Hai,

I want to build modem 1200bps base on 89C52. I know there's a lot chip that we can buy in the market (etc. TCM3105). But there's anyone know to build using 8051 program ? I want to build the modem based bell-202 standard (1200 bps outgoing and 1200bps half duplex). the frequency for '0' data signal is 1200 HZ and '1' data signal is 2200Hz.I got trouble in 2200Hz to match it with 1200 HZ.

Thanx