Motorola DSP56012 User Manual

The SHI clock generator generates the serial clock to the SHI if the interface operates 
in the Master mode. The clock generator is disabled if the interface operates in the 
Slave mode. When the SHI operates in the Slave mode, the clock is external and is 
input to the SHI (HMST = 0). 

connections. It is the user’s responsibility to select the proper clock rate within the 
range as defined in the I

2

C and SPI bus specifications.

The Serial Host Interface programming model is divided in two parts: 

• Host side—see 

 

• DSP side—see 

 

through 

Figure 5-2  SHI Clock Generator

Figure 5-3  SHI Programming Model—Host Side

SHI

HMST

HMST = 0

HMST = 1

SCK/SCL

Divide By

1 or 8

Divide By 1

To

Divide By 64

HRS

HDM0–HDM5

SHI Clock

F

OSC

Divide

By 2

Controller

Clock

Logic

CPHA, CPOL, HI

2

C

AA0417k

0

I/O Shift Register (IOSR)

IOSR

23

AA0418