I am looking for for documents to describe communication to a modem and I to interface a modem to a 8051 mcu (DTR, CTS ...) is there any application notes on that subject.
i want to interface 809c51 to telephon line
Suggest that you go to SiLabs.com and search for their Si2404 chip data. All AT commands and responses are detailed. It's a good modem chip to interface to a C51 chip either via parallel port or serial port. Bradford
Or take a look at SocketModems: http://www.multitech.com/PRODUCTS/Categories/Embedded/