I’m doing an audio project using a couple of Arduino Pro Minis. Both are the 5-volt version. Arduino-1 will send Arduino-2 a signal using an optocoupler. Arduino-2 will control some text to speech audio components. To reduce the impact of noise on the audio side, I plan to use an optocoupler between Arduino-1 and Arduino-2.
The Broadcom/Avago HCPL-817-00AE is the specific optocoupler I’m considering (datasheet here).
I think a 220 Ohm resistor would be right for R1. I have some 1N4007 diodes for the extra diode.
What value of resistor would you recommend for R2?