Master Microprocessor Interface Description
2-6
If the EOS signal is asserted high during the read operation, the end-of-speech
has been reached and a reset operation should be performed prior to sending
new commands or speech data. The reset can be done in one of two ways:
Pulsing the INIT pin low and then waiting for the MSP53C391 to re-initialize
itself or by writing two dummy bytes as described in the following.
RESET Operation
1) Perform a read operation to determine that both the EOS and BUSY sig-
nals are high.
2) If both the EOS and BUSY signals are high, write 2 bytes of dummy data
to the MSP53C391 by repeating the write operation four times as de-
scribed previously.
2.3.2
Method 2: Interrupt 1
In this method, the IRQ pin of the MSP53C391 is connected to an external in-
terrupt input pin of the master microprocessor. When the MSP53C391 is
not
busy and is ready to accept data, the IRQ signal goes low and provides a nega-
tive edge to trigger an interrupt in the master processor. This minimizes the
need to constantly poll the MSP53C391 while waiting for it to become ready
to accept new data.
Figure 2–2. MSP53C391 Interfacing Diagram (Method 2: Interrupt 1)
Output Port
Output Port
Output Port
I/O Port
I/O Port
I/O Port
I/O Port
INT
STROB
R/W
INIT
DATA3
DATA2/EOS
DATA1
DATA0
IRQ
EOS
15
7
9
16
1
2
3
MASTER
MICROPROCESSOR
MSP53C391
DAC+
DAC–
13
12
14
6
TO SPEAKER OR
AMPLIFIER/FILTER
NOTE A: IRQ:
Negative edge interrupt to master microprocessor when MSP53C391 is not busy and ready to accept data.
Содержание MSP53C391
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