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S
Slave Address
Start
Bit
Figure 5-10 I
S
Slave Address
Start
Bit
Figure 5-11 I
Note: The first data byte in a write-bus cycle can be used as a user-predefined
control byte (e.g., to determine the location to which the forthcoming data
bytes should be transferred).
5.6
SHI PROGRAMMING CONSIDERATIONS
The SHI implements both SPI and I
operate as a slave device or a single-master device. Once the operating mode is
selected, the SHI may communicate with an external device by receiving and/or
transmitting data. Before changing the SHI operational mode, an SHI individual reset
should be generated by clearing the HEN bit. The following paragraphs describe
programming considerations for each operational mode.
MOTOROLA
ACK from
Slave Device
0
A
First Data Byte
R/W
2
C Bus Protocol For Host Write Cycle
ACK from
Slave Device
1
A
Data Byte
N = 0 to M
Data Bytes
R/W
2
C Bus Protocol For Host Read Cycle
2
C bus protocols and can be programmed to
DSP56009 User's Manual
SHI Programming Considerations
ACK from
Slave Device
A
Data Byte
N = 0 to M
Data Bytes
ACK from
Master Device
from Master Device
A
Last Data Byte
Serial Host Interface
ACK from
Slave Device
A
S, P
Start or
Stop Bit
AA0425
No ACK
1
P
Stop
Bit
AA0426
5-23
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