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Appendix H SPI Electrical Specifications
MC9S12ZVM Family Reference Manual Rev. 1.3
Freescale Semiconductor
785
Figure H-4. Derating of maximum f
SCK
to f
bus
ratio in Master Mode
In Master Mode the allowed maximum f
SCK
to f
bus
ratio (= minimum Baud Rate Divisor, pls. see
SPI Block Guide) derates with increasing f
bus
, please see Figure H-4..
H.1.1
Slave Mode
In Figure H-1. the timing diagram for slave mode with transmission format CPHA=0 is depicted.
Figure H-5. SPI Slave Timing (CPHA=0)
1/2
1/4
f
SCK
/f
bus
f
bus
[MHz]
10
20
30
40
15
25
35
5
SCK
(INPUT)
SCK
(INPUT)
MOSI
(INPUT)
MISO
(OUTPUT)
SS
(INPUT)
1
9
5
6
MSB IN
BIT 6 . . . 1
LSB IN
SLAVE MSB
SLAVE LSB OUT
BIT 6 . . . 1
11
4
4
2
7
(CPOL
=
0)
(CPOL
=
1)
3
13
NOTE: Not defined!
12
12
11
see
13
note
8
10
see
note