NSAM266SA Datasheet, PDF (24/52 Pages) National Semiconductor (TI) – NSAM266SA CompactSPEECHTM Digital Speech Processor with Serial Flash Interface

2 0 Software (Continued)
2 3 THE STATE MACHINE
The CompactSPEECH functions as a state machine It
changes state either in response to a command sent by the
microcontroller after execution of the command is complet-
ed or as a result of an internal event (e g memory full or
power failure)
The CompactSPEECH may be in one of the following
states
RESET
The CompactSPEECH is initialized to this state after a full
hardware reset by the RESET signal (see Section 1-6)
CompactSPEECH detectors (VOX call progress tones and
DTMF tones) are not active In all other states the detec-
tors are active (See the SDET and RDET commands for
further details)
IDLE
This is the state from which most commands are executed
As soon as a command and all its parameters are received
the CompactSPEECH starts executing the command
PLAY
In this state a message is decompressed and played back
RECORD
In this state a message is compressed and recorded into
the message memory
SYNTHESIS
An individual word or a sentence is synthesized from an
external vocabulary
TONE GENERATE
The CompactSPEECH generates single or DTMF tones
MEMORY READ
The CompactSPEECH reads a 32-byte block from the mes-
sage memory and sends it to the external microcontroller
MEMORY WRITE
The CompactSPEECH accepts a 32-byte block from the ex-
ternal microcontroller and writes it to the message memory
After receiving an asynchronous command (see Section
2 4) such as P (Playback) R (Record) SW (Say Words) or
GT (Generate Tone) the CompactSPEECH switches to the
appropriate state and executes the command until it is com-
pleted or an S (Stop) or PA (Pause) command is received
from the microcontroller
When an asynchronous command execution is completed
the EV NORMAL END event is set and the Compact-
SPEECH switches to the IDLE state
Section 2 2 provides a table which shows all the Compact-
SPEECH commands the source states in which these com-
mands are valid and the result states which the Compact-
SPEECH enters as a result of the command
2 4 COMMAND EXECUTION
A CompactSPEECH command is represented by an 8-bit
opcode Some commands have parameters and some
have return values Commands are either synchronous or
asynchronous
SYNCHRONOUS COMMANDS
A synchronous command must complete execution before
the microcontroller can send a new command (e g GMS
GEW)
A command sequence starts when the microcontroller
sends an 8-bit opcode to the CompactSPEECH followed by
the command’s parameters (if any)
The CompactSPEECH executes the command and if re-
quired transmits a return value to the microcontroller Upon
completion the CompactSPEECH notifies the microcontrol-
ler that it is ready to accept a new command
ASYNCHRONOUS COMMANDS
An asynchronous command starts execution in the back-
ground and notifies the microcontroller which can send
more commands while the current command is still running
(e g R P)
STATUS WORD
The 16-bit status word indicates events that occur during
normal operation The CompactSPEECH activates the
MWRQST signal to indicate a change in the status word
This signal remains active until the CompactSPEECH re-
ceives a GSW command
ERROR WORD
The 16-bit error word indicates errors that occurred during
execution of the last command If an error is detected the
command is not processed the EV ERROR bit in the
status word is set to 1 and the MWRQST signal is activat-
ed
ERROR HANDLING
When the microcontroller detects that the MWRQST signal
is active it should issue the GSW (Get Status Word) com-
mand which deactivates the MWRQST signal Then it
should test the EV ERROR bit in the status word and if it
is set send the GEW (Get Error Word) command to read
the error word for details of the error
For a detailed description of each of the CompactSPEECH
commands see Section 2 14
2 5 TUNABLE PARAMETERS
The CompactSPEECH processor can be adjusted to your
system’s requirements For this purpose the Compact-
SPEECH supports a set of tunable parameters which are
set to their default values after reset and can be later modi-
fied with the TUNE command By tuning these parameters
you can control various aspects of the CompactSPEECH’s
operation such as silence compression tone detection no-
energy detection etc
Table 2-2 describes all the tunable parameters in detail
Section 2 14 describes the TUNE command
2 6 MESSAGES
The CompactSPEECH message manager supports a wide
range of applications which require different levels of DAM
functionality
The message-organization scheme and the message tag
support advanced memory-organization features such as
multiple OutGoing Messages (OGMs) mailboxes and the
ability to distinguish between InComing Messages (ICMs)
and OGMs
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