Motorola MS4407 用户手册

SSI Interface

8 - 5

Data captured by the decoder is sent to the host.

All communication must use RTS/CTS handshaking as described in the Simple Serial Interface Programmer’s 
Guide, p/n 72-40451-xx. If hardware handshaking is disabled or bypassed, the WAKEUP command must be sent 
prior to all other communications, or else the first byte of a communication message may be lost during the 
decoder wakeup sequence.

ACK/NAK handshaking can be enabled or disabled. This handshaking is enabled by default and we suggest the 
option not be disabled. Disabling this handshaking may lead to communication problems, as handshaking is the 
only acknowledgment that a message was received, and if it was received correctly. ACK/NAK is not used with 
unpacketed decode data regardless of whether or not this option is enabled.

All communication with the decoder must use 8-bit data.

The Serial Response Time-out parameter is used to determine how long to wait for a handshaking response before 
trying again, or aborting any further attempts. Both the host and decoder should use the same value for this 
parameter.

Decoder

Data is captured 

by decoder

Host

(1)

ASCII data sent

A temporary change may be made to the Serial Response Time-out when the host takes longer to process 
an ACK, or longer data string. Frequent permanent changes are not recommended due to limited write 
cycles of non-volatile memory.