Thanks Steve & Rick, I now have .1uFs very close, a 10uF on DVcc and two 4.7uF's on AVcc, one near the MCU, the other on the analog board at the connector with another || .1uF. Eight of the 20 pins of the connector are ground wires separating the analog inputs. I tied them to GND on both ends, effectively making the two boards one. I had already taken GREAT pains on the intermeshing issues. Indeed, the devil is in the details. Subtle is the ground.
Regards to all, Garst Steve Underwood wrote: > > Hi Garst, > > The devil is usually in the details, when it comes to good layout. > > Make sure the gound plane really wraps around everything it can near the > MCU. Make it as interconnected as possible, to minimise the effects > breaks in the plane. Keep the 0.1uF *very* close to the relevant pins. > The 10uF would be better being near the MCU, it just isn't as critical > as getting the 0.1uF really close. Putting it on another board doesn't > seem the best choice. Don't be fooled into trying to make an analogue > ground plane and a digital ground plane, with only one point of contact > between them. That very rarely works, because it is rare for there to be > genuinely one point of contact. On those rare ocassions separate ground > planes connected very close to the MCU can be very good. One really > intermeshed plane is normally far better. > > Regards, > Steve
