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Wednesday, 21 July 2010

Design of a Voice Recorder using ADC Microcontroller

The C8051F411 offers a versatile, small (5 x 5 mm), highly integrated, low-power solution for voice applications. The 12-bit ADC and DAC allow for reasonable quality sound at a 8 kHz sampling rate, and the hardware Accumulation and Burst Mode features of the ADC provide for further improvements with small processing tradeoffs. The Suspend mode operating feature allows the voice recorder to “sleep” while idle, saving power in a similar fashion to the traditional 8051 Stop mode, but still allows the recorder to wake and respond to the user without a hardware reset. This document describes the solution for a telephone-quality voice recorder using the C8051F411.

This document includes the following:
  • A description of the system hardware and software
  • Usage notes and customization considerations
  • A schematic, bill of materials, and detailed layout diagrams
  • The implementation of the software showing how to sample, compress, store, and play back a voice signal
Key Points:
  • Because of its small size, versatile peripherals, and low-power features, the ‘F411 readily lends itself to battery operated voice applications.
  • The system uses a DPCM (Differential Pulse Code Modulation) compression algorithm for data storage to extend the total recording time.
  • The recorder takes steps to minimize power usage while active and uses the “Suspend” feature of the ‘F411 to reduce power consumption when idle.


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