TNC-X - The Expandable TNC
Just $48!
X-Digi is Now Available!
uSmartDigi is Now Available!
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TNC-X Documentation Page (manual, schematic, source code, etc.)
Setting Up TNC-X to work with AGWPE, AGWTerm, and WinLink 2000
NEW! NEW! NEW! =>
uSmartDigi is Now Available!
An Extremely Configurable Digi DaughterBoard for TNC-X!
X-Digi is Now Available!
An Inexpensive Digipeater Daughterboard for TNC-X!
X-Track is Now Available
An Inexpensive Tracker Daughterboard for TNC-X!
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TNC-X board without the USB or case options. (Circuit board is 3.8 x 2.5 inches) |
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TNC-X with USB option installed |
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TNC-X is a new Terminal Node Controller (kit) design based on the Chepponis/Karn KISS protocol. It is implemented using a Microchip PIC 16F628A microcontroller, a CML MX614 Bell 202 modem chip, an 8K Ramtron FRAM, a Maxim MAX232A level converter chip, and an op-amp which provides active audio filtering for the modem. From the beginning, this TNC was designed to be small, have low power consumption, and, most importantly, be expandable. Expandability stems from two sources. First there is an on board socket for a USB module which provides the TNC with a USB port. Drivers that are shipped with the module make it appear to the host PC as a standard serial port. Thus PC software that expects to see a serial port on the computer will interpret the TNC-X as being connected to such a port, even when the PC has no serial ports, or they are all used by other applications. In addition, when the USB option is used, the TNC can be powered from the USB port of the computer; no other power supply is needed.
TNC-X is also expandable via an expansion header that allows the addition of "daughter boards". Power is provided to the daughter board through the expansion header. In addition, signals that would otherwise go to or from a host PC can be intercepted by the daughter board at the TTL level and processed. The I/O on the expansion header speaks "KISS" so that any daughter board only has to send and receive data packaged in KISS format to access the core module. This makes the development of daughter boards fairly simple and inexpensive. For example, daughterboards are now available that can turn TNC-X into either of two types of digitpeters (see uSmartDigi and X-Digi) or into a stand alone Tracker (see X-Track).
In addition, the expansion header provides access to a second on board serial port. The X-Track daughterboard, for example, uses this port to receive data from a GPS receiver. The data is then processed and formed into packets and an APRS beacon is sent.
Even without daughter
boards (or the USB module) the device works as a fully functional stand
alone KISS mode TNC. The idea behind the expansion options was to provide
a platform that would allow additional functionality to be added to the
unit with the investment of very little design time and very few parts.
A complete technical description of TNC-X is provided in a paper that was presented at the 2003 ARRL/TAPR Digital Communications Conference in late September in Hartford Connecticut. A copy of this paper can be accessed here. Please note that there have been a few design changes since the publication of this paper. At some point I will revise the paper, but I've not as yet had an opportunity to do so.
Any questions concerning TNC-X can be directed to the developer, John Hansen, W2FS.