How to interface modems with ATMega64 micros?

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Hello

I have two circuit (include two ATmega64 micros) at 6Km located apart from each other,Can I connect them (for send data) by external cable modem (these modem is used for dialup connection by PC)? If yes,how I can interface to modems ?Is it needed to use AT command ? How I can find AT command for modems?
 

atmel modem

Hello brother!

For resolve Your problem, that are some alternatives.

I_ UHF radio with fsk "modem"

II_ PSTN (Public Switched Telephone Network)

III_ 485 network with some "repeaters"

IV_ GSM/GPRS Modens

I think the most simple solution are II because are lot of "embedded" modens for this specific implamentation.
For more information about these modens, visit the cml micro website and get more information (AT Commands, hardware interface, etc).

Gorkin
 

Re: modem interface

Can I use the modems that are used for PCs(connected to COM1 or COM2) ?

Do they support AT Command?
 

Re: modem interface

hi ,

yes you can use external modems with AT commands , you can find them by search in google .

regards.
 

modem interface

first you must initials your modem with correct at command.
most of at command for varius modem are similar.
next use print and input commant with bascom avr for connection and data SEND.
 

Re: modem interface

is there a code to show interfacing procedure to external modems(using AVR ,..)?
 

Re: modem interface

For analog PSTN modens, have two options:
1º: Serial interface - RS232 "physical pattern"
2º: Parallel interface - TTL "physical pattern"

For the first option, do You need build one interface for conect the microcontroller/modem. In second option, if Your microcontroller are powered with 5 volts, no additional interface are needed.

Gorkin
 

modem interface

Talking to a PC-Modem is the same as talking to any other RS232 device. Make sure you have Max232 or equal on the Mega64 for doing the RS232 interfacing.

You will probably need to interface the following signals:

Atmel Modem
TX - TX
RX - RX
PINx - DCD (Modem outputs 1 when connected to other modem , so input on AVR , via Max232)
PORTx - DTR (Avr output via Max232 , resets modem , when going low)

Then connect Modem RTS to Modem CTS , and don't use hardware handshake , or you will need to interface RTS/CTS via another Max232

For modem commands "google" for "Modem AT Commands"
/Bingo
 

modem interface

use AT commond whit MAX 232 interface
 

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