ISD1740AX Просмотр технического описания (PDF) - Winbond

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ISD1740AX

Multi-Message Single-Chip Voice Record & Playback Devices

Winbond 

ISD1700A SERIES

7 PUSH-BUTTON OPERATIONS

The user utilizes the REC , PLAY , FT , FWD , ERASE , VOL or RESET pin to initiate an operation.

The device automatically enters the power-down state at the end of a PLAY, REC, ERASE, FWD,

VOL, or RESET operation.

7.1 OPERATION OVERVIEW

After power-on-reset (POR), the device is in the factory default state and two internal record and

playback pointers are initialized. (Detailed information about these two pointers is provided later in

this Section.) Then, the active analog path configuration is determined by the state of the FT , and

by the operation requested (e.g. record, playback, or power down).

Up to four optional sound effects (SE1-4) can be programmed into the device to provide audible

feedback to alert the user about the operating status. Separately, the LED output provides visual

feedback on the operating state even if no sound effects are programmed.

A circular message management technique is implemented. Recorded messages are stored

sequentially into the memory from the beginning to the end in a circular manner.

Two internal pointers, the record pointer and playback pointer, determine the point at which an

operation starts. After power-on or RESET , these pointers are initialized as follows:

• If no messages are present, both point to the beginning.

• If messages are present, the record pointer points to the next available memory location after

the last message and the playback pointer points to the beginning of the last recorded

message.

The playback pointer is affected primarily by the FWD operation. The record pointer is updated to

the next available memory location after each REC operation.

7.1.1 Record Operation

Recording is controlled by the REC . Setting this pin Low starts a record operation. The

device will start recording from the next available location in memory and will continue

recording until either the REC is returned High or the memory becomes full. The source of

the recording is from either MIC or AnaIn, whereas the active analog configuration path is

determined by the desired operation and the state of the FT . The REC is debounced

internally. After recording, the record pointer will move from the last recorded message to the

next available address and the playback pointer will be positioned at the beginning of the

newly recorded message.

It is important for an Erase operation to be performed on the desired location before any

recording proceeds. Also, the power supply must remain On during the entire process of

recording. If power is interrupted during recording, the LED will blink seven times, which

indicates that something unusual has occurred. In this event, performing a Global Erase will

reset the chip back to its proper state.

Confidential

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Publication Release Date: March 28, 2005

Revision A0

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