MC3S12RG128 Datasheet, PDF (483/546 Pages) Freescale Semiconductor, Inc – Microcontrollers

Pin Mode
Bidirectional
Chapter 17 Serial Peripheral Interface (SPIV3) Block Description
Table 17-4. Bidirectional Pin Configurations (continued)
SPC0
1
BIDIROE
0
1
MISO
Slave In
Slave I/O
MOSI
MOSI not used by SPI
17.3.1.3 SPI Baud Rate Register (SPIBR)
Module Base 0x0002
7
6
5
4
3
R
0
0
SPPR2
SPPR1
SPPR0
W
2
SPR2
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 17-5. SPI Baud Rate Register (SPIBR)
Read: anytime
Write: anytime; writes to the reserved bits have no effect
Table 17-5. SPIBR Field Descriptions
1
SPR1
0
0
SPR0
0
Field
Description
6:4
SPI Baud Rate Preselection Bits — These bits specify the SPI baud rates as shown in Table 17-6. In master
SPPR[2:0] mode, a change of these bits will abort a transmission in progress and force the SPI system into idle state.
2:0
SPI Baud Rate Selection Bits — These bits specify the SPI baud rates as shown in Table 17-6. In master mode,
SPR[2:0} a change of these bits will abort a transmission in progress and force the SPI system into idle state.
The baud rate divisor equation is as follows:
BaudRateDivisor = (SPPR + 1) • 2^{(SPR + 1)}
The baud rate can be calculated with the following equation:
Baud Rate = BusClock ⁄ BaudRateDivisor
MC3S12RG128 Data Sheet, Rev. 1.05
Freescale Semiconductor
483