println() function doesn't return Max485 to listening mode

[Hampton]

For me your "echo" example only partially works. I am using a MAX485 chip (not a module, just the DIP IC) wired up with a 120 ohm resistor between A/B. I can get messages from the Arduino on my PC, but I can't get the Arduino to echo back a message sent from my PC.

Edit: After poking around with the oscilloscope, it seems that the println function that says "hello world" at the beginning of the sketch is the culprit. Once that runs, the TX/RX control pin never returns to LOW, so the MAX485 stays in TX mode forever until you call set_mode(Auto485::RX) manually. Adding set_mode(Auto485::RX) after the initial println() call solves everything and the sketch works perfectly.

[Hampton]

It seems you didn't implement all the possible versions of the println function. You only redefined println(void), so all the other ones were just inherited from the Print class, meaning they didn't call set_mode(RX). After adding all the other function types to the library, the example works as expected.

[Hampton]

I've added a pull request with the fix for this issue.

[Michael Adams]

Thanks for investigating this. It's odd though, all the other println(...) methods call println(void) (e.g. hardware/arduino/avr/cores/arduino/Print.cpp#L117) so I would've thought I could just override that one method?

However if this is what is needed to fix it, who am I to argue :) Nicely implemented too, cheers.