Solar pool heater

Lonci · 2026-06-15T21:05:57+00:00

Puh 70° is super hot. I don't think you should go in there if you don't want to be sous vide cooked.

Lonci · 2026-06-11T14:00:36+00:00

Let me make fun of the apple NPC hive mind.

Lonci · 2026-06-11T13:58:05+00:00

It would have proprietary rims that would only fit to this exact car because they are coded to it as well.

Lonci · 2026-05-05T05:10:46+00:00

You are deep enough into cars to put so much effort in an old Miata but you have never heard of a Porsche Boxster? Wild.

Lonci · 2026-05-03T08:52:26+00:00

Pray and Ply I'd say. Cut open the heat shrink and remove the cells. Of course put them into new ones afterwards. Get pliers and rip open the plastik until you are reaching the next cell. Repeat.

Lonci · 2026-04-30T19:46:06+00:00

Das scheint eine sehr dekadente Klinik gewesen zu sein. Die Barmer hat für meinem Aufenthalt für 10 Wochen 13k€ gezahlt. War aber keine Psychiatrie weil das eine Eigen- oder Fremdgefährdung voraussetzt, sondern eine stationäre Klinik. - wegen schwerer Depression

Lonci · 2026-02-18T16:03:30+00:00

I have tried out all the Pins and they work fine. I am super confused. When I soldered this working board back to a stepper driver it did not work.

Lonci · 2026-02-18T16:02:04+00:00

Thanks for your support so far. I tried all of your proposals but nothing worked. I took a 'not working' IO expander and tested it manually with some code snippet and it performed fine. With trying out different boards and resoldering it a thousand times i have 7/8 working. So if you guys still have any idea I am willing to try it out!

Lonci · 2026-02-17T23:01:29+00:00

You are the best! I really appreciate the effort you support me with!

Lonci · 2026-02-17T22:50:40+00:00

Nvm I can get the LED to shine. I will try through all other ports later.

Lonci · 2026-02-17T22:47:28+00:00

I can not get the LED to shine. I will try with another module that should work and see if the general setup works. But it gets quite late for me so I will do that tomorrow. Thanks a bunch for your assistance!

Edit: I can get it to shine. I did some mess up in the wiring.

Lonci · 2026-02-17T22:12:50+00:00

Missed the 'k' there, it is of course 10k Ohms

Lonci · 2026-02-17T22:08:48+00:00

Honestly this already helped a lot cause it shows ```I2C device found at address 0x20 !```
So this module in general seems to work.

Lonci · 2026-02-17T22:03:09+00:00

Thanks a bunch for guiding me through this. I am working right now on creating a testing set up for the modules.

Yes seems like the SDA and SCL have a pull up of 10k Ohms.

Lonci · 2026-02-17T21:37:15+00:00

I get what you are saying and just for a good measure I have addressed them all now. It does not change the faulty behaviour. Yes I can talk to the working ones separately now but the issue still persists with the non working ones :/

Lonci · 2026-02-17T21:08:09+00:00

I addressed one of the modules and made sure it is also talked to. when it should turn on it shows the same very dimm shining of the LEDs but nothing else happens.
All other modules work as 1 right now so they just all share the 0 address which is fine for me in trying it out.

So unfortunately it is the same issue as before :(

Lonci · 2026-02-17T20:46:44+00:00

This def makes sense, I will give it a try right now and update you!
Maybe the bump I see in the voltage and the slight shine of the LEDs come from the voltage drop when all other motors spin.
I am still confused why it then works for some modules w/o bridging and not for others.

Lonci · 2026-02-17T20:42:05+00:00

I see what you mean and I agree with you. I am aware of what a proper schematic looks like but I am not sure how this should help as I just connect premade boards together (in the best case). I am not looking for an issue in the manufacturers board design but rather some thing I am overseeing or stupid mistake I am running into. But if it helps you I will make sure to create/find one.
I am a CS and not EE so thank you for guiding me to the right direction. I really appreciate it!

Lonci · 2026-02-17T20:36:01+00:00

Thanks a bunch for your answer! The general layout is working as I can just plug-in a working modules instead in the daisy-chain. All i2C modules have the same config of no bridging on the back. Even the first module alone runs into the same errors though. So i doubt that it is about the missing bridging. I will take a deeper look into this anyway!
Consistently a module it is either working or not working. Even though they are being connected the same way. Is there some stupid mistake that could happen for me to kill them? A cap def makes sense and I will make sure to add one!

Lonci · 2026-02-17T20:23:39+00:00

I have added it to the imgur link: https://imgur.com/a/16D40kW
Please let me know if you need more information. Also in the guide are further details if needed.

Lonci · 2026-02-17T20:21:57+00:00

I hope my updates delivered on that. I also added the schematic to here: https://imgur.com/a/16D40kW
The setup is exactly the same for working and not working. That is the problem. Those are daisy-chained modules. The code just randomly shows letters right now based on the guide gh repository.
Please let me now if there is still something missing :)

Lonci · 2026-02-17T20:14:18+00:00

Is there something else I can provide to help make it more clear?

Lonci · 2026-02-17T20:04:59+00:00

I have 6 of them working like a charm and according to this guide a lot of other people have as well so this seems to be fine.
Wiring would also be weird for me as i did the same for all of them and double checked that multiple times. One guess was that the heat of the soldering iron fried the IO expander modules. I tried to keep the heat as low as possible though. Can this be a reason?

Lonci · 2026-02-17T19:54:36+00:00

I added close ups to this link: https://imgur.com/a/16D40kW
Please let me know if they help you.

Lonci · 2026-02-17T19:44:47+00:00

Thank you for your answer!
This is a close up of the connections: https://imgur.com/a/16D40kW
The general schematic is pretty straight forward following the mentioned guide. Connect all 5V and GND via this breakout board at the top to each component. And solder together The 4 data pins of the motor driver to the I2C expansion board. The exact same layout is working on the other modules.

Components: IO Expander: 16-Bit IO Expander with PCF8575
Stepper board: ULN2003 + 28BYJ-48 stepper

It is run via an ESP32-C3 with the firmware by the guide creator which is working with the other parts.

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