mc68hc912bc32 Freescale Semiconductor, Inc, mc68hc912bc32 Datasheet - Page 204

• Manufacturer Part Number: mc68hc912bc32
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Serial Interface
14.3.4 Bidirectional Mode (MOMI or SISO)
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 a serial data I/O (MOMI) pin for the master mode,
and the MISO pin becomes a serial data I/O (SISO) pin for the slave mode. The direction of each serial
I/O pin depends on the corresponding DDRS bit.
14.3.5 SPI Register Descriptions
Control and data registers for the SPI subsystem are described in this section. 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
14.3.5.1 SPI Control Register 1
Read: Anytime
Write: Anytime
SPIE — SPI Interrupt Enable Bit
204
When SPE = 1
Bidirectional
0 = SPI interrupts are inhibited.
1 = Hardware interrupt sequence is requested each time the SPIF or MODF status flag is set.
SPC0 = 0
SPC0 = 1
Normal
Mode
Mode
Address:
Reset:
Read:
Write:
Chapter 5 Operating Modes and Resource
SWOM enables open-drain output. PS4 becomes GPIO.
Serial Out
Serial Out
$00D0
Figure 14-14. Normal Mode and Bidirectional Mode
SPIE
Serial In
Serial In
Bit 7
SPI
SPI
0
Figure 14-15. SPI Control Register 1 (SP0CR1)
SWOM enables open-drain output.
Master Mode
SPE
MSTR = 1
M68HC12B Family Data Sheet, Rev. 9.1
DDS5
DDS5
6
0
SWOM
5
0
MOMI
PS4
MO
MI
MSTR
4
0
CPOL
SWOM enables open-drain output. PS5 becomes GPIO.
3
0
Mapping.
Serial Out
Serial Out
Serial In
Serial In
SPI
SPI
SWOM enables open-drain output.
CPHA
2
1
Slave Mode
MSTR = 0
DDS4
DDS4
SSOE
1
0
Freescale Semiconductor
LSBF
Bit 0
0
SISO
PS5
SO
SI