LayerscapeのトピックBit ordering in PBL

Bit ordering in PBL

tomhohenstein — Thu, 02 Aug 2018 09:51:32 GMT

In section 26.4.3 of the LS1046A reference manual (Rev. 1) the first byte of the PBL preamble is defined as follows:

Bit 0	Bit 1	Bit 2	Bit 3	Bit 4	Bit 5	Bit 6	Bit 7
1	0	1	0	1	0	1	0

Under the assumption that Bit 0 is the least significant bit, I would expect the first preamble byte to be 0x55. But when I dump the contents of the SD card I'm using I see that the first byte of the preamble is 0xAA instead.

So my question is:

Are the column labels of the PBL data structure in the reference manual in the wrong order or am I missing something else here?

Any help would be appreciated!

Re: Bit ordering in PBL

Pavel — Fri, 03 Aug 2018 02:32:39 GMT

Your picture shows 0xAA. See attached snapshots.

Bit0 = 1

Bit1 = 0

Bit2 = 1

Bit3 = 0

Bit4 = 1

Bit5 = 0

Bit6 = 1

Bit7 = 0

It is 0xAA.

Have a great day,
Pavel Chubakov

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Re: Bit ordering in PBL

tomhohenstein — Fri, 03 Aug 2018 07:04:51 GMT

Thank you for your answer, but I have to disagree with you.

The screenshots you posted does not represent the information from the table. The bit sequence you showed me in your screenshots starts with a zero in Bit 0.

I attached an edit of your screenshot to clarify what I mean.

But according to the reference manual Bit 0 should be 1.