Sennetech Improved Digital Answering Machine System ECE 480 TEAM 13 Sponsor: Jim Senneker, Sennetech Inc. Facilitator: Nihar Mahapatra Manager: Mark Magee Web Manager: Kathryn Revitte Lab Coordinator: Nuncio DeCia Document Preparation: Trevor Peterson
ECE 480 TEAM 13
Sponsor: Jim Senneker, Sennetech Inc. Facilitator: Nihar Mahapatra
Manager: Mark Magee
Web Manager: Kathryn Revitte
Lab Coordinator: Nuncio DeCia
Document Preparation: Trevor Peterson
Presentation Coordinator: Stas Todromovich
The purpose of this project is to research and develop a digital answering machine system with high sound quality and the ability to shuttle backwards and forwards during message playback. Other unique features of our system include the LCD touch screen user interface and the improved sound quality.
We would like to give a special thanks to Jim Senneker of Sennetech for his help and the opportunity to design something creative and new.
LCD Graphical Touch-screen $279.00
LCD Touch-screen Interface Board $30.00
PIC18F4550 Microcontroller $11.43
ISD 1110 Voice IC Chipcorder $5.64
ISD 2560 Voice IC Chipcorder $10.49
Cermetek CH1837 DAA $31.70
NE5532 Low Noise Op-Amp $1.68
MCP41100 Digital Potentiometer $1.78
AC-DC Wall Transformer $21.95
Telephone Cables and Connectors $14.24
Problem/Need: For a digital answering machine with improved sound quality and the ability to shuttle back and forth within a message.
Intended user/usage: The intended user is the average person with a land phone line either at home or an office. The intended usage is to receive telephone messages.
Assumptions/Limitations: Our main limitation was the unavailability of memory greater than 8MB available in DIP packages. We assume that in production, the memory size can be increased.
Design objectives: To detect rings and answer the phone, record messages, play back recorded messages, shuttle messages during playback, record and play an outgoing message, and detect handset pickup.
Design constraints: Design should use low power, output high quality audio, and have an easy to use graphical user interface.
The digital answering machine we have designed is built around the PIC18F4520 microcontroller, which controls the other components. The LCD touch screen contains the graphical user interface with which users can control the answering machine. It is programmed in HTML and uses the PIC’s USART protocol to send and receive information from the PIC. The PIC also interfaces with the chipcorder ICs to play and manipulate messages. The other components of our design are the class A-B push-pull audio amplifier, the speaker, the microphone and the microphone preamplifier.
Our final product is a working answering machine which can answer the phone, play an outgoing message, record a message, play back a message, and allows shuttling forward and backward during playback.
Final Product/Project Results:
Our design can perform most functions of an answering machine: answering the phone, playing an outgoing message, and recording incoming messages. In addition, it has the added functionality of shuttling back and forward. However, it can hold only four 15-second messages. Future improvements would be increasing memory size, adding USB functions, time/date stamping, and marking messages.
Testing was done by connecting the unit to a phone line, calling the line, debugging the code, and listening to the audio quality. Changes were made to the design and code based on these tests.