MC68HC08AS32 Datasheet, PDF (205/280 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Addr.
$0010
$0011
$0012
Register Name
SPI Control Register ^Read:
(SPCR) Write:
See page 221. _Reset:
SPI Status and Control Register ^Read:
(SPSCR) Write:
See page 223. _Reset:
SPI Data Register ^Read:
(SPDR) Write:
See page 225. _Reset:
Bit 7
SPRIE
0
SPRF
R
0
R7
T7
R
6
5
R
SPMSTR
0
ERRIE
0
R6
T6
1
OVRF
R
0
R5
T5
= Reserved
4
3
CPOL
CPHA
0
1
MODF SPTE
R
R
0
1
R4
R3
T4
T3
Unaffected by reset
Figure 14-3. SPI I/O Register Summary
2
SPWOM
0
MODFEN
0
R2
T2
1
SPE
0
SPR1
0
R1
T1
Bit 0
SPTIE
0
SPR0
0
R0
T0
14.4.1 Master Mode
The SPI operates in master mode when the SPI master bit, SPMSTR (SPCR
$0010), is set.
NOTE:
Configure the SPI modules as master and slave before enabling them. Enable the
master SPI before enabling the slave SPI. Disable the slave SPI before disabling
the master SPI. (See 14.13.1 SPI Control Register.)
Only a master SPI module can initiate transmissions. Software begins the
transmission from a master SPI module by writing to the SPI data register. If the
shift register is empty, the byte immediately transfers to the shift register, setting
the SPI transmitter empty bit, SPTE (SPSCR $0011). The byte begins shifting out
on the MOSI pin under the control of the serial clock. (See Figure 14-4.)
MASTER MCU
SLAVE MCU
SHIFT REGISTER
BAUD RATE
GENERATOR
MISO
MOSI
SPSCK
SS
MISO
MOSI
SPSCK
V_DD
SS
SHIFT REGISTER
Figure 14-4. Full-Duplex Master-Slave Connections
MC68HC08AS32 — Rev. 4.1
Freescale Semiconductor
Data Sheet
205