I am using an ATTiny85 to control a dimmer module. I am trying to do is use an Arduino UNO to send a value from 0 to 100 percent to the ATTiny in order to control the dimming level. One-way communication is enough.
The problem is that the ATTiny only has one interrupt which is already used and required by the dimmer module. And since the SCL pin is the same as the interrupt pin, it cannot be used for I2C communication anymore.
I have tried using the SoftwareSerial library, but that somehow messed with the interrupt causing the light to flicker. I believe I read that using analogWrite on the UNO and analogRead on the ATTiny would be possible, but that a low-pass filter would be needed?
In short: Is there any easy way to send a value from the UNO to the ATTiny that does not rely on interrupts? A library, any kind of protocol, digital read/write, ...?
Since I have 3 pins left on the ATTiny I was thinking of using one as a signal pin and another as a value pin to send the value bit-by-bit from the UNO to the ATTiny. This, of course, would also require 2 pins on the UNO and on the UNO I need all the pins I can get. Or am I making things too complex?