You find the eagle schematic and the layout in the eagle folder. The Gerber data is in MHI-AC-Ctrl_v2.2_2021-01-22.zip. I used this Gerber data for the PCB order at JLCPCB.
| Part | Value | Package | comment |
|---|---|---|---|
| C1 | 22µ/25V | E15-5 | consider the polarity |
| C2, C3 | 100n | C025-024X044 | |
| LS1 | LEVEL-SHIFTER-4CH | LEVEL-SHIFTER-4CH | consider the polarity |
| U$1 | WEMOS-D1-MINI | WEMOS-D1-MINI | consider the polarity |
| U1 | TSR_1-2450 | TSR-1 | consider the polarity |
| X1 | JST 05JQ-BT | JST-XH-05-PACKAGE-LONG-PAD | consider the polarity |
and the following parts are only needed when externally a DS18x20 should be connected:
| Part | Value | Package | comment |
|---|---|---|---|
| R1 | 4k7 | R-EU_0207/10 | |
| X3 | JST-XH-03 | JST-XH-03-PACKAGE-LONG-PAD | consider the polarity |
The following photos show the assembled PCB (without R1 and X1, which are used in context of DS18x20 only).
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.
hint: For previous MHI-AC-Ctrl PCB layouts a different connector was used. Additionally, it was required to swap pins because there was no 1:1 connection. This is no longer valid for the latest PCB layout. With the latest PCB layout you can directly plug the MHI-AC-Ctrl PCB to the AC PCB -
The possibility to directly plug the MHI-AC-Ctrl PCB to the AC PCB makes it simpler, but the operation of MHI-AC-Ctrl inside the AC case could reduce slightly the WiFi signal strength. If you see that the signal strength is not sufficient (e.g. many WiFi disconnects) then you should use a cable (called "4S balancer JST-XH extension cable" with one male and one female connector) and locate MHI-AC-Ctrl outside of the AC case.
Before you assemble the PCB, please check this issue. For some ACs (e.g. SRK-ZSX serie) it's getting tight and there might be not enough space to plug-in the MHI-AC-Ctrl PCB to your AC board.
The JST connector provides +12V. The DC-DC converter TSR 1-2450 converts the +12V to +5V.
The ESP8266 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 ESP8266! In an early version I used a resistor voltage divider, but since the SPI of the AC has high impedance outputs, a voltage level shifter seems to be better. The voltage level shifters are bi-directional. That means the according ESP8266 pins (SCL, MOSI, MISO) could be inputs or outputs.
An external temperature sensor DS18x20 (e.g. DS18S20, DS18B20) is supported. If you want to connect a DS18x20 you assemble R1 (4k7) on the PCB. The signals for the DS18x20 are available at X2.
If you prefer to assemble X1 on the top of the PCB because e.g. you want to place the MHI-AC-Ctrl outside of the AC, you have to consider the direction of X1 as shown on the following photo.
