Datasheet

Chapter 12 Serial Peripheral Interface (S12SPIV4)
MC9S12XDP512 Data Sheet, Rev. 2.21
518 Freescale Semiconductor
12.2.3 SS — Slave Select Pin
This pin is used to output the select signal from the SPI module to another peripheral with which a data
transfer is to take place when it is configured as a master and it is used as an input to receive the slave select
signal when the SPI is configured as slave.
12.2.4 SCK — Serial Clock Pin
In master mode, this is the synchronous output clock. In slave mode, this is the synchronous input clock.
12.3 Memory Map and Register Definition
This section provides a detailed description of address space and registers used by the SPI.
12.3.1 Module Memory Map
The memory map for the SPI is given in Figure 12-2. The address listed for each register is the sum of a
base address and an address offset. The base address is defined at the SoC level and the address offset is
defined at the module level. Reads from the reserved bits return zeros and writes to the reserved bits have
no effect.
Register
Name
Bit 7 6 5 4 3 2 1 Bit 0
SPICR1 R
SPIE SPE SPTIE MSTR CPOL CPHA SSOE LSBFE
W
SPICR2 R 0 0 0
MODFEN BIDIROE
0
SPISWAI SPC0
W
SPIBR R 0
SPPR2 SPPR1 SPPR0
0
SPR2 SPR1 SPR0
W
SPISR R SPIF 0 SPTEF MODF 0000
W
Reserved R
W
SPIDR R
Bit 7 6 5 4 3 2 1 Bit 0
W
Reserved R
W
Reserved R
W
= Unimplemented or Reserved
Figure 12-2. SPI Register Summary