LIN / one wire connection

Hi,
I'm trying to use LIN (local interconnect network) to connect two different PICs in two different boards. The goal is to use only one wire to pass information between them...
I'm using MCP2021 component from Microchip to achive that, one in each board and each board has it's own
power supply.

My question is:
I will need the same ground for transmission / reception in the two boards? It's possible to do it with
"different" grounds? Please see the circuit in attachment.

Thanks.

Best regards

You can use different grounds and an opto isolator between the two PICs, but you will still need two wires to send the data (signal and return).

Your goal of one wire is not possible. You always need a return wire/connection along with the signal wire.

Hi,
Thanks for your repply but i'm missing something...
The goal of MCP2021 is to use only one wire in communication... the TX and RX comes in the LIN wire. If these was in the same board (same grounds) i would not have big doubts, but i have 2 different boards with 2 different grounds.

What you mean by "return wire"?

If i want to do a communication through one wire between two different boards what would be the best approach?

Thanks for your help.

Best regards

You need a common ground. So it's one wire (signal) and ground (return)
Just think of it like hooking up a battery, you need two wires.

Can i use the earth as common ground?

Thanks.

How far are the two devices apart? Why can't you run a second wire?

Hi,
The 2 boards are 20m apart. The main reason is the convention... it's to be used in heat pumper and in the market almost everyone does these with 4 wires (F+N+Earth+signal) between the 2 boards.
Please see the attached schematic... it's the power supply i'm using (i have the same in the other board). Can i do the modification in the 2 boards like in the schematic? The earth is to be connected to chasis!

Using these and with the correct programming can i do one wire communication? I will have the return path?

Do you think it's the best approach?

Thanks.