Authors : K. Y. Rokde1, Dr. P.B.Dahikar2 , S.S.Shende 3 , Dr.M.J.Hedau4
Page Nos : 302 to 306
Description :
The paper is about for the device control system with telephone
answering machine using Embedded technology. In this work, the incoming signal is
detected by ring detector block which uses opto-coupler for line isolation. MCT2E optocoupler
is used for this work. DTMF detection and decoding is provided by DTMF
decoder block. An IC MT 8870 is a complete DTMF receiver, which is able to detect and
decode all 16 DTMF tone pairs into a 4-bit code.
A two-wire serial EEPROM (AT24C02) is used in this to retain the password, the
relay status and the number of rings to which the system should respond. Data stored
remains in the memory even after power failure, as the memory ensures reading of the
latest saved settings by the micro controller. This 12 C bus compatible- 2048-bit (2-
kbit) EEPROM is organized as 256x8 bits. It can retain data for more than ten years.
Using just two lines (SCL and SDA) of the memory, the microcontroller can read and
write the data corresponding to the data required to be stored.
Keywords: DTMF, Telephone answering machine, Embedded system,
microcontroller.
