NSAM266SAASLASHV datasheet(24/52 Pages) NSC

24 / 52 page

20 Software (Continued)

23 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 (eg 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

24) 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 22 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

24 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 (eg 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

(eg 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-

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 214

25 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 214 describes the TUNE command

26 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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