Receiving garbage data between 2 system with softSerial

Im receiving alot of garbage data between my 2 systems, which is connected via a wire, as you can see on the picture of my project. Im 90% sure that the problem why i receive all that garbage data is from the wire cause the problem disappears when i disconnect the wire from the LCD system (on the left). I know a wire can act like an antenna but it haven’t been this bad before that I cant send anything from my keypad system to my LCD system because of all the noise its receiving. So do anyone know how i can fix it? :wink:

This was made in a school project and I wanted to finish it after.

Please post a wiring diagram. It's impossible to see how things are connected. Also schematics, since you must have made them before making PCB's. :slight_smile:

here you go its not 100% the same but there have been some fixes to the keypad from pin 0 and pin 1 to the communication cable. Its in danish

projekt.pdf (144 KB)

GOT this too :smiley:

Schematic_Diagram_2020-07-11_21-43-47.pdf (98.8 KB)

Schematic_Diagram_2020-07-11_21-43-36.pdf (98.8 KB)

You need to connect the grounds between the two boards. Also, please post your code in tags.

Will it fix it if i just use the same power supply?

matti1999:
Will it fix it if i just use the same power supply?

Yes, assuming the power supply ground is the same as the module ground. Usually it is.

It seems to have worked. How can it be that not having the same ground can make so much noise?

matti1999:
It seems to have worked. How can it be that not having the same ground can make so much noise?

Think "antenna".

Paul

matti1999:
It seems to have worked. How can it be that not having the same ground can make so much noise?

A voltage signal without a reference (i.e. ground) is completely meaningless. There's absolutely no way to get valid data from a voltage signal without a common reference/ground.