Re: Using Cell-Phone as Modem to Xmit Data From Remote non-Windows Devices ?
- From: mmm <mmm@xxxxxxxx>
- Date: Tue, 02 Jan 2007 18:07:48 +0100
Luminoso wrote:
On Tue, 02 Jan 2007 17:00:01 +0100, mmm <mmm@xxxxxxxx> wrote:
Luminoso wrote:
I need to use cell phones to return remote data from envionmental monitors. The monitors will NOT be running
Windows or Linux or any OS (they're PIC-based). The idea
is to use the cheapest, dumbest possible cell phone with
a serial or USB plug as the modem.
Dial-out can be done by programming the proper commands
into the PIC - assuming the manufacturer uses an 'AT' command set or something similar. Dial-IN would be nice,
if the phone produces some signal on its buss that can tell
the microcontroller "I'm getting a call - turn on and send
your data". If I could dial to the devices, a good old
program like PROCOMM would serve to collect the data.
Internet capability is NOT needed or desired. Even a 300 baud
connection would serve my purposes. The devices won't be
collecting THAT much data each day. Even ten seconds at 300
baud would do it - and I wouldn't have to pay for internet
access.
I've looked around on the web but there's a serious lack of
focused "how to" articles on this subject. I can't tell if
there's a specific kind of phone I need, CMDA, GSM or whatever.
Everything I see assumes you're using a Winders or Mac to operate
the modem.
Has anyone come across phone-modem stuff more appropriate for
low-end embedded applications ? Money IS an issue here, power
consumption IS an issue. I'm not going to bolt an old Winders
laptop to 30 remote sensing stations just so I can make the
phone work. A PIC, some sensors, a battery, a solar cell, a
dirt-cheap cell phone ... that's the very basic package I'm
trying to create.
we have worked with a siemens GSM cell , if I remeber well it was a T35 or something similar, mostly identical to the standard part but in a rugged enclosure it work as a 'standard hayes' modem in data mode ( with some extension in AT commands for system management )
the cell is actually connected to a data acquisition station and we are able to talk to him trough the hyperterminal
here in Italy the only problem was ( is ? ) the use of a special contract from the cellular operator, not the standard voice contract but a 'data contract'
My throughput needs are SO small that GSM is not
required. Ordinary voice-quality transmission
ought to be adequate. As I said, even 300 baud
is plenty quick. I'd be downloading about 100
bytes twice a day from each station.
But I need to find someone who's made it all WORK
before. I don't know enough about cell phones or
moving data over them.
the module that I am talking about have a 'standard' RS-232 connection you only need to connect to your device and insert the SIM ( perhaps you need to do some configuration trough AT commands before first real use)
the real name of this cell-module could be TC35
.
Any pointers or links will be greatly appreciated.
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