
2-8
2—SOFTWARE
ISD-SR3000
Voice Solutions in Silicon
1. The MWRQST signal is activated (cleared to 0), when the status word is changed.
2. The MWRQST signal remains active (0), until the ISD-SR3000 receives a GSW command.
Figure 2-37 illustrates the sequence of activities during a MICROWIRE data transfer.
Figure 2-37: Sequence of Activities During a MICROWIRE Byte Transfer
2.5.4
Depending on the ISD-SR3000’s state, if more than 100 milliseconds elapse between the as-
sertion of the MWRDY signal of the 8th bit of the next byte pertaining to the same command
transaction, a time-out event occurs, and the ISD-SR3000 responds as follows:
INTERFACE PROTOCOL TIME-OUTS
1.
2.
3.
4.
5.
Sets the error bit in the status word to 1.
Sets the EV_TIMEOUT bit in the error word to 1.
Activates the MWRQST signal (clears it to 0).
Activates the MWRDY signal (clears it to 0).
Waits for a new command. (After a time-out occurs, i.e. the host controller received
MWRQST during the command transfer, or result reception, the host controller must wait
at least four milliseconds before issuing the next command.)
2.5.5
The ISD-SR3000 echoes back to the host controller all the bits received by the ISD-SR3000.
Upon detection of an error in the echo, the host controller should stop the protocol clock, which
eventually causes a time-out error (i.e., ERR_TIMEOUT bit is set in the error word).
ECHO MECHANISM