The Mini-HotSpot Board
Almost two years after its introduction, the most popular board
still is our Mini-Hotspot board. Initially designed to only handle
Simplex links (we simplified the original dual-processor design
based on the assumption that most people would not need the second
processor for repeater mode) so we could have a smaller board, the
current firmware happily handles Duplex mode on this board
With the new DUTCH*Star HSA designed and almost ready for production, we
did not expect customers to still order this board... but they do, and
they do it a lot!
So, much to our own surprise, we proudly present the new version of
our Mini-Hotspot board, the "Revision C", also known as the "Blue
Not many things have changed since we updated the original board to fix
some initial errors, and added D-COS. We made the board a little
smaller after we cleaned up the placement of parts, for example. The
most important change in this revision is, that it is now operating in
the so-called "V5" mode, which means that it does forward the RSSI
information from the modem chip to the processor chip, which
subsequently can send it to the PC for further usage.
If you'd like to know more about it, you can download the
schematics here, which also includes the BOM (Bill Of Materials, also known as the
Parts List) and the parts placement drawing.
The PCB production files are available for those who want to make a board for
themselves and/or some friends. Send us an email and let us know what
you want to do, and we will try to help you out!
Construction and Reference Manual (version 2.00) describes
how to build your board into a working Mini-HotSpot system. It also
contains a parts list in case you want to buy your own parts, as well as
a detailed parts placement drawing so you can easily what-goes-where.
You can order this board, a complete parts kit and
even a ready-to-use built&tested unit in our Web Shop.
which is also the place to go to order our firmware for it if no
ready-to-use unit is needed. A pre-made Radio Cable is
also available, this cable will connect the board to most modern
transceivers that feature a PS/2-style ("MiniDIN-6") port labeled
"data", "packet" or "tnc".
The people at the
GMSK_DV_NODE group will be more than happy to help you with any problems you
might run into- after all, it is the same board that is run by many
others on that group.
Back in 2009, when the GMSK Node Adapter was introduced, the
Mini-Hotspot board also started its history. Below are some older
announcements regarding this board and its various incarnations.
If you don't need the standalone repeater mode (which is the
case if you use the board with the HotSpot software), then you can use the
new Mini-HotSpot board, which simply is a smaller, trimmed-down version
of the original Node Adapter design. It does not have the second
processor and its supporting circuits, and, therefore, cannot be used in
Designed by Mark Phillips G7LTT, the
original Mini-HotSpot PCB only measured 2.5 x 2.75 inches, and
ran the original Version 4.XX family of firmware, written by Satoshi
Yasuda JK1ZRW. It is no longer being offered for sale as the PCB had some design errors.
A direct result from the co-operation between Mark and Fred van Kempen PA4YBR,
the new version of the Mini-HotSpot board is a little larger than the original
version (3.6 x 2.1 inches) and now uses a somewhat cleaner placement of the
various LED's, jumpers and connectors, at the cost of a board that is slightly
After some discussion on the Yahoo! group, it was
requested that Andy G4ZSM's Digital COS circuit be added
to our board. This circuit uses the RSSI value generated by the CMX589A
modem chip to determine if there is a valid signal being received or not,
and this result is then used as a COS signal to the board.
Especially with systems that have to deal with both
analog (FM Voice) as well as digital (GMSK D-STAR) signals, using the
GMSK quality indicator gives better results for determining whether to
enter analog or digital mode. Dual-mode repeaters will obviously
benefit from this !
The new Mini-HotSpot PCB with the
Digital COS added to it (and some other minor cleanups, as set out
for Rev.A01.) You can see the extra RSSI LED's (the yellow ones)..
during reception, these LEDs will indicate the relative signal strength.
If the signal strength exceeds a level set by the user, the circuit will
raise the COS line, and the green LED will light, indicating we have a
valid signal at hand.
This signal adds another jumper switch (SW2);
it selects between Analog COS (the signal from the radio, polarity being
selected by SW1 and SW3) or Digital COS, which is our new signal.
All this fun obviously requires space on the PCB, so
we had to make it a little larger. Not a lot, only about 10mm or so; its
length remained the same. We could have muddled with smaller trimpots,
but to keep things clean and simple, we decided to just make the board
larger- this also allowed us to place the extra LEDs, and add the