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Description of the Command Codes
3-17
MSP53C691 Software Description
10) When the MSP53C691 detects the end-of-speech, it pulls OUTRDY low.
11) The master then must read the data from the bus. Note that only the lower
four bits of the bus are valid data. OUTRDY goes low three more times af-
ter that, sending a total of four nibbles (0, 0, 5, and 5) if the speaking of the
phrase was successful.
12) INRDY goes low, indicating that the MSP53C691 is ready to receive a new
command. At this point the slave changes back to four-bit mode. Now the
master can send any command to the slave on the four-bit data bus
(DATA0–DATA3) with the DATA4 line pulled low. If the master must speak
again in eight-bit mode, repeat Steps 1 through 12.
Note:
The eight-bit interface is recommended for ADPCM.
The eight-bit interface does not support any interleaved commands (STOP,
volume control, etc.). Hold RESET low to stop speaking in the middle of a
phrase.
A header byte is embedded in the speech data to indicate which algorithm
(MELP, CELP, etc.) to speak. When a certain mode of data transfer is se-
lected (four-bit or eight-bit), the first few bytes of the speech file set up the
MSP53C691 to play the speech file at the proper speed for the synthesizer
algorithm. After the speech file is finished, the MSP53C691 goes back to run-
ning at 8 MIPS.
3.5.4.3
Test Mode
If the test mode is selected, data is transferred to and from the MSP53C691
(one nibble at a time). The MSP53C691 device receives one nibble of data and
then sets OUTRDY low, meaning that the MSP53C691 is ready to send data.
The MSP53C691 then sends the same nibble of data back to the
microcontroller. INRDY is then set low, meaning that the MSP53C691 is ready
to receive more data.
The following is a typical sequence of events for the test mode:
1) The MSP53C691 pulls INRDY low and waits for a command from the
master.
2) The master sends the command header 0x4 on the data bus. Note that
writing 0x4 to the data bus ensures that the DATA4 line is low, indicating
that the value on data lines DATA0–DATA3 is a command.
Most Significant
DATA LINES
DATA4
DATA3
DATA2
DATA1
DATA0
0
0
1
0
0
First command header sent
3) After receiving the header, the MSP53C691 pulls INRDY low again and
waits for a level 1 parameter from the master.
Содержание MSP53C691
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