Chapter 14 Serial Peripheral Interface (SPIV3) Block Description
Freescale Semiconductor
MC9S12C-Family / MC9S12GC-Family
419
Rev 01.24
14.3.2.3
SPI Baud Rate Register (SPIBR)
Read: anytime
Write: anytime; writes to the reserved bits have no effect
The baud rate divisor equation is as follows:
The baud rate can be calculated with the following equation:
Bidirectional
1
0
Slave In
MOSI not used by SPI
1
Slave I/O
Module Base 0x0002
7
6
5
4
3
2
1
0
R
0
SPPR2
SPPR1
SPPR0
0
SPR2
SPR1
SPR0
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 14-5. SPI Baud Rate Register (SPIBR)
Table 14-6. SPIBR Field Descriptions
Field
Description
6:4
SPPR[2:0]
SPI Baud Rate Preselection Bits
— These bits specify the SPI baud rates as shown in
mode, a change of these bits will abort a transmission in progress and force the SPI system into idle state.
2:0
SPR[2:0}
SPI Baud Rate Selection Bits
— These bits specify the SPI baud rates as shown in
. In master mode,
a change of these bits will abort a transmission in progress and force the SPI system into idle state.
Table 14-5. Bidirectional Pin Configurations (continued)
Pin Mode
SPC0
BIDIROE
MISO
MOSI
BaudRateDivisor
SPPR
1
+
(
)
2
•
SPR
1
+
(
)
=
Baud Rate
BusClock BaudRateDivisor
⁄
=
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