EM78P809N

8-Bit Microcontroller

 

shift start

 

 

 

 

 

 

 

shift start

SPIS

shift finish

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RBF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WBE

 

 

 

shift finish

 

 

 

 

 

 

 

 

 

 

 

 

/SCK pin

SO pin

a0

a1

a2

a3

a4

a5

a6

a7

 

b0

b1

b2

b3

b4

b5

b6

b7

SI pin

c0

c1

c2

c3

c4

c5

c6

c7

 

d0

d1

d2

d3

d4

d5

d6

d7

SPIF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SPID

a

 

 

 

 

 

 

 

c

b

 

 

 

 

 

 

d

 

write data

 

 

 

 

 

 

read data

write data

 

 

 

 

read data

Fig. 17. Transmit/Receive Mode (8-bit, 1 word)

(d) Multiple Device Connect (/SS):

When selecting external clock for transfer clock source, the /SS function can be used. This pin (/SS) will be active when the /SS function is enabled, else the /SS pin is a general purpose I/O. Ignore the data on the SDI and SDO pins while /SS is high, since the SDO is no longer driven.

Master

SDO SDI

SCK /SS

P67

P66

P65

P64

/SS SDO SCK SDI

Slave Device 1

/SS SDO SCK SDI

Slave Device 2

/SS SDO SCK SDI

Slave Device 3

/SS SDO SCK SDI

Slave Device 4

Fig. 18. The SPI Configuration Example of Single-Master and Multi-Slaves

Product Specification (V1.0) 07.26.2005

39

(This specification is subject to change without further notice)

Page 43
Image 43
IBM EM78P809N manual SCK pin, Multiple Device Connect /SS