DT-1 Standalone Terminal
Aimed at users who wish to use D-STAR with their
transceiver without (also) having to connect a computer to it for operation,
the DT-1 Standalone Terminal is the next-up in features, complexity and cost.
The Standalone Terminal
is designed for use as a standalone messaging monitor, and contains a
variant of the DM-1 Smart Modem technology, combined with its own local
high-performance CPU, graphical LCD and keypad, thus eliminating the
need for a PC in several applications.
It can deal with various uses of
the D-STAR system, such as a repeater monitor, a short-message device,
but also as a data gateway into the D-STAR network. For easy messaging
functionality, a PS/2-style keyboard connection is available.
The prototype unit clearly shows the three boards that
make up the system. From bottom to top, we have:
-
CPU card. Two versions have been made; one runs with
a 16MHz AVR ATmega328 processor, for smaller systems, and another
variant was made containing 60MHz NXP LPC-2138 ARM processor, which
would allow almost any application to run on the system.
-
The modem board, which is just an embedded version of
the DM-1 Smart Modem. Embedded in this sense means, that it does not
have any USB or serial ports, power supply and so on, as all these are
provided by the CPU card. The prototype shown contains the older version
of the modem board, which still had the 25-pin D-SUB connector for the
radio side.
-
The LCD board, featuring a graphical LCD (128x64
pixels, various backlight colors available, blue shown) and a keypad
using standard pushbutton switches.
This early prototype worked well, but since has undergone
major redesigns, as the boards were based on an in-house standard size and
layout (standardized board modules, which allows for easy testing and
interconnecting of modules), and a new, more practical design had to be
done.
A more recent prototype is shown below. It was also used
as the control board for another (completely un-related but still
interesting) project, a controller for a Bosch KF163 mobile transceiver.
This version is already shaped for embedding in a nice
enclosure, and it shows the final keypad layout- which incidentally is also
very similar to the one designed for the DS-1 transceiver. No, that is not a
coincidence.
Most of the components are on the other side of the PCB.
The small board next to it handles the power supply, on/off switching logic
and power source selection, as well as a NiMH battery charger circuit and a
USB interface. In the final design of the DT-1, this "power board"
will be combined with the "modem board" to create a single second board to
connect to the display board, as the design requires the system to not be
too big for portable use.
Several design issues still exist, most of a mechanical
kind, and so it was decided to first finish the DM-1 design, so that could
be integrated into the DT-1 as a whole.