this simple project was born from the personal need to solve an annoying problem with the bluetooth remote control of my JCW Pro exhaust. I am not responsible for any damage to third parties or objects, including the car. This publication is for the sole purpose of my memory.
The exhaust valve is controlled by a 12v powered control unit located in the trunk. The control unit is not a simple relay, the valve is controlled by a PWM circuit and opens / closes according to the supplied voltage. Not having an oscilloscope I was not able to determine the duty cycle of the PWM control, however by jumpering the control signal to GND I saw that the valve actually opens. Therefore, by inserting a relay after the control unit, it is possible to remotely control the jumper.
Using 3 t-tap junction connector I took: -12v (red cable coming from the fuse box) and GND (black cable going to the chassis from the control unit);
- PWM signal (cable indicated by the arrow).
As a relay I chose an ESP8266 wifi board (about 7-9 euros) and I created a simple firmware based on ESPHome (https://esphome.io). This creates a wifi access point called JCW PRO with password 12345678 and integrates a webserver to control the relay at page http://192.168.4.1 Being a simple wifi network and a web page, it is compatible with any device, iOS-Android-Windows etc. and future-proof.
The card I bought is this: https://www.amazon.it/dp/B07DJ4X4MX/?coliid=I1RMNTGA2TS3SI&colid=16RC7Q1DO2FU7&psc=1&ref_=lv_cv_lig_dp_it
On the board it's write ESP8266 RELAY V3 - LC TECHNOLOGY Pay attention that these cards exist in both 5v and 12v versions, the one you need is 12v.
Then the links:
12v (red cable) from the fuse box ---> +IN of the board
GND (black cable) from the spare black cable going to the chassis near the PWM control unit ---> -IN of the board
PWM (cable to be jumpered) ---> NO (for valve open by default) or NC (for closed by default)
Also a jumper between COM and -IN
I created the ESPHome firmware using the tool included in HomeAssistant (incredible home automation platform that I have been using with great satisfaction for years ( https://www.home-assistant.io/ ).
Different boards require modifications to the attached ESPHome sketch. I also attach .bin files ready to be flashed on my board using the tool ESPHome-Flasher https://github.com/esphome/esphome-flasher
Further developments, as soon as I have time, consist of cosmetic changes to the relay control web page and later an app.