Software Serial/ Moteino Mega to Nano

[jrdoner]

I am building a two processor gadget, using the Moteino Mega and a 5 v. Nano.  I get the impression from various internet sources that the 5 v. stuff will coexist with the Moteino Mega, as long as I keep 5 v. lines off the radio pins.   But I am attempting to establish a software serial link between the Nano and the Mega.  It definitely comes up and transmits data in both directions, as I can see by scoping the Rx and Tx lines.

However, neither chip seems to actually read the input from the other.  So does that mean that I've got to byte the bullet and put in level shifters?

It certainly would seem like data from the 5 v. side would be read by the 3.3 v. side.

[TomWS]

I am building a two processor gadget, using the Moteino Mega and a 5 v. Nano.  I get the impression from various internet sources that the 5 v. stuff will coexist with the Moteino Mega, as long as I keep 5 v. lines off the radio pins.   But I am attempting to establish a software serial link between the Nano and the Mega.  It definitely comes up and transmits data in both directions, as I can see by scoping the Rx and Tx lines.

However, neither chip seems to actually read the input from the other.  So does that mean that I've got to byte the bullet and put in level shifters?

It certainly would seem like data from the 5 v. side would be read by the 3.3 v. side.

The TX signal from the Nano to RX on the Mega needs to be level shifted to 3.3V (via 4.7K/10K resistor divider) but the Mega TX to Nano RX will be fine.

Tom