MC68HCP11 Datasheet, PDF (29/45 Pages) Motorola, Inc – 8-Bit Microcontroller

7 Serial Peripheral Interface (SPI)
The SPI is one of two independent serial communications subsystems that allow the MCU to commu-
nicate synchronously with peripheral devices and other microprocessors. Data rates can be as high as
one half of the E-clock rate when configured as master, and as fast as the E clock when configured as
slave.
INTERNAL
MCU CLOCK
S
MISO
M
PD2
DIVIDER
÷2 ÷4 ÷16 ÷32
MSB
LSB
M
MOSI
8/16-BIT SHIFT REGISTER
S
PD3
READ DATA BUFFER
SELECT
SPI CLOCK (MASTER)
CLOCK
CLOCK
LOGIC
S
M
SCK
PD4
SS
PD5
SPI CONTROL
MSTR
SPE
SPI STATUS REGISTER
8
8
SPI CONTROL REGISTER
8
SPI INTERRUPT
REQUEST
INTERNAL
DATA BUS
Figure 9 SPI Block Diagram
DDRD — Data Direction Register for Port D
RESET:
Alt. Pin
Func.:
Bit 7
0
0
__
6
5
4
0
DDD5 DDD4
0
0
0
__
PD5/ PD4/
SS
SCK
3
DDD3
0
PD3/
MOSI
2
DDD2
0
PD2/
MISO
$1009
1
DDD1
0
PD1/
TxD
Bit 0
DDD0
0
PD0/
RxD
11 SPI BLOCK
MC68HC11A8
MC68HC11A8TS/D
MOTOROLA
29