Message Recorder Digital Electronics Project

Introduction
The purpose of this digital electronics project is to record messages using a dedicated voice recorder integrated circuit. Recordings are stored in a non volatile memory cells, which means that the message will still be saved even though power has been removed from the device.
Winbond’s ISD2500 Series provide high-quality, single-chip, Record/Playback solutions for 60 seconds to 120 seconds message applications. The CMOS devices include an on-chip oscillator, microphone preamplifier, automatic gain control, antialiasing filter, smoothing filter, speaker amplifier, and high density multi-level storage array. In addition, the ISD2500 is microcontroller compatible, allowing complex messaging and addressing to be achieved. Recordings are stored into on-chip nonvolatile memory cells.


Circuit Description

The ISD25120 has several modes of operation. The mode used here is as a multi-message recorder. You may record as many messages as you want up to 120 seconds of memory space. Put the SPDT switch into the Record position and just push & release the Start/Pause button to start recording. The Record LED goes on. Push the Start/Pause button to Pause - stop recording. That is the end of Message 1. Sometime later you can record a follow on message, Message 2, by pushing the Start/Pause button again. When you put the switch to Play the messageswill playback. Only one message will be played back at a time. You must push Start/Pause again to get the next message. The Reset switch will move the internal address pointer back to the start of the memory space.