Hi TI experts,
Can UCD let customer change/define pec/crc algorithm? Can I use FW calculation to in stead of HW calculation for PEC/CRC ? Do you have any sample code? thanks.
ex:
Case 1: (What UCD produced)
[S] B0 Write 79 [S] B1 Read 00 00 D4 NACK [P]
Case 2: (Get it from a 3rd party PSU)
[S] B0 Write 79 [S] B1 Read 00 00 81 NACK [P]
- Poly 0x07 is represent the caculation of f(x) = x^8 + x^2 + x^1 + x^0.
The PFC EVM code has its own PEC calculation code. See the pmbus_insertion function in pmbus_common.c. It's in the Drivers directory, under PMBus. The PFC EVM code is here:
I'm pretty sure that our PEC calculation is a perfect match for the PMBus spec. We've been using it for a long time, including in point of load and telecom applications, which are much more likely to require true PMBus. I suspect that the 0x81 you are getting comes because they are ignoring the B0 and 79. If you but B10000 into our algorithm, you will get 0x81. I can't really comment on the other results.
