Spi Examples With Different Spmode[Len] Values - Motorola MPC8260 PowerQUICC II User Manual

Part IV. Communications Processor Module

33.4.1.1 SPI Examples with Different SPMODE[LEN] Values

The examples below show how SPMODE[LEN] is used to determine character length. To
help map the process, the conventions shown in Table 33-2 are used in the examples.
Convention
1
Both __ and _ are used to aid readability.
Once the data string image is determined, it is always transmitted byte by byte with the lsb
of the most-signiÞcant byte sent Þrst. For all examples below, assume the memory contains
the following binary image:
msb
Example 1
with LEN=4 (data size=5), the following data is selected:
msb
with REV=0, the data string image is:
msb
the order of the string appearing on the line, a byte at a time is:
first
with REV=1,the string has each byte reversed, and the data string image is:
msb
the order of the string appearing on the line, one byte at a time is:
first
Example 2
with LEN=7 (data size=8), the following data is selected:
msb
the data string is selected:
msb
with REV=0, the string transmitted, a byte at a time with lsb first is:
first
with REV=1, the string is byte reversed and transmitted, a byte at a time, with
lsb first:
first
Example 3:
with LEN=0xC (data size=13), the following data is selected:
msb
33-8
Table 33-2. Example Conventions
gÐv
x
1
__
1
_
ghij_klmn__opqr_stuv
xxxj_klmn__xxxr_stuv
j_klmn__r_stuv
nmlk_j__vuts_r
nmlk_j__vuts_r
j_klmn__r_stuv
ghij_klmn__opqr_stuv
ghij_klmn__opqr_stuv
nmlk_jihg__vuts_rqpo
ghij_klmn__opqr_stuv
ghij_klmn__xxxr_stuv
MPC8260 PowerQUICC II UserÕs Manual
Description
Binary symbols
Deleted bit
Original byte boundary
Original 4-bit boundary.
lsb
lsb
lsb
last
lsb
last
lsb
lsb
last
last
lsb
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