mc9s12c32mpb16 Freescale Semiconductor, Inc, mc9s12c32mpb16 Datasheet - Page 430

• Manufacturer Part Number: mc9s12c32mpb16
• Description: Hcs12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 14 Serial Peripheral Interface (SPIV3) Block Description
The baud rate generator is activated only when the SPI is in the master mode and a serial transfer is taking
place. In the other cases, the divider is disabled to decrease I
14.4.5
14.4.5.1
The SS output feature automatically drives the SS pin low during transmission to select external devices
and drives it high during idle to deselect external devices. When SS output is selected, the SS output pin
is connected to the SS input pin of the external device.
The SS output is available only in master mode during normal SPI operation by asserting SSOE and
MODFEN bit as shown in
The mode fault feature is disabled while SS output is enabled.
14.4.5.2
The bidirectional mode is selected when the SPC0 bit is set in SPI Control Register 2 (see
this mode, the SPI uses only one serial data pin for the interface with external device(s). The MSTR bit
decides which pin to use. The MOSI pin becomes the serial data I/O (MOMI) pin for the master mode, and
the MISO pin becomes serial data I/O (SISO) pin for the slave mode. The MISO pin in master mode and
MOSI pin in slave mode are not used by the SPI.
430
Bidirectional Mode
When SPE = 1
Normal Mode
SPC0 = 0
SPC0 = 1
Special Features
SS Output
Bidirectional Mode (MOSI or MISO)
Care must be taken when using the SS output feature in a multimaster
system because the mode fault feature is not available for detecting system
errors between masters.
Serial Out
Serial Out
Table
Serial In
Serial In
Table 14-9. Normal Mode and Bidirectional Mode
SPI
SPI
BaudRateDivisor
Figure 14-11. Baud Rate Divisor Equation
Master Mode MSTR = 1
14-3.
MC9S12C-Family / MC9S12GC-Family
BIDIROE
Rev 01.23
=
NOTE
(
SPPR
MOMI
MOSI
MISO
+
1
DD
) 2
•
current.
(
SPR
Serial Out
Serial Out
+
Serial In
Serial In
SPI
SPI
1
)
Slave Mode MSTR = 0
BIDIROE
Freescale Semiconductor
Table
MOSI
MISO
SISO
14-9). In