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Interfacing a microcontroller with a modem

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matt_d82

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I am working on a project in which a microcontroller needs to transfer data to a computer over a modem and telephone line. I will be using a microcontroller that has a built-in UART (8051 family, AT89S53). I am looking for the easiest way to do this.

I don't know much about serial communications and I don't have a lot of time to learn it. I was hoping it would as easy as connecting a few lines between the microcontroller and the modem. Then just sending modem commands (AT commands) and data over the microcontrollers UART to the modem, and have everything else know what to do.

Does anyone know of a very simple modem IC to do the job? Even using a regular external modem may do the trick. I've seen a few "modem" ICs but they have like 40+ pins. I was hoping for something much simpler. Is there some other easier way to accomplish this? Does anyone know of any good tutorials or other information on interfacing a microcontroller with a modem IC?


Thanks!

Matt
 
matt_d82 said:
I am working on a project in which a microcontroller needs to transfer data to a computer over a modem and telephone line. I will be using a microcontroller that has a built-in UART (8051 family, AT89S53). I am looking for the easiest way to do this.

I don't know much about serial communications and I don't have a lot of time to learn it. I was hoping it would as easy as connecting a few lines between the microcontroller and the modem. Then just sending modem commands (AT commands) and data over the microcontrollers UART to the modem, and have everything else know what to do.

Does anyone know of a very simple modem IC to do the job? Even using a regular external modem may do the trick. I've seen a few "modem" ICs but they have like 40+ pins. I was hoping for something much simpler. Is there some other easier way to accomplish this? Does anyone know of any good tutorials or other information on interfacing a microcontroller with a modem IC?

Just use an external computer modem - all you need to provide it with is RS232 serial data, a MAX232 will interface from your processor, and you just need to write the software to communicate over the RS232 link.

It couldn't get any simpler, if you try and control a modem IC directly, it would be many, many times more complicated - an external modem already includes a micro-processor, which does all the hard work for you!.
 
Hi Matt:

Don't know where you live, but I have successfully used Multitech embedded modems (www.multitech.com). They have a whole selection of modems with different price/preformance (mostly speed) ratios. I typically use their 2400 Baud modem because it is cheap ($25 approx.), and I do not not need high speed anyway for my embedded applications.

Initialization is quite simple. Typically you just send a single initialization string consisting of some AT, &S, and &W commands.

Hope that helps!

Jem
 
I am working on similar project, I have not started yet but I think you can try the At commands using hyper terminal on an external modem before using microcontroller and max232. i would licke to check the transfer rate between PC and modem
 
Hi Matt:

Don't know where you live, but I have successfully used Multitech embedded modems (www.multitech.com). They have a whole selection of modems with different price/preformance (mostly speed) ratios. I typically use their 2400 Baud modem because it is cheap ($25 approx.), and I do not not need high speed anyway for my embedded applications.

Initialization is quite simple. Typically you just send a single initialization string consisting of some AT, &S, and &W commands.

Hope that helps!

Jem

Jem,

This sound like it might be better than the external modem idea. Does the embedded modem connect direct to the uC at 5 volts or do you still need voltage level converting and inverting to communicate with it?
 
microcontroller interface modem

I am presently working on the interfacing of the pic micro controller to the wireless modem. I am using a pic24fj256gb110, I am thinking of using mc35i modem. this is having RS232 interface but my pic gives me output through
RJ45 is it possible to connect this pic to the modem
 
The person "Jem" that you are conversing with, seems to have disappeared more than 5 years ago.
 
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