Regarding your questions about A/D conversion in the UAV DevBoard (UDB), relating to your plans for using a dsPIC30F40XX.
1. We tie the digital and analog power supplies together on the UDB. We have not seen any noise problem as a result. I think that is because the board is small, with very short connections. There are many low ESR, 0.1 uF caps distributed around the board, at least 13 of them, and a couple of 10 uF caps, I think that helps.
2. With regard to the requirements for supplying the A/D inputs, you should read the Microchip documents to make sure you understand what is needed. In the case of the accelerometer connections in the UDB, there is a 0.1 uF capacitor for each accelerometer input, connected from the dsPIC A/D input to ground. Take a look at the accelerometer section of the UDB schematic, you will see it. It is part of an anti-aliasing, low pass filter, but it also plays an important role in supporting the signal while it is being sampled. You will need to do something similar.
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