No no, they are only connected to the MCU via I2C, but their job is to expose 16 additional GPIOs, just like the ones on the MCU itself. You can connect up to 8 of these chips to a single ESP, which gives you an additional 128 GPIOs. Each chip is only 1 to 2 $/€.
Ah I see. Good to know. Thanks.
Got any you recommend? Preferably on Ali.
There are a bunch of different versions with different packages or even with SPI instead of I2C. I personally prefer the I2C DIP version (MCP23017-E/SP) because it is easy to solder. Best ask ChatGPT about the existing versions. Just (try to) make sure that you buy an original from Microchip, not from a Chinese copy cat.
There is also a concurrent chip design called PCF8575 from NXP that is also a good product with just some restrictions (again ask the AI).
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I absolutely agree, and I can only add that I’ve started my journey from:
- NodeMCU ESP8266 (Wemos D1 Mini clone)
- NodeMCU ESP-32 ESP-WROOM-32S CP2102
Without any issues, just reading the docs and adding configs, I managed to smartify my inverter and create a simple CO2 sensor with Wemos.
However, I ordered C6 as the next board to play with all fancy things like Zigbee, and most of the time, I’m busy seeking docs and configs to make this board useful.
Finally:
I have a working CO2 sensor at the C6 board after this:
I only managed to create a blinking LED after this:
The most essential things are working fine. I could recreate a simple interlock relay logically and physically, control external LED with GPIO, etc.
But I would not recommend this journey to the past version of myself if I could.
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This is quickly becoming one of my favorite boards. S3, POE, easy camera interface and works with raspberry pi cameras. USB C for optional power and flashing and an sdcard slot. Great for BT applications because WiFi isn’t used. If you look at the S3 lillygo version, which has POE but it costs the same as the board (or very close), has no USB C but that’s a non issue if you have a serial adapter but without POE you have to run cables to the board to power it.
While not getting to off topic it appears you can use the P4 now although I’m not an expert in PR’s. I wish I had snagged a wave share esp32-p4 with the POE shield but they are all out of stock and the full kits with touchscreen and camera are 80+ on AliExpress. Waveshare with POE hat is 25 with C6 for WiFi/BT… Pretty sure you need to run the dev version of ESPHome builder also. More of an FYI than to start a discussion but if I’m reading the PR wrong please correct me. If anyone has.a P4 to test any results would be appreciated.
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Amazing find 
Thanks for sharing!
Hi,
Was wondering if you could post a simple yaml for a BT Proxy (as a starting point) for the board you recommended please?
I found some step files for 3D Printing a case for it and it is a decent price with decent options (seems to be a Waveshare or Waveshare clone actually)?
Thanks a lot!