NSAM265SRA datasheet(6/58 Pages) NSC

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10 Theory of Operation (Continued)

TABLE 1-1 CompactSPEECH States and Transitions

(Continued)

Command

Description

Source State

Result State

Message Management Commands

CMT

Cut Message Tail

IDLE

Delete Message

IDLE

DMS

Delete Messages

IDLE

Get Length

IDLE

GMT

Get Message Tag

IDLE

GNM

Get Number of Messages

IDLE

GTM

Get Tagged Message

IDLE

RRAM

Read RAM

IDLE MEMORY

READ

MEMORY

READ

SMT

Set Message Tag

IDLE

WRAM

Write RAM

IDLE MEMORY

WRITE

MEMORY

WRITE

Command is valid in IDLE state but has no effect

13 COMMAND EXECUTION

A CompactSPEECH command is represented by an 8-bit

opcode Some commands have parameters and some

have a return value Commands are either synchronous or

asynchronous

Synchronous Commands

A synchronous command completes 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)

The Status Word

The CompactSPEECH processor has a 16-bit status word

to indicate events that occur during normal operation The

CompactSPEECH activates the MWRQST signal to indi-

cate a change in the status word This signal remains active

until the CompactSPEECH receives a GSW command

The 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 30

14 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 3-1 describes all the tunable parameters in detail

Section 3 describes the TUNE command

15 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

The NSAM265SF can store up to 256 messages per 4 Mbits

of AFLASH storage The NSAM265SR can store up to 100

messages per 4 Mbits of ARAM storage

A message is the basic unit on which most of the Compact-

SPEECH commands operate A CompactSPEECH mes-

sage stored in ARAM or AFLASH can be regarded as a

computer file stored on a mass-storage device

A message is created with either the R or the WRAM (Write

RAM) command When a message is created it is assigned

a time-and-day stamp and a message tag which can be

read by the microcontroller

The R command takes voice samples from the codec com-

presses them and stores them in the message memory

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