Other NXP ProductsのトピックRe: Configuration of two message buffer(MB) for reception with same ID !

Configuration of two message buffer(MB) for reception with same ID !

louizalaouiss — Mon, 28 Apr 2014 14:13:06 GMT

According to MPC5668 datasheet,
each Flexcan module has 64 MB (Message Buffers), each of them being configurable
for reception or transmission. Each MB has an ID field to allow reception of
frames which ID is the same as the one configured in the MB. I would like to
know what happens if two MB configured for reception are initialized with same
ID? A frame is received in both MB at the same time or only one MB will receive
the frame and what is the associated arbitration method?

thank you

Louiza

Re: Configuration of two message buffer(MB) for reception with same ID !

PetrS — Tue, 29 Apr 2014 11:35:21 GMT

Hi Louiza,

This scenario is described in the device Reference Manual in chapter 28.4.4 Matching Process (http://cache.freescale.com/files/32bit/doc/ref_manual/MPC5668xRM.pdf).

If 2 MBs are free to receive, a first message will be stored in the first MB (lower number). If the CPU does not service this MB (read the C/S word and then unlocked the MB) before another message with matching ID comes, this new message will be stored in second MB, otherwise it is going again into first one.

Regards,

Petr

Re: Configuration of two message buffer(MB) for reception with same ID !

louizalaouiss — Tue, 29 Apr 2014 12:46:40 GMT

Hi Petr,

thank you very much for the answer !

Regards,

Louiza :smileyhappy: