connection m0pro to Uno

Using Arduino Project Guidance
#1

I want to connect the Arduino m0pro as a slave and the Uno as a master via I2C.

I have everything set up. Jumpers btw. SCLs, SDAs, GND`s and 5V (from UNO) to Vin (on m0 pro)

My sketches are fairly simple and I just want to know if the m0pro receives commands from the Uno.

If I compile I dont get errors but nothing happens on the Serial Monitor either.

Does anyone know where my problem is and can give me advise?

(are the different operating voltages a problem?)

Thanks!

uno.ino (334 Bytes)

m0pro.ino (223 Bytes)

#2 
  Wire.beginTransmission(7);

  Wire.endTransmission(7);

Do you KNOW what beginTransmission() and endTransmission() do?

endTransmission:

Ends a transmission to a slave device that was begun by beginTransmission() and transmits the bytes that were queued by write().

You seem to have forgotten to write() anything.

Not that that really matters because on the M0 Pro, you don't read anything.

Put Serial.print() statements in setup(), too.

#3

(are the different operating voltages a problem?)

Yes.

I would expect that m0pro shows "2" on the serial debugging line, one per second. The UNO should show a "1" twice a second. The communication between the two doesn't happen because you don't send anything and because the receiving side has no code to handle incoming data.

If you don't see anything in the serial monitor for both boards it might be that you overloaded the power supply. How do you power the UNO?

In your setup I miss the I2C pull-ups. Maybe you have them but you didn't tell.

#4