BR - thanks for your comments.
However, having to add another MCU board just to reflash the SAM seems like a bit of an overkill. Also, we have six SAMs in our basic configuration system - and up to 20 in the extended config - all need to be reflashed from a central management node (wired). RX / TX approach means buffering lines with Z-state (extra hardware) AND at least one select PIN per device (well, you could add a 5-bit address line but then you need a decoder on every SAM board - more hardware).
So native USB or JTAG are still better IMO. JTAG could be done with just 4 data wires + 2 power. USB - with 3 data + 2 power. Regardless of the number of slave devices. Both JTAG and USB can also be used for bidirectional data transfer, as well, so no additional wiring required..
The only 2 problems I have are:
- We are not really familiar with programming over JTAG
- I am a bit wary of relying on native USB for everything as there are too much noise I heard on various forums about it being a bit touchy. As we are going to have these devices in the field, I need something relatively rock-solid.
Thoughts?
Val