MC68HC912DG128 Datasheet, PDF (265/452 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Multiple Serial Interface
Serial Peripheral Interface (SPI)
Transfer
Begin
End
SCK (CPOL=0)
SCK (CPOL=1)
SAMPLE I
(MOSI/MISO)
CHANGE O
(MOSI pin)
CHANGE O
(MISO pin)
SEL SS (O)
(Master only)
SEL SS (I)
t_L
MSB first (LSBF=0):
LSB first (LSBF=1):
MSB
LSB
Bit 6
Bit 1
Bit 5
Bit 2
Bit 4
Bit 3
Bit 3
Bit 4
Bit 2
Bit 5
Bit 1
Bit 6
t_T t_I t_L
LSB Minimum 1/2 SCK
MSB
for t_T, t_l, t_L
Figure 14-5. SPI Clock Format 1 (CPHA = 1)
14.5.3 SS Output
Available in master mode only, SS output is enabled with the SSOE bit
in the SP0CR1 register if the corresponding DDRS is set. The SS output
pin will be connected to the SS input pin of the external slave device. The
SS output automatically goes low for each transmission to select the
external device and it goes high during each idling state to deselect
external devices.
Table 14-3. SS Output Selection
DDS7
0
0
1
1
SSOE
0
1
0
1
Master Mode
SS Input with MODF Feature
Reserved
General-Purpose Output
SS Output
Slave Mode
SS Input
SS Input
SS Input
SS Input
MC68HC912DG128 — Rev 3.0
MOTOROLA
Multiple Serial Interface
For More Information On This Product,
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Technical Data
265