Custom Dobiss master hardware

This solution to replace the master of this Dobiss lighting switch bus consists of:

• A Raspberry Pi 5 4GB

• A Raspberry Pi Pico

• A logic level shifter (Adafruit 4-channel I2C-safe Bi-directional Logic Level Converter - BSS138)

• A 1k Ohm resistor

• A SH-C30A DSD TECH USB to CAN Bus Adapter

  The Pi Pico handles the low level communication. It generates the reset pulse and requests the unique ID if a presence pulse is detected. THe unique ID is communicated to the Pi 5 by using serial over USB.

The Pi 5 acts as powersupply and processes the messages which are sent on the bus.

The low side of the logic level shifter is connected the 3.3 V pin (pin 1) and a ground pin (pin 9) of the Pi 5. One of its low side pins (A4) is connected to a GPIO pin (pin 20) of the Pi Pico.

The high side of the logic level shifter is connected to the 5V pin (pin 2) and a ground pin of the Pi 5. Finally a high side pin (B4) is connected to the data wire of the bus (D).

The bus itself (the D wire) is connected to the 5V pin with a 1K Ohm pullup resistor.