MC68HC912B32MFU8 MOTOROLA [Motorola, Inc], MC68HC912B32MFU8 Datasheet - Page 93

• Manufacturer Part Number: MC68HC912B32MFU8
• Description: 16-Bit Microcontroller
• Manufacturer: MOTOROLA [Motorola, Inc]

13.3.3 SS Output
13.3.4 Bidirectional Mode (MOMI or SISO)
13.3.5 Register Descriptions
SP0CR1 — SPI Control Register 1
MC68HC912B32
MC68HC912B32TS/D
RESET:
When SPE=1
Bidirectional
Available in master mode only, SS output is enabled with the SSOE bit in the SP0CR1 register if the
corresponding DDRS bit 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.
In bidirectional mode, the SPI uses only one serial data pin for external device interface. The MSTR bit
decides which pin to be used. The MOSI pin becomes serial data I/O (MOMI) pin for the master mode,
and the MISO pin becomes serial data I/O (SISO) pin for the slave mode. The direction of each serial
I/O pin depends on the corresponding DDRS bit.
Control and data registers for the SPI subsystem are described below. The memory address indicated
for each register is the default address that is in use after reset. The entire 512-byte register block can
be mapped to any 2-Kbyte boundary within the standard 64-Kbyte address space. For more information
refer to 5 Operating Modes and Resource Mapping.
SPC0=0
SPC0=1
Normal
Mode
Mode
SPIE
Bit 7
0
SWOM enables open drain output. PS4 becomes GPIO.
DDS7
0
0
1
1
Serial Out
Serial Out
Serial In
Serial In
SPI
SPI
SPE
6
0
SWOM enables open drain output.
Figure 24 Normal Mode and Bidirectional Mode
SSOE
Master Mode
0
1
0
1
SWOM
MSTR=1
DDS5
DDS5
5
0
Table 30 SS Output Selection
SS Input with MODF Feature
MSTR
General-Purpose Output
4
0
Master Mode
MOMI
PS4
MO
SS Output
Reserved
MI
CPOL
3
0
SWOM enables open drain output. PS5 becomes GPIO.
CPHA
Serial Out
Serial Out
Serial In
Serial In
2
1
SPI
SPI
SWOM enables open drain output.
Slave Mode
SS Input
SS Input
SS Input
SS Input
SSOE
Slave Mode
1
0
DDS4
DDS4
MSTR=0
LSBF
Bit 0
0
MOTOROLA
SISO
PS5
SO
SI
$00D0
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