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Sequence of Command Codes and Data Streams
3-4
-
Command header 6—Adjust volume
-
Command header 7—Return status of data buffers
-
Command header 8—Initiate sleep mode
-
Command header 9—Receive FM data (while speaking in FM only or in
mix mode)
-
Command header A—Perform speed/pitch shift
-
Command header B—Set up oscillator
The command headers are sent to the MSP53C691 in four-bit nibbles with a
0 in the DATA4 line in either four-bit or eight-bit mode.
CAUTION
Support for sending commands while speaking is not available in
eight-bit mode. In eight-bit mode, commands can be sent to the slave
between speaking phrases.
3.3.2
Parameters
For the command codes, there are two types of parameters that are sent to
the MSP53C691 after sending the command header: level 1 and, if required,
level 2. Level 1 and level 2 are levels of command information that further
defines the command code. For example, if the command header is
Adjust the
Volume (one nibble command code 0x6), then the level 1 parameter (one
nibble, 0x1 through 0x6) defines what level the volume is being set to (that is,
low, medium, or high). Also, if the command header is
Configure Internal
Registers (one nibble command code 0x1), then the level 1 parameter defines
which internal register address to write to (two nibbles specifying the address
of the register). The level 2 parameter is the data written to the internal register
(four nibbles specifying the word to be written in the register). All the command
headers and Level 1 and level 2 parameters are sent to the MSP53C691 a
nibble at a time with the DATA4 (DATA/COMMAND) bit set low. While
interleaving commands between speech data, it is advisable to send all the
nibbles of the command (command header, level 1, and level 2 parameters,
if applicable) before sending more speech data or commands. Refer to
Table 3–1,
Command Codes, for additional information.
3.3.3
Return Values
The MSP53C691 can return values to the microcontroller when required. The
MSP53C691 sends return values to the master either to respond to a com-
mand, to return error codes, or to provide its current status. The values re-
turned vary in content, depending on the command code initiated and on the
status of the MSP53C691. The following is a list of returned values from the
MSP53C691:
Summary of Contents for MSP53C691
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