Freescale Semiconductor MPC8260 - Manual (Page 1254)

Serial Peripheral Interface (SPI)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
38-8 Freescale Semiconductor
Figure 38-6. SPI Transfer Format with SPMODE[CP] = 1
38.4.1.1 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 38-2 are used in the examples.
Once the data string image is determined, it is always transmitted byte by byte with the lsb of the
most-significant byte sent first. For all examples below, assume the memory contains the following binary
image:
msb ghij_klmn__opqr_stuv lsb
Example 1
with LEN=4 (data size=5), the following data is selected:
msb xxxj_klmn__xxxr_stuv lsb
with REV=0, the data string image is:
msb j_klmn__r_stuv lsb
the order of the string appearing on the line, a byte at a time is:
first nmlk_j__vuts_r last
with REV=1,the string has each byte reversed, and the data string image is:
msb nmlk_j__vuts_r lsb
the order of the string appearing on the line, one byte at a time is:
first j_klmn__r_stuv last
Example 2
Table 38-2. Example Conventions
Convention Description
g–v Binary symbols
x Deleted bit
__
1
1
Both __ and _ are used to aid readability.
Original byte boundary
_
1
Original 4-bit boundary.
SPICLK
SPICLK
SPIMOSI
SPISEL
(From Master)
SPIMISO
(From Slave)
(CI = 0)
(CI = 1)
NOTE: Q = Undefined Signal.
msb lsb
lsb Q msb