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Weekly Report

11

Jul

2015

Have fully integrated the new packet scheduler. This works great! I have the default number of link-layer retransmissions enabled (3) and this gives great reliability to my ping demo. I also added some debug GPIO so I knew what was going on when and things line up well enough (4 - 5ms of error between the coordinator and device slot timers ain't bad!).

I'm now looking into the AES-CCM* based security supplicant. I already had a supplicant that accepted messages to encrypted/decrypted but it didn't actually do any tranformation on the data. The CC2538 has an AES core built in where you pipe data in one end and encrypted data comes out the other. TI provides a library to do this, so I'm in the process of wiring it up. This is actually fairly simple once I figured out how the CCM mode operated (and understood the parameters L, M, a, m and c..!). I expect that once I get encryption working that decryption will be trivial (as you simply input the cipher text rather than the plain text and run the same algorithm on the data).

I'm pretty pleased with progress to date!