MC68HC12 MOTOROLA [Motorola, Inc], MC68HC12 Datasheet - Page 290

• Manufacturer Part Number: MC68HC12
• Description: The MC68HC912DT128A microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit
• Manufacturer: MOTOROLA [Motorola, Inc]

Multiple Serial Interface
16.5.1 SPI Baud Rate Generation
16.5.2 SPI Operation
Technical Data
290
The E Clock is input to a divider series and the resulting SPI clock rate
may be selected to be E divided by 2, 4, 8, 16, 32, 64, 128 or 256. Three
bits in the SP0BR register control the SPI clock rate. This baud rate
generator is activated only when SPI is in the master mode and serial
transfer is taking place. Otherwise this divider is disabled to save power.
In the SPI system the 8-bit data register in the master and the 8-bit data
register in the slave are linked to form a distributed 16-bit register. When
a data transfer operation is performed, this 16-bit register is serially
shifted eight bit positions by the SCK clock from the master so the data
is effectively exchanged between the master and the slave. Data written
to the SP0DR register of the master becomes the output data for the
slave and data read from the SP0DR register of the master after a
transfer operation is the input data from the slave.
Multiple Serial Interface
MC68HC912DT128A — Rev 4.0
MOTOROLA