mc68hc912bc32 Freescale Semiconductor, Inc, mc68hc912bc32 Datasheet - Page 201

• Manufacturer Part Number: mc68hc912bc32
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

14.3 Serial Peripheral Interface (SPI)
The serial peripheral interface (SPI) allows the MCU to communicate synchronously with peripheral
devices and other microprocessors. The SPI system in the MCU can operate as a master or as a slave.
The SPI is also capable of interprocessor communications in a multiple master system.
When the SPI is enabled, all pins that are defined by the configuration as inputs will be inputs regardless
of the state of the DDRS bits for those pins. All pins that are defined as SPI outputs will be outputs only if
the DDRS bits for those pins are set. Any SPI output whose corresponding DDRS bit is cleared can be
used as a general-purpose input.
A bidirectional serial pin is possible using the DDRS as the direction control.
Freescale Semiconductor
÷
SP0BR SPI BAUD RATE REGISTER
2
÷
4
INTERRUPT
REQUEST
÷
SPI
8
SAME AS E RATE
MCU P CLOCK
÷
16
DIVIDER
SELECT
÷
32
SP0SR SPI STATUS REGISTER
SPI CONTROL
Figure 14-11. Serial Peripheral Interface Block Diagram
÷
64
÷
128
÷
256
M68HC12B Family Data Sheet, Rev. 9.1
SP0DR SPI DATA REGISTER
SHIFT CONTROL LOGIC
8-BIT SHIFT REGISTER
INTERNAL BUS
MSTR
SPE
READ DATA BUFFER
SP0CR1 SPI CONTROL REGISTER 1
CLOCK
LOGIC
CLOCK
SWOM
LSBF
SP0CR2 SPI CONTROL REGISTER 2
Serial Peripheral Interface (SPI)
S
M
M
S
S
M
CONTROL
LOGIC
PIN
MISO
MOSI
SCK
PS7
PS4
PS5
PS6
SS
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