Master Mode - Motorola MC68HC908GP32 Technical Data Manual

20.5.1 Master Mode

NOTE:
MC68HC908GP32 MC68HC08GP32
•
MOTOROLA
Freescale Semiconductor, Inc.
The following paragraphs describe the operation of the SPI module.
The SPI operates in master mode when the SPI master bit, SPMSTR, is
set.
Configure the SPI modules as master or slave before enabling them.
Enable the master SPI before enabling the slave SPI. Disable the slave
SPI before disabling the master SPI.
Register.)
Only a master SPI module can initiate transmissions. Software begins
the transmission from a master SPI module by writing to the transmit
data register. If the shift register is empty, the byte immediately transfers
to the shift register, setting the SPI transmitter empty bit, SPTE. The byte
begins shifting out on the MOSI pin under the control of the serial clock.
(See Figure 20-3.)
MASTER MCU
SHIFT REGISTER
BAUD RATE
GENERATOR
Figure 20-3. Full-Duplex Master-Slave Connections
Rev. 6
—
Serial Peripheral Interface Module (SPI)
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Serial Peripheral Interface Module (SPI)
(See 20.14.1 SPI Control
MISO
MOSI
SPSCK
SS
V
DD
Functional Description
SLAVE MCU
MISO
MOSI
SHIFT REGISTER
SPSCK
SS
Technical Data
307