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I <heart> Xmega

2010/09/10

So I’m working on a developing the ioStack code (still need to write something useful about that…) and am repeatedly reminded why I love to work with the Xmega.  At the moment, I have a single XmegaA3 acting as the “spider” of my protoboard.  It has a USB serial link connected to port F in order to provide the control interface to everything.  There are currently 4x “PDI5” interfaces configured for D0, D1, E0, and E1.  The PDI5 interface is my own invention, and consists of a sync serial port that’s able to switch between the AVR PDI protocol and normal serial, and is designed to connect to the target via a micro-B USB connector.  There’s a NRF24 wireless chip attached to port C, and ports A and B are currently unused.  The next step in my development is to work on getting the NRF24 tied in and running a multipoint protocol, but that depends on having a debug serial interface.  For some reason the A3 is missing a second serial interface on port F, so I’m just going to shut off one of the PDI5 interfaces and repurpose serial E1 for debug.  A few changes to the #defines in the code and I’ll be good to go!  Try doing that on most any other microcontroller, and you’ll be in for a lot of pain.

I just completed early bootstrapping of my latest project’s target board, but realized that for some reason I set the VID to 2.9V instead of 3.3V.  Obviously this will reduce current consumption on the board, but I didn’t quite think about the part where at least for a while I’ll need to interface it to 3.3V electronics.  For now I’ve just hooked up its +5v supply and am relying on the ability of the I/Os in the devices to run slightly out-of-spec.  It doesn’t hurt that there are series resistors built into the interface anyway…

The next step is to develop a basic multi-point wireless protocol over the NRF24 in order to link my NRF24+Xmega interface board up and power it directly from the PDi5 interface on the target, thus breaking the 2.9/3.3V problem.  Now that I’ve got the “spider” directly connected to several NRF24 targets, I can program all the multipoint microcontrollers without having the process halted by non-functional wireless protocols…

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