dear sir; i want to use a 8051 for sending data through phone line , i want a idea about how design it and how write a program for it please guide me best regards javad majd
This is not a trivial problem. Consider: How much data do you want to send in each direction? How fast do you need the data to be sent? Do you need to initiate a call, pick up a call or both? How much do you want to spend on the hardware? With this information you should be able to choose between the following: a) Off-the-shelf stand-alone, full featured modem. b) Built-in full featured modem. c) Built-in limited features modem. d) Bespoke tone generator/decoder. e) DTMF generator/decoder. f) Something else.
One very important thing Graham omitted: What are the LEGAL and/or regulatory requirements in your territory? http://www.8052.com/forum/read.phtml?id=36214 For embedded modem modules, look here: http://www.multitech.co.uk/PRODUCTS/~Modems/Embedded/