Description of the Command Codes
3-21
MSP53C691 Software Description
11) When the MSP53C691 needs more FM data, it pulls OUTRDY low to send
a nibble back to the master. The master must read the nibble from the bus.
The MSP53C691 pulls OUTRDY low three more times to transfer a total
of four nibbles to the master. The four nibbles sent this time are 0, X, 2, and
3. The nibble X is interpreted as the number of FM data bytes requested
by the MSP53C691. The 2 and 3 characterize the request for FM data.
Most Significant
DATA LINES
DATA3
DATA2
DATA1
DATA0
0
0
0
1
First nibble sent
X
X
X
X
Second nibble sent
0
0
1
0
Third nibble sent
Least Significant
0
0
1
1
Fourth nibble sent
12) The MSP53C691 pulls INRDY low after sending the four nibbles request-
ing the FM data from the master.
13) The master must send 9 as a command (0x09), letting the MSP53C691
know that master is going to send FM data.
Most Significant
DATA LINES
DATA4
DATA3
DATA2
DATA1
DATA0
0
1
0
0
1
Command header sent
14) After receiving the 9 command, the MSP53C691 lowers INRDY again. In
response, the master must send another nibble as level 1 parameter,
letting the MSP53C691 know how many bytes of FM data it is going to
send. This number must be less than or equal to the number of FM data
requested by the MSP53C691. For example, the MSP53C691 may
request 8 bytes of data, but the master may want to send only 6 bytes of
FM data. Therefore, the master sends 0x6 to the MSP53C691.
Most Significant
DATA LINES
DATA4
DATA3
DATA2
DATA1
DATA0
0
X
X
X
X
Level 1 parameter sent
15) After the level 1 parameter nibble has been latched, the MSP53C691 pulls
INRDY low again, to get ready to receive the FM data. The master must
now start sending the FM data in response to each lowering of INRDY.
Note:
The master must send the exact number of FM bytes promised.
Summary of Contents for MSP53C691
Page 1: ...MSP53C691 Speech Synthesizer December 2000 MSDS Speech User s Guide SPSU020 ...
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