snap off bits (button, CO₂, and now IR) have pads to allow them to be wired in, so that is done - you can remove and mount nearby and wire back to the board.

Practical uses

Obviously I have these working with Faikin modules, and have them working with radiators (with and without air-con), and in places just monitoring. Some customers have them around offices to monitor workspace environmental conditions.

One good use case with remote BLE sensors is the pub. Showing BLE sensors in various places, and the DS18B20 temperature probe from another of the boards in the cellar monitoring the beer cooler. The fact this is all visible from the bar now makes life easier, and highlights any out of temperature readings (like when someone opened the beer keg store room to put in a sensor).

What is ideal is this is all reported and logged and graphed on Home Assistant as well. Any issues with the beer/lager the bar staff can see if there is an issue with the cooler at a glance (as had happened a couple of times). We also have logs and graphs which helps when the engineer comes in to sort the cooler.

Next step is probably one monitoring all the fridges. I found these small BLE sensors manage to work inside a metal fridge, if you are close enough. They will still do their temp checks, but this will alert quickly in one place if any issues, and provide historical records nicely. Obviously we check these with a calibrated thermometer as well.

All I need to do now is find a source of the BLE sensors that still work and can be flashed with Telink Flasher. Any pointers welcome.

Tindie

Yes, the code and PCB design is all open source, and I have these on Tindie. I do a tad cheaper for collection from Aber if you are local. Check it out as there is quite a lot on there now.

Environmental monitoring

The new Faikin Remote have sold a few, nice. Thank you. Now on Tindie, and more coming soon. The BLE linking to Faikin is working really well now.

But ironically more have sold not as Faikin Remote, so far, but as environmental monitors. The boards have pressure, temperature (via many means), humidity, and CO₂.

What is even more amusing is that the monitoring is probably best done using my generic display signage code (EPD) as it has all the sensor code to allow display of the values. No link to Faikin, but links to Home Assistant, and simple http polling, and so on, for all sensors.

Irony on top of that is I have had to just make a version of my display code for no display, a blind version, as it is ideal for this monitoring application even when you have no display (data centres, etc).

Home and office monitoring of CO₂ levels is becoming more important as people realise how much of an impact a lack of fresh air really has.

Faikin Remote

We have done a lot of small PCB designs over the years, but by far the most popular is my Faikin board. Reports are that even Daikin have recommended it to people wanting Home Assistant integration! It allows control of a lot of Daikin air conditioners over WiFi, MQTT, web, and Home Assistant. Constantly improving, and easy to use with local working not cloud based.

My latest design idea is a rework of a previous "environmental monitor", but specifically targeted at the Faikin users. The concept is that it can be a display and control for the Faikin. Whilst some ducted Daikin have a wall mount control, it is not cheap, so this would work with those and the more typical wall mount Daikin that do not support a wall mount display.

Key functions would be:

• Display current state of air conditioning unit.
• Allow change of key settings (power, mode, fan speed, target temp).
• Remote temperature sensor to allow room temp to be referenced at the controller in "Faikin auto" mode.

But the idea is the board can work with no display as reference temperature or just an environmental monitor for Home Assistant without a Faikin involved.

This is the current board design.

The expensive CO₂ sensor would be optional as it adds over $20 to the cost. Both the tab for it, and the 5 way joystick button, could be snapped off for a purely display or monitoring application.

A Waveshare 2" display fits on the front. Full colour 240x320 pixel. It is designed to fit the header so it can be removed if needed to access WAGOs, etc. The display adds another $20 at least.

User interface

I want to make the user interface simple - anything beyond the basic controls for the aircon you have to do via web interface. That should make it easy to use.

The idea is a joystick allows change of target temp (up/down) or switch to other setting (left/right) and change of mode and fan speed, as well as simple push on/off.

Bluetooth

Whilst it can all work over WiFi and MQTT, my plan is to link to Faikin using BLE as well, both ways. So Faikin reports mode/status, and this advises control and current reference temperature. This should make it extra robust with no need for WiFi or internet to continue working. The plan is a simple announcement BLE, not a connection, much like the many cheap BLE temperature/humidity sensors that exist.

Sensors

The current set of sensors include:

• MCP9808 Ambient temperature sensor. This is highly regarded as a good temperature sensor.
• VEML6040 Ambient light sensor (with a night mode to turn off display) including colour.
• GZP6816D Atmospheric pressure sensor, and additional temp sensor.
• SCD41 CO₂ sensor, with humidity, and another temp sensor. This would be optional.
• DS18B20 connection 3 pin WAGO for more temperature sensors.
• Detecting remote BLE temperature sensor.

All of these would report to Home Assistant as needed, and also report control and one reference temperature of choice to Faikin.

And yes, too many temp sensors, so system will allow a config of which are used and per sensor offset (to allow for heat via PCB). I may even allow averaging of multiple sensors. It will be interesting to see how this all works. DS18B20 are great for adding an "outdoor" sensor to report to HA as well. 

Generic signage

My existing EPD app which is general signage will be extended to handle the sensors as things to display so this can be simply used as a generic environmental display (and HA integration). Indeed this is likely to be the first code I do for these new boards, without a Faikin link.

Packaging

The basic board needs to be sold with and without the SCD41 CO₂ module. The board is likely $30 and the SCD41 adds at least $20 to that, probably more like $30. Not everyone wants CO₂ and humidity. The fluctuating value of the dollar is a pain in this all.

And then I may package with Waveshare 2" display, 8 way 0.1" pitch header, and extra M2 screws. This is likely another $20 or even $30.

Maybe even with DS18B20 sensor as an option. These are quite cheap.

I am not sure I want to do 3D case printing, but I plan a number of STL files.

Tindie makes such options simple, so that is likely the main sales channel initially. We'll see about Amazon as well. Those with A&A accounts will be able to order direct as always.

Update

The first boards (no button) have arrived. I have decided I'll try the TI TMP1075 as an alternative temperature sensor. In practice it seems a DS18B20 is best as it is separate from the board, closely followed by the SCD41. The MCP9808 (and presumably the TMP1075) suffers from some local heating from the PCB. The GZP6816D is close to the ESP32 and so not good at all for temperature (it is there for pressure). The T6793 CO2 sensor is not good, gives silly values (yes, I checked, and this is not a driver error), is bulky, needs 5V (does not work on 3.3V) and is actually not that much cheaper than the SCD41. The VEML6040 light sensor works well, but is a fun exercise for the casework.

Comments

All comments welcome.,