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Telephone answering machine design example

Description
The Telephone Answering Machine Design Example is a sophisticated telephone answering machine that provides everything commercial devices offer and more. Noteworthy features include improved voice quality and increased storage capacity over commercial machines. Additionally, Internet connectivity enables convenient messaging in the form of SMS messages or e-mails from anywhere in the world. Virtual answering machines can be set up for four different users. A user-friendly interface makes learning how to use this device and taking advantage of its many special features easy for anyone, regardless of their electronics savvy. The highly efficient system is designed around an LPC2138 microcontroller, which features an ARM7 RISC processor. Built with a small handful of components, the Telephone Answering Machine Design Example is cost-effective. The thoughtful inclusion of an external flash memory card and well-chosen algorithms for nearly unlimited storage capacity of crystal-clear messages contribute to the success of the design.

Block Diagram

Documentation

Products
Below are recommended microcontrollers for use in implementing a telephone answering machine.

Comparison Table

Product Pins On-Chip
Flash
On-Chip
RAM
Comments
LPC2138 64 512KB 32KB Base microcontroller used in the design example.
LPC2136 64 256KB 32KB A lower-cost microcontroller with the same amount of on-chip RAM but with only half the on-chip flash memory.
LPC2146 64 256KB 32KB
+ 8KB
An upgraded microcontroller with a USB interface. USB could be used instead of Ethernet to connect to a PC if Internet functionality is not desired.

MCUs

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 LPC2136 Microcontroller with 256KB ISP/IAP flash, 2x10-bit ADC, DAC
 LPC2138 Microcontroller with 512KB ISP/IAP flash, 2x10-bit ADC, DAC
LPC2138FBD64LQFP-64DiscontinuedSOT314-2Pb-FreeMSL=1
LPC2138FBD64/01LQFP-64ProductionSOT314-2Pb-Free        
LPC2138FHN64HVQFN-64DiscontinuedSOT804-2Pb-FreeMSL=3
LPC2138FHN64/01HVQFN-64ProductionSOT804-2Pb-Free        
Family Functions Literature Models Support Docs Tools Consultants Price Buy Online More...
 LPC2146 Microcontroller with USB 2.0 full-speed device, 256KB ISP/IAP flash, 2x10-bit ADC, DAC
More Information

Images


Working Prototype

Circuit Blocks

Answer Flow

Schematics

Example Code

Bill of Materials

Disclaimer

This design example shows possible hardware and software techniques used to implement the design. It is imperative that the viewer use sound engineering judgment in determining the fitness of this design example for any particular application. This design example may include information from 3rd parties and/or information which may require further licensing or otherwise. Additional hardware or software design may be required. NXP Semiconductors does not support or warrant this information for any purpose other than an informational design example.
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