ISD-T360SB Datasheet, PDF (47/109 Pages) List of Unclassifed Manufacturers – VoiceDSP Digital Speech Processor with Master/Slave, Full-Duplex Speakerphone, Multiple Flash and ARAM/DRAM Support

2—SOFTWARE
ISD-T360SB
When a command has more than one parame-
ter/return-value, the parameters/return-values
are transmitted in the order of appearance. If a
parameter/return-value is more than one byte
long, the bytes are transmitted from the most sig-
nificant to the least significant.
The MWRDY signal is used as follows:
1. Active (0) MWRDY signals the microcon-
troller that the last eight bits of data trans-
ferred to/from the voice module were
accepted and processed (see below).
2. The MWRDY signal is deactivated (set to 1
by the VoiceDSP processor) after 8-bits of
data were transferred to/from the
VoiceDSP processor. The bit is set follow-
ing the falling edge of the eighth MWCLK
clock-cycle.
3. The MWRDY signal is activated (cleared to
0) by the VoiceDSP processor when it is
ready to receive the first parameter byte
(if there are any parameters) and so on till
the last byte of parameters is transferred.
An active MWRDY signal after the last
byte of parameters indicates that the
command was parsed and (if possible)
executed. If that command has a return
value, the microcontroller must read the
value before issuing a new command.
4. When a return value is transmitted, the
MWRDY signal is deactivated after every
byte, and activated again when the
VoiceDSP processor is ready to send an-
other byte, or to receive a new com-
mand.
5. The MWRDY signal is activated (cleared to
0) after reset, and after a protocol time-
out. (See “INTERFACE PROTOCOL TIME-
OUTS” )
The MWRQST signal is used as follows:
1. The MWRQST signal is activated (cleared
to 0), when the status word is changed.
2. The MWRQST signal remains active (0), un-
til the VoiceDSP processor receives a GSW
command.
Figure 1-32 and Figure 1-33 illustrate the se-
quence of activities during a MICROWIRE data
transfer between VoiceDSP and the microcon-
troller.
INTERFACE PROTOCOL TIME-OUTS
Depending on the VoiceDSP processor’s state, if
more than 100 milliseconds elapse between the
assertion of the MWRDY signal and the transmis-
sion 8th bit of the next byte pertaining to the
same command transaction, a time-out event
occurs, and the VoiceDSP processor responds as
follows:
1. Sets the error bit in the status word to 1.
2. Sets the EV_TIMEOUT bit in the error word
to 1.
3. Activates the MWRQST signal (clears it to
0).
4. Activates the MWRDY signal (clears it to
0).
5. Waits for a new command. (After a time-
out occurs, i.e., the microcontroller re-
ceived MWRQST during the command
transfer, or result reception, the microcon-
troller must wait at least four milliseconds
before issuing the next command.)
ECHO MECHANISM
The VoiceDSP processor echoes back to the mi-
crocontroller all the bits received by the VoiceD-
SP processor. Upon detection of an error in the
echo, the microcontroller should stop the proto-
col clock, which eventually causes a time-out er-
ror (i.e., ERR_TIMEOUT bit is set in the error word).
NOTE
When a command has a return value, the
VoiceDSP processor transmits bytes of the
return value instead of the echo value.
The VoiceDSP processor transmits a byte as an
echo when it receives the value 0xAA from the
microprocessor. Upon detection of an error the
VoiceDSP processor activates the MWRQST sig-
nal, and sets the ERR_COMM bit in the error
word.
ISD
2-7