I’ve finally got my wireless relay board working (thanks to everyone here who helped ). However, the relay I have connected to digital pin 4 ‘clicks’ every second (precisely). Putting a scope on pin 4 shows a 500mV pulse every second that corresponds with the relay clicks. I found this web page (Using the ATmegaXXX Microcontroller) which states that digital pin 4 (Atmega pin 6) is also the ‘Serial clock’. I can’t help but wonder if I’m seeing a serial timing pulse or something.
Assuming the Serial Clock is the source of my one-second pulses, I have two questions.
Is there a way to disable the Serial clock without causing problems with serial communications (since I use that for my wireless interface)?
What pins should I use to drive my 8 relays?
a) Is it ok to use digitalWrite() on the analog output pins?
I should mention that I use two of the analog pins to talk I2C to my Real Time Clock.
PS I should mention that I’m not actually using an UNO board anymore. I’ve built my own board based on the UNO’s Atmega328-P chip.