Issue
146 September 2002
Internet
Enabling Made Easy
by
Fred Eady
APPLYING THE
2124
Now you know how
to use the 2124 modem as a stand-alone e-mail generator.
By introducing you to Press4Service, I’ve saved you
enough money to buy that Gulfstream V and a set of lures.
If you’re not the corporate type and need to do some
tricks with the CH2124, the 2124 modem is just as easy
to deploy with your favorite microcontroller.
Most 2124 modem
applications can be effective with only the resources
provided by the 2124 modem. There will be applications
that require an e-mail to be sent that is relative to
more external variables than the 2124 modem can handle
natively.
For instance, let’s
suppose you’re monitoring door and window activity in
a security application. Rather than place a 2124 modem
at every door and window that you want to secure, sensors
are mounted at each desired location. The external microcontroller
is programmed to scan the door and window intrusion
sensors. E-mail is sent immediately that details which
sensor was triggered. Because of the high level of integration
found in the iNet@T command set, this design can be
easily implemented.
When a sensor triggers,
the external microcontroller, using its software of
hardware UART, issues iNet@T commands directly to the
2124 modem. These iNet@T command strings are built dynamically
by the external microcontroller depending on the door
and window sensor input. For instance, each door and
window could be identified by a name that’s associated
with a sensor input bit on the external microcontroller.
Assume at this point
that the ISP phone number, login name, login password,
e-mail passwords, as well as the e-mail From:, To:,
and Subject: fields within the 2124 modem were initialized
when this modem node was installed. Note that with that
information already loaded, the external microcontroller
only has to send two iNet@T commands to the 2124 modem
to dispatch the e-mail message.
The first iNet@T
command would load the dynamically created e-mail message
into the 2124 modem’s flash memory. The second command
would send the e-mail. Using a Custom Computer Services
PIC C compiler, I’ve coded a simple example that uses
a PIC16F876 as the external microcontroller (see
Listing 1). Although the example code works, you’ll
want to add code to check the 2124 modem’s progress
and respond to its messages in a real application.
