MC68HC908GT16 Datasheet, PDF (331/412 Pages) Motorola, Inc – Microcontrollers

Serial Peripheral Interface Module (SPI)
Transmission Formats
relative to the slower SPSCK. This uncertainty causes the variation in
the initiation delay shown in Figure 20-7. This delay is no longer than a
single SPI bit time. That is, the maximum delay is two MCU bus cycles
for DIV2, eight MCU bus cycles for DIV8, 32 MCU bus cycles for DIV32,
and 128 MCU bus cycles for DIV128.
BUS
CLOCK
MOSI
SPSCK
CPHA = 1
SPSCK
CPHA = 0
SPSCK CYCLE
NUMBER
WRITE
TO SPDR
INITIATION DELAY
MSB
BIT 6
BIT 5
1
2
3
INITIATION DELAY FROM WRITE SPDR TO TRANSFER BEGIN
BUS
CLOCK
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
WRITE
LATEST
TO SPDR
SPSCK = INTERNAL CLOCK ÷ 2;
2 POSSIBLE START POINTS
BUS
CLOCK
EARLIEST
WRITE
TO SPDR
SPSCK = INTERNAL CLOCK ÷ 8;
8 POSSIBLE START POINTS
LATEST
BUS
CLOCK
EARLIEST
WRITE
TO SPDR
SPSCK = INTERNAL CLOCK ÷ 32;
32 POSSIBLE START POINTS
LATEST
EARLIEST
SPSCK = INTERNAL CLOCK ÷ 128;
128 POSSIBLE START POINTS
LATEST
Figure 20-7. Transmission Start Delay (Master)
MC68HC908GT16 • MC68HC908GT8 — Rev. 2
MOTOROLA
Serial Peripheral Interface Module (SPI)
Technical Data
331