MT8843 Calling ID

[dramrattan]

Hi,

Could anyone explain to me how to receive caller ID using this chip connected to the telephone. I am trying to be able to explain it by morning for my demonstration. I know the ringing is received between the first and second rings but how is this calling information decoded by this chip and sent to a PIC18F452? Any info that coud help me understand how caller ID works and how to decode it in order to send to a PIC18F452 would be very very very much appreciated.

 

[crutschow]

Have you looked at the block diagram and read the information in the MT8843 data sheet?

Caller ID works by sending caller information during the interval between rings in FSK (frequency shift keying) format with the two signal frequencies being 2130Hz and 2750Hz. The chip senses this signal and decodes it into digital 8-bit word serial format at the DATA output line to send to the PIC, synchronized by the Data Clock (DCLK) and Not Data Ready (/DR) lines.