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Description of the Command Codes
3-22
Most Significant
DATA LINES
DATA4
DATA3
DATA2
DATA1
DATA0
1
X
X
X
X
First nibble sent
1
X
X
X
X
Second through X nibbles sent
Least Significant
1
X
X
X
X
Last nibble sent
16) Once all of the promised FM bytes has been sent, the MSP53C691 pulls
INRDY low again and waits for a command from the master. The master
can send a valid command to the MSP53C691 (if desired) or a dummy
command (0x00) if it has nothing else to send. If a valid command is to be
sent, the master must ensure that DATA4 line is low while sending the
command nibbles over the DATA0–DATA3 lines. When the MSP53C691
needs more FM data, it pulls OUTRDY low to let the master know the num-
ber of bytes of FM data requested, and the process is repeated.
17) After finishing sending the last nibble of FM data in the FM file, the master
can send some dummy data (0xFF) to the slave in response to each con-
secutive lowering of INRDY until the slave detects the end-of-FM file.
18) When the MSP53C691 detects the end-of-file, it pulls OUTRDY low. The
master then must read the data from the bus. OUTRDY goes low three
more times after that, sending a total of four nibbles (0, 0, 5, and 5) if the
speaking of the phrase was successful.
19) Then INRDY goes low again, indicating that the MSP53C691 is ready to
receive a new command.
3.5.4.5
Playing Mixed Mode in 4-Bit Transfer Mode
In mixed mode, the single-channel FM is played in the background and
CELP/MELP is spoken in the foreground.
The MSP53C691 can play mixed mode in four-bit transfer mode. This mode
also supports sending commands to perform other functions (volume control,
toggle I/O, etc.). The CELP/MELP and FM data is supplied to the MSP53C691
from the master over the four-bit data lines (DATA0–DATA3). The
DATA/COMMAND line is pulled high while transferring both the CELP/MELP
and the FM data. The master sends CELP/MELP data to the MSP53C691 by
default. The MSP53C691 sends a request back to the master (by pulling
OUTRDY low and transferring four nibbles to it) whenever it needs more FM
data. The master must then send a command (with parameter) back to the
MSP53C691, indicating how many bytes of FM data it is going to send. Then
the master can send the promised number of bytes to the MSP53C691 in
response to each lowering of INRDY, until the promised number of FM
data-bytes is sent. The following is a typical sequence of events for mixed
mode transfer:
1) The MSP53C691 pulls INRDY low and waits for a command from the
master.
Содержание MSP53C691
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