s908ab32ag0cfue Freescale Semiconductor, Inc, s908ab32ag0cfue Datasheet - Page 288

• Manufacturer Part Number: s908ab32ag0cfue
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface Module (SPI)
16.6.3 Transmission Format When CPHA = 1
Technical Data
288
CAPTURE STROBE
FOR REFERENCE
SPSCK; CPOL = 0
SPSCK; CPOL =1
SPSCK CYCLE #
FROM MASTER
SS
FROM SLAVE
;
TO SLAVE
MOSI
MISO
Figure 16-6. Transmission Format (CPHA = 1)
Figure 16-6
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.
Serial Peripheral Interface Module (SPI)
MSB
MSB
1
16.8.2 Mode Fault
shows an SPI transmission in which CPHA is logic 1. The
BIT 6
BIT 6
2
BIT 5
BIT 5
3
BIT 4
BIT 4
4
Error.) When CPHA = 1, the master
BIT 3
BIT 3
5
BIT 2
BIT 2
6
BIT 1
BIT 1
7
MC68HC908AB32
Freescale Semiconductor
LSB
8
LSB
—
Rev. 1.1