David Pye

Hi, I'm trying to reverse a serial protocol between a device and its' battery as part of an OSS battery management firmware project. The battery sends packets to the device at regular intervals to prove it's alive (and genuine, I suspect...) without which the device won't run. All that changes each packet is the sequence number, and the last four bytes of the packet. I've not had any luck figuring out whether it's some kind of crc/checksum or a rolling code. The packets look as follows: (0x12 are...

Hi, I'm trying to reverse a serial protocol between a device and its' battery as part of an OSS battery management firmware project. The battery sends packets to the device at regular intervals to prove it's alive (and genuine, I suspect...) without which the device won't run. All that changes each packet is the sequence number, and the last four bytes of the packet. I've not had any luck figuring out whether it's some kind of crc/checksum or a rolling code. The packets look as follows: (0x12 are...