TNC-96K Resources

This is where you will find current resources for the TNC-96K

Project Ideas - A list of possible projects associated with the TNC-96K


Drivers for TNC

Teensy Loader - Used to upload TNC-96K Firmware

Standalone TNC-96K Teensy 3.2 Firmware

Raspberry Pi TNC-96K Teensy 3.2 Firmware

TNC-96K Source Code

TNC-96K Utility Software

Add Bluetooth to your TNC

Current Board Design

TNC Case

A little information about the TNC-96K project.

I first came across the TNC-Pi9k project around December of 2017.  I believe it was after watching a video of Mark Griffith where he introduced the TNC-Pi9k (  I sent an email to John Wiseman the developer of the TNC-Pi9k asking for more information and he was very gracious in providing the necessary files and encouraged modification to his existing designs.  You can follow the conversation here.

After successfully building a batch of TNC's I send the following email to John asking if it was ok to make changes and to put kits together for others.  His response is below.
John Wiseman <>
Dec 24, 2017, 2:46 PM
to me
Yes, feel free to make any improvements you think make sense.
The problem with the micro usb is that it is part of the Teensy, so
Isn't easy to replace. A jumper cable to another socket makes sense. The
board was originally designed to use with a Raspberry PI, but a lot of
people are using it stand-alone via USB. The wifi option using the ESP
only really makes sense if you have the radio away from the PC location,
or want to operate using a tablet.
I've no problems with you putting kits together.
On 22/12/2017 17:38, Mat Murdock wrote:
> I just wanted to drop you a note and let you know that I have really
> enjoyed working on the Pi9k board.  I appreciate your willingness to
> answer questions.  I am fine tuning the 9600 baud settings as well as
> getting the proper capacitors for c5 and c8.
> There are a few tweaks I think I will make to the board for the next
> run, ie getting all the labels the same size, changing the polarity on
> that lone led.  I also want to see if I can add a jumpers to bypass c5
> ad c8 so that the caps can be installed, but easily bypassed if not
> needed.  I am also looking at the possibility of converting the micro
> usb to a usb type B. Micro usb is so fragile so maybe a little cable
> or a little board the has micro male on one side and type b female on
> the other side that sits perpendicular to the main board and held in
> place by a case... Who knows, just thinking out load.  I like having
> it powered off of usb so using that same port as data is preferred vs
> going through esp ports.
> Do you mind if I put together kits for people?  There seems to be some
> interest.  I plan on getting some together for our local club and
> figured while at it I can make them available to the others as well.
> I just didn't want to step on anyone's toes.
> Let me know your thoughts.
> Happy Holidays!
> Mat
Following his response I started making modifications to board and the current version is the result of that. I continue to help fellow operators get their TNC's working and online both locally and remotely when possible.

All of the profits from the boards sold go to the WVCARC.  I do not make any money off of them, and if I was to take into account the time spent on producing the boards, the cost of stocking the kits, the time spent going to the various Amateur radio events.  I have lost more money then then the club has taken in.

My source code and board design are all available online for anyone to download and create their own boards.  I figure the more TNC's out there the better.  Regarding the anonymous poster below, I could of just deleted your post, but I felt that the premise of your question should be addressed.  I did not copy Coastal Chipworks.  They received the same permission and design files I did from John.  I started producing kits many months before they did.

My board retains all of the debugging and test points so that users can hack away at the board.  The Coastal Chipworks version has removed many of them while retaining the same functionality.  I generally ship with a Teensy 3.2 as it is less expensive and is all that is required for general packet use.  It still supports the Teensy 3.6.  The Coastal Chipworks version ships with a Teensy 3.6.

Both boards have there place in the community and I am excited to see a renewed interest in Packet.


  1. I bought the TNC ket at RMDC2019. I've assembled it, I think. Two capacitors (C5,C8, 1mF each) are electrolytic and not bi-polar (ceramic) so I haven't installed them as I've no idea what polarity to use, if any.

    Big deal is that now that it is built, what happens next? There are drivers listed. What are they for? What role does/can a Raspberry Pi play? How do I upload the source files.

    Next question is how it is actually deployed. I'm assuming that the DB9 connects to my computer (which doesn't have a serial port so I need to buy some kind of a USB to Serial device, I guess) and that the DIN connects from the TNC to the radio??

    What software do I run on the PC ... can it be a Raspberry Pi? Windows 7?

    Roland Smith, K7OJL

  2. Would it be possible to create a Teensy 4.0 firmware?
    These are as cheap as any version I can buy here in Oz (my skills are low to non existent).

    Tim VK3ONE

  3. The Teensy 4.0 does not have a DAC which is required. John Wiseman was looking into what would be required to make it work.

  4. I was hoping to take a peek at the source, but the link isn't working. Any chance you could post/send and updated link?

  5. I bought the pre-assembled and tested board (for RPi4). I'm an arduino newbie. JP3 and JP4 are in different positions than shown in your manual. Is that intentional? Also when I try to flash the teensy with either the 3.2 or 3.6 image, Teensy Loader 1.52 reports:

    3:44:55.971 (loader): File "Pi9k Raspberry Pi Firmware Teensy36 04162020 (1).hex". 75408 bytes, 117% used
    13:44:55.971 (loader): File contains data beyond chip size, yikes!

    I'm probably doing 10 things wrong. But I'm at a loss as to how to proceed.

    1. I sent you an email regarding the jumpers on Feb 6, 2021. You do not need to reflash the TNC as it is ready to go. If you feel the need to do it you will want to use Pi9k Raspberry Pi Firmware Teensy36 04162020.hex


  6. Matt, Have you had anyone report the board getting stuck in a transmit loop. I am using one of your boards on a BPQ Node/RMS Gateway and every once in a while It will get stuck when beaconing. It loops my beacon over and over without space. The only thing I can do is kill power to the node to reset the TNC. If I kill the BPQ daemon I can't access the TNC via serial or the tools. It has happened about 5 times now. It is a totally random amount of time between. I love the TNC and the configuration. Just kind of stumped. I am almost thinking that it is some odd chr coming from BBS traffic.
    Thanks Much WA9JG

    1. I would post your issue here and see if anyone has suggestions for you.