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I want to transfer data from a pc to mcu with a modem

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Advanced Member level 1
Jun 5, 2001
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I would like to transfer data from a pc to a mcu in a distance by a telephone line.
the first solution i think is a modem can u help me?
the second solution is internet but i think it is difficult..

thx for listening



You have few option as you say :

One connect to internet , is nice you can control the system from
any comp, but high cost second problem
you need also to pay to internet supplier and you can call to module if
it not connected itself to internet.
and also need know the internet protocols.

Second way to use a modem module it ok
you have simple interface rs232 and at command easy to use.

some oem modem links:
**broken link removed**
**broken link removed**

Of corse you have also wirelles modems from gsm/tdma line telephones

Thrid option is only for low speed and controls, to use tone generotors chips like at phone, from transmit few data and commans.

Best regards. 8)

that depends on the modem you use


What ever modem you use see its manual , for commands.
Now use a null modem connection between the modem and PC then wire and after that your Microcontroller .I did long time back , you have to implement a protocol stack / driver for the modem and it is not that difficult , I think it is 1/100 th of the effort require to implement a Bluetooth driver :roll:


for some mcu there are basic internet protocol (UDP and PPP) and modem control code free.
For example for mo*otorola H*C*0*8, there is an aplliction note reporting all a project to communicate by internet with the mcu.

Using a modem is not as difficult as it first seems. A little effor can result in easy connection. Use a good external modem which has error correction feature built in. You will need a serial port on MCU to connect to the serial port of the modem.

Initialialze the mode as send("ATE0\\J0\\N3\\Q0\\V4%C1\r\n"); actual commands for a modem might differ.

you can dial a number suing ATDT1234567890 command
the modem sends a "RING" string when a bell rings
you can pickup line by issuing ATA command
you can disconnect using ATH0 command
the modem sends a "CONNECT 9600....." when connection established.
after that you can send and recive data just like a direct serial port conenction


controll GSM modem is different general modem

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