Texas Instruments MSP53C391, User Manual

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Interface Overview
3-2
3.1 Interface Overview
The MSP53C392 accepts data from the master microprocessor across the
eight data lines. The transfer of data is controlled by two control lines (R/W and
STROB). The data is loaded to an internal buffer and the synthesis process
reads the data from the internal buffer as needed. The MSP53C392 signals
that it is
not ready to accept data when the buffer is full, or there is some other
condition that would prevent the MSP53C392 from accepting new data. This
signal is communicated to the master microprocessor using BUSY signal.
The MSP53C392 accepts data across an 8-bit wide data connection that is
controlled using two control lines (R/W and STROB). Two operations must be
accomplished: 1) Determining if the MSP53C392 is ready to accept new data,
and if it is ready, 2) writing new data to the MSP53C392.
Two control lines are provided to enable the master microprocessor to accom-
plish these two tasks, STROB and R/W.
The R/W line determines whether a read or a write operation is done to the
MSP53C392 when the STROB is pulsed low. If the R/W is high, than a read
from the MSP53C392 is done when the STROB is pulsed low. If the R/W is low,
then data is written to the MSP53C392 when the STROB is pulsed low.
The BUSY signal shares the same pin as the DATA7 signal. During a read op-
eration, this signal goes high to signal that the MSP53C392 is ready for a write
operation. If this signal is low during a read operation, then the MSP53C392
is
not ready for a write operation.
The EOS signal shares the same pin as the DATA6 signal. During a read op-
eration, this signal normally goes low, but goes high to signal that the
MSP53C392 has encountered an end-of-speech code in the data stream.
A negative going pulse on the INIT line can be used to reset the device. An INIT
pulse of 1
µ
s is enough to reset the device. Following the rising edge of the INIT
pulse, a delay of up to 5 ms will be required to permit the MSP53C391 and
MSP53C392 to completely initialize its internal condition.