isd1740a Winbond Electronics Corp America, isd1740a Datasheet - Page 13

• Manufacturer Part Number: isd1740a
• Description: Multi-message Single-chip Voice Record&playback Devices
• Manufacturer: Winbond Electronics Corp America

7 PUSH-BUTTON OPERATIONS
The user utilizes the
The device automatically enters the power-down state at the end of a PLAY, REC, ERASE, FWD,
VOL, or RESET operation.
Confidential
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
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
The playback pointer is affected primarily by the
the next available memory location after each
7.1 O
x
x
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.
7.1.1
Recording is controlled by the
device will start recording from the next available location in memory and will continue
recording until either the
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
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.
PERATION
Record Operation
O
REC
VERVIEW
,
PLAY
,
REC
FT
RESET
,
is returned High or the memory becomes full. The source of
FWD
REC
, these pointers are initialized as follows:
. Setting this pin Low starts a record operation. The
,
ERASE
REC
- 13 -
FWD
operation.
,
VOL
operation. The record pointer is updated to
or
Publication Release Date: March 28, 2005
RESET
ISD1700A SERIES
FT
pin to initiate an operation.
. The
REC
is debounced
Revision A0
FT
, and