Serial Peripheral Interface (SPI)
7-320
MC68360 USER’S MANUAL
7.12.5.2 SPI COMMAND REGISTER (SPCOM). The SPCOM is an 8-bit read-write register
that is used to start SPI operation.
Bits 6–0—Reserved.
These bits should be written with zeros by the user.
STR—Start Transmit
When the SPI is configured as a master, setting the STR bit to one causes the SPI con-
troller to start the transmission and reception of data from/to the SPI transmit/receive buff-
ers (if they are configured as ready by the user).
When the SPI is configured as a slave, setting the STR bit to one when the SPI is idle
(between transfers) causes the SPI to load the transmit data register from the SPI transmit
buffer and start transmission as soon as the next SPI input clocks and select signal are
received.
The STR bit is cleared automatically after one system clock cycle.
7.12.5.3 SPI PARAMETER RAM MEMORY MAP. The SPI parameter RAM area (see
Table 7-16) begins at the SPI base address. This area is used for the general SPI parame-
ters. The user will notice that it is similar to the SCC general-purpose parameter RAM.
NOTE: The items in boldface should be initialized by the user.
Certain parameter RAM values (marked in boldface) need to be initialized by the user before
the SPI is enabled; other values are initialized by the CP. Once initialized, the parameter
76543210
STR
RESERVED
Table 7-16. SPI Parameter RAM Memory Map
Address
Name
Width
Description
SPI Base + 00
RBASE
Word
Rx BD Base Address
SPI Base+ 02
TBASE
Word
Tx BD Base Address
SPI Base+ 04
RFCR
Byte
Rx Function Code
SPI Base+ 05
TFCR
Byte
Tx Function Code
SPI Base+ 06
MRBLR
Word
Maximum Receive Buffer Length
SPI Base+ 08
RSTATE
Long
Rx Internal State
SPI Base+ 0C
Long
Rx Internal Data Pointer
SPI Base+ 10
RBPTR
Word
Rx BD Pointer
SPI Base+ 12
Word
Rx Internal Byte Count
SPI Base+ 14
Long
Rx Temp
SPI Base+ 18
TSTATE
Long
Tx Internal State
SPI Base+ 1C
Long
Tx Internal Data Pointer
SPI Base+ 20
TBPTR
Word
Tx BD Pointer
SPI Base+ 22
Word
Tx Internal Byte Count
SPI Base+ 24
Long
Tx Temp
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Freescale Semiconductor, Inc.
For More Information On This Product,
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