You find the KiCad schematic and the layout in the kicad folder. I used this KiCad project for the PCB order at Aisler.
| Part | Value | Package | comment |
|---|---|---|---|
| C1 | 22µ/25V | E15-5 (axial) | consider the polarity |
| C2, C3 | 100n | C025-024X044 | |
| U1 | TSR_1-2450 | TSR-1 | consider the polarity 1 |
| U2 | ESP-C3-32S(4M)-KIT | ESP-C3-32S(4M)-KIT | consider the polarity |
| U3 | LEVEL-SHIFTER-4CH | LEVEL-SHIFTER-4CH | consider the polarity |
| R1 | 12K | Optional 2 |
1According to the discussions here and here TSR 1-2450 can be replaced by TSR 1-2450E.
2The documentation of AI-Thinker says this one should be connected, though the USB-Serial chip already pulls this pin.
The following photos show the assembled PCB
The AC provides the signals via the CNS connector. It has 5 pins with a pitch of 2.5 mm. It is out of the XH series from JST. The position of the connector is visible on the following photo of the AC indoor unit PCB.
The PCB of the remote control uses a pin connector out of JST JQ series also with a pitch of 2.5 mm. So the board can be directly plugged into the board of the AC.
It was not tested to directly plug the MHI-AC-Ctrl-ESP32-C3 into the AC unit. Instead, we recommend using an extender cable (called "4S balancer JST-XH extension cable" with one male and one female connector), e.g. https://www.aliexpress.com/item/1005003669930722.html. On the board, you can solder a cable, e.g. https://www.aliexpress.com/item/4000800420412.html.
The JST connector provides +12V. The DC-DC converter TSR 1-2450 converts the +12V to +5V.
The ESP32-C3 SPI signals SCL (SPI clock), MOSI (Master Out Slave In) and MISO (Master In Slave Out) are connected via a voltage level shifter 5V <-> 3.3V with the AC. Direct connection of the signals without a level shifter could damage your ESP32-C3! Note that the CNS connector does not provide a Chip Select signal, this is generated internally on the ESP32-C3 and routed back through IO9 and IO10.