mc68hc708mp16 Freescale Semiconductor, Inc, mc68hc708mp16 Datasheet - Page 260

• Manufacturer Part Number: mc68hc708mp16
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface Module (SPI)
13.6.3 Transmission Format When CPHA = 1
Technical Data
260
(FOR REFERENCE)
must be loaded with transmit data before the falling edge of SS. Any data
written after the falling edge is stored in the transmit data register and
transferred to the shift register after the current transmission.
Figure 13-6
figure should not be used as a replacement for data sheet parametric
information. Two waveforms are shown for SPSCK: one for CPOL = 0
and another for CPOL = 1. The diagram may be interpreted as a master
or slave timing diagram since the serial clock (SPSCK), master in/slave
out (MISO), and master out/slave in (MOSI) pins are directly connected
between the master and the slave. The MISO signal is the output from
the slave, and the MOSI signal is the output from the master. The SS line
is the slave select input to the slave. The slave SPI drives its MISO
output only when its slave select input (SS) is at logic 0, so that only the
selected slave drives to the master. The SS pin of the master is not
shown but is assumed to be inactive. The SS pin of the master must be
high or must be reconfigured as general-purpose I/O not affecting the
SPI. (See
begins driving its MOSI pin on the first SPSCK edge. Therefore the slave
uses the first SPSCK edge as a start transmission signal. The SS pin can
remain low between transmissions. This format may be preferable in
systems having only one master and only one slave driving the MISO
data line.
CAPTURE STROBE
SPSCK (CPOL = 0)
SPSCK (CPOL =1)
(FROM MASTER)
SPSCK CYCLE #
SS (TO SLAVE)
(FROM SLAVE)
Serial Peripheral Interface Module (SPI)
MOSI
MISO
13.8.2 Mode Fault
Figure 13-6. Transmission Format (CPHA = 1)
shows an SPI transmission in which CPHA is logic 1. The
MSB
MSB
1
BIT 6
BIT 6
2
Error.) When CPHA = 1, the master
BIT 5
BIT 5
3
BIT 4
BIT 4
4
BIT 3
BIT 3
5
MC68HC708MP16
BIT 2
BIT 2
Freescale Semiconductor
6
BIT 1
BIT 1
7
LSB
8
—
LSB
Rev. 3.1