MPC56xxx Byte Ordering and Bit Numbering

[tgc-yilmaz]

Hello,

MPC56xxx is used and Byte Ordering "Big Endian" is selected. At this point, there is confusion regarding bit ordering.

The Big Endian byte order is expected to be in the following format, but when the datasheet is examined, it is seen that it is as in the image below.

In the CW IDE, it was observed that the bits were positioned as expected. In this regard, can you provide detailed information about byte and bit ordering?

 

Thanks.

[lukaszadrapa]

Hi @tgc-yilmaz 

MPC56xx are Big Endian only devices. Little Endian cannot be configured/used ever.

The only catch here is that our reference manuals use bit numbering 0-31, not 31-0. That's due to some historical reasons.

Regards,

Lukas

[tgc-yilmaz]

Hello,

First of all, thank you for the answer. In this case, can I accept the general format for bit numbering for big endian, regardless of the reference manual?

Big Endian Order:

Byte 0	Byte 1	Byte 2	Byte 3
bits 31-25	bits 24-16	bits 15-8	bits 7-0

Thanks.

[lukaszadrapa]

Yes, in general, that's correct.

Regards,

Lukas