- Published: Tuesday, 12 November 2013
- Written by Jon Chandler
- Hits: 9143
If you have a need to add a single sound effect to a micro project, a ISD1820 voice module board may be a good answer. These boards can record a single audio sample of up to 20 seconds using a built-in microphone and will play back the sample on demand with good fidelity. These are available on eBay for around US$6 and they're easily interfaced to a micro board. The ISD1820 chip can drive a small speaker directly or an amplifier may be used for higher volume levels.
Interfacing the ISD1820 is simple. There are two playback modes. The first is edge triggered; a positive pulse to the Playback-E pin triggers the module to play the entire message once. The second method, level triggered, will play the recording while it is high, and stop playing when it is low. Perhaps you want to have a low temperature alarm to monitor your pipes. Using the edge trigger, a pulse would cause the entire message to be played once: "Warning. Temperature is below freezing."
There is a slight complication in interfacing this to a 5 volt micro. The recommended operating voltage is 2.7v - 4.5v. 1N4148 diodes may be added between the mico and the Vcc and Playback-E pins on the IDS1820 board.
The only way to record audio into this module is via the microphone; there is no option to load data digitially. Recording is it simple though. Press the record button and speak or play a wave file through a speaker. Release the button and the sound is saved.
The ISD1820 chips are available for about a buck a piece on eBay and the circuit is pretty simple if you want to include the circuit on a board of your own design. The data sheet is available here. More information is available on the ElecFreaks website.
Only one complaint about this module...there are no mounting holes on the circuit board!