I’m having trouble getting output from my ATtiny84, which is programmed to use Arduino’s SoftwareSerial.
I reconstructed Nick Gammon’s RS485 network: Gammon Forum : Electronics : Microprocessors : RS485 communications
The Arduino is communicating with an ATtiny84, and I’m using MAX485’s not LTC1480s (see attached diagram). I burned the 8MHz bootloader onto the ATtiny, then uploaded Gammon’s slave sketch using Arduino as ISP. Then I uploaded the RS485 master sketch to the Arduino (master and slave sketches attached).
The trouble is I don’t think I’m getting any output from ATtiny pin 4 (PA4, the enable pin), whereas I am everywhere else along the signal chain. Is pin 4 (PA4) on the ATtiny not able to output a HIGH or LOW? Should I use one of the PWM pins, or is the problem elsewhere? Maybe the sketches contain code not covered by ATtiny (though I checked and it does handle SoftwareSerial, analogread(), etc)?
In Gammon’s diagram (attached), the 680 Ohm resistors mean (at least in my setup) that the A line on the MAX485 is always pulled high, is that right? On other diagrams I see 120 Ohm resistors between A & B lines, one at each end.
I feel like I’m close so I’d really like to get this last bit figured out. Thanks for your time!