What precautions should I take when mixing analog audio and digital (uC control) on the same board? I don't want to hear the I2C bus in my speakers. I'm thinking about
- Separate power supplies
- Separate ground planes, with each part within its own ground plane
- A single connection over a ferrite bead between ground planes
- Lots of decoupling, preferably by RC instead of simply a C
- Slew rate control, esp. on serial buses (lots of edges!)
- Physical distance between both world
The RC decoupling may or may not be overkill, but it costs only a resistor.