Coastal TNC-Pi, TNC-X, TNC-Pi 2 User Manual

TNC-Pi User Guide -1- 6/25/2017

TNC-Pi Assembly Instructions &
Operating Tips

By John Hansen, W2FS

Portions by

John Wiseman, G8BPQ – Linux configuration

Jim Whiteside, M0HPJ – Xastir

Paul Fischer, KC9RGZ – Headless iGate

Document editing support by

Ed Slingland, N2WD

Website

http://tnc-x.com/TNCPi.htm

TNC-Pi User Guide -2- 6/25/2017

Contents

Introduction ................................................................................................... 3

Assembly Instructions ..................................................................................... 4

Parts List ............................................................................................................... 4

Assembly ............................................................................................................... 6

Parts Layout ......................................................................................................... 11

Connecting the Radio .................................................................................... 12

Adjust transmit audio output .................................................................................. 13

Set the transmit delay ........................................................................................... 13

Configuring the Raspberry Pi .......................................................................... 13

Keyboard to Keyboard Connections ......................................................................... 15

Support ....................................................................................................... 16

Application Notes .......................................................................................... 17

Using Xastir ......................................................................................................... 17

Update the package list .................................................................................................. 17

Then install Xastir .......................................................................................................... 17

Kill kissattach ............................................................................................................. 17

Start Xastir ................................................................................................................... 18

Running Xastir ............................................................................................................... 18

More information ........................................................................................................... 18

Configuring TNC-Pi for Use with the I2C Protocol ...................................................... 19

Setup ........................................................................................................................... 19

Get and set parameters .................................................................................................. 19

Running Applications other than LinBPQ with TNC-Pi in I2C mode. .............................. 20

Steps to create an APRS receive-only igate using the Raspberry Pi and TNC-Pi ............. 21

Equipment needed ......................................................................................................... 21

Instructions ................................................................................................................... 22

TNC-Pi User Guide -3- 6/25/2017

Introduction

Thank you for purchasing a TNC-Pi: TNC-X for Raspberry Pi or TNC-Pi 2.

Figure 1: Two TNC-Pi’s stacked on one Raspberry Pi

Figure 2: TNC-Pi mounted on a Raspberry Pi

Figure 3: TNC-Pi 2 mounted on a Raspberry Pi 2.

TNC-Pi User Guide -4- 6/25/2017

Assembly Instructions

Parts List

Your kit should come with the parts listed in the table below. You can use the two
columns of checkboxes to track your progress. As you inventory your parts, put a
checkmark in the first column. Once you’ve installed a part, put a checkmark in the
second column.

Inventoried Installed

Designation

Description

Notes





C1

4.7 uf or 10 µf
electrolytic

Polarized





C2, C4, C5, C6, C11,
C14, C15, C21

0.1 µf monocap





C7, C8

0.01 µf 2.5%

Red and yellow or
grey; if grey marked
10 nF





C9, C10

18 pf ceramic disk





C12, C13

22 pf ceramic disk





C3

100 pf ceramic disk





R1, R2, R3

100K resistor

Brown, black, yellow





R4, R17, R19,

1K resistor

Brown, black, red





R5, R11, R14, R16,
R18

10K resistor

Brown, black, orange





R8

24.9K resistor

Red, yellow, white, red,
brown

TNC-Pi User Guide -5- 6/25/2017





R9

9.31K resistor

White, orange, brown,
brown, brown





R10

18.7K resistor

Brown, grey, purple,
red, brown





R6, R7

10K trimmer
potentiometer

Orange or Blue





X1

3.57 MHz crystal





X2

20.00 MHz crystal





D4

Red LED (PTT)

Polarized





D5

Yellow LED (DCD)

Polarized





Q1

PN2222 transistor

3 pin, flat side (don’t
confuse with U1)





U1

MCP1700-33 or
MCP1700-30 Regulator

3 pin, flat side





U2

CML MX-614 Modem

16 pin IC





U3

PIC16F1847
microcontroller

18 pin IC





U4

MCP6023 Op Amp

8 pin IC





U5

23K640 Memory

8 pin IC





IC Sockets

For U2, U3, U4, U5

One 16-pin, one 18-pin
and two 8-pin sockets





JP3, JP4

2-pin header

Not included in newer
kits

Combined into one 2x2
pin header





2 x 13 extra long
header

2 x 20 in TNC-Pi 2

TNC-Pi User Guide -6- 6/25/2017





9 Pin D-Sub connector





Printed Circuit Board





2 shorting jumpers

Not included in newer
kits

Assembly

Note: John McDonough has published a number of high quality photos of

various stages in the assembly process. See

http://www.qsl.net/wb8rcr/BuildingTheTNC-Pi.html

 Start by installing the parts that lie flat on the board. This includes:

a. all of the 0.1uf monocaps and
b. all of the resistors except for R6 and R7.

R10 and R11 have pads that are rather close together. Be careful
that you do not accidently create a solder bridge between them. Note
that all of the components except for the 26 ( or 40 in TNC-Pi 2) pin
header are installed on the side of the board with the silk screen.

 Next install the two crystals.

Ensure that the 20 MHz crystal is the one nearest the 18 pin IC.

 Next install the IC sockets.

Ensure that the notch on the socket lines up with the notch on the IC outline
on the PC board.

Do not plug the chips into the sockets at this point.

 Next install the rest of the capacitors.

With C1, make sure that the longer lead is placed in the hole marked with a
+.

 Next install the two potentiometers (R6 and R7). You may find these to be a

bit of a tight fit. If so, take a pair of needle nose pliers and flatten the leads
before inserting them into the board.

TNC-Pi User Guide -7- 6/25/2017

 Next install the two LEDs.

Ensure the shorter leads on the LEDs go through the holes closest to the flat
side of the LED outline.

The LEDs can be installed with bent legs so the LEDs point toward the front
of the board. This makes them easier to see when TNC-Pis are stacked one
on top of the other.

 Install the transistor.

Ensure you are installing the transistor rather than the voltage regulator…
they look a lot alike.

 Now install the voltage regulator.

It goes in the three holes above C1. Install it so that the flat side of the
regulator faces away from U3.

 Now install the 9 pin D-Sub connector.

Ensure that you push it all the way in so that it is flush against the board. In

addition to soldering the pins, you’ll gain mechanical stability by soldering

the pins that go into the large round holes on the sides of the connector.

Note: The D-Sub connector is optional. You can install the Radio
header to connect your radio to the TNC-Pi instead. See the section,
Connecting the Radio, for more information.

 Solder in the 2 x13 header. With the TNC-Pi 2 kit this is a 2 x 20 header.

This part is somewhat tricky. It is the only part that is installed through the
bottom of the board.

a. Start by installing this jumper on your Raspberry Pi and then
b. Lower the TNC-Pi board onto the connector so that the body of the

connector is on the BOTTOM of the TNC-Pi board.

c. Now you’ll need to solder the board about a half millimeter from all the

way down in order to prevent the board from bumping into the USB
connector on the Pi. It is not necessary to solder all of the pins. You
should at least solder the 4 pins in the corners (for stability) and the
first five pins on each row (pins 1 – 10).

Your best bet is to carefully trim the solder leads on the part of the TNC-Pi
board that will be on the USB connector side of the Pi to get as much
clearance as possible. You might also want to put a piece of insulating tape

TNC-Pi User Guide -8- 6/25/2017

on top of the USB connector just to be on the safe side. You can then solder
the pins that come through the top of the board.

These pins will allow you to stack a second TNC-Pi on top of the first one if
you choose to do so.

 Now install the 2 x 2 jumper (JP3 and JP4). If your board has a JP7

location, also take a short piece of wire and solder it in here to make a
permanent jumper. Note: If you are building a TNC-Pi 2, none of these

jumpers are needed or included in the kit. If you are building a newer kit
from the original version JP3 and JP4 will also be missing, but you may need
to put a wire across JP7.

 I’ve included 2 4-40 screws and a 5/8” spacer. If you have one of the

Raspberry Pi Rev. B and the original TNC-Pi kit, or if you have the Rev. B+
or Pi 2 and the TNC-Pi 2 kit, you can use this to provide some additional
mechanical stability by putting it between the hole in the Pi and the hole in
the TNC-Pi. If you have a Pi B+ board and the original TNC-Pi kit, these
parts are not needed. There will be plenty of mechanical support from the
extra USB jacks on the Pi board, but you will want to use insulating tape on
these jacks to keep them from shorting the TNC board.

If you are stacking 2 or more TNC’s you might also find it preferable to use a
spacer that is a male to female, rather than female to female. These male to
female spacers are available on the TNC-Pi website.

 Now install jumpers at JP4 and JP3.

They should be installed so they are parallel to the body of the 2x13 pin
connector. If you are building a TNC-Pi 2 or newer original TNC-Pi, none of

these jumpers are needed or included in the kit.

Leave the board connected to the Raspberry Pi and power up the Pi.
Check the voltage between pin 5 (negative) and pin 14 (positive) on
U3. It should read about 3.3 volts. With the notch at the top of the
chip, these pins are the ones half way down the left side (negative)
and right side (positive) of the chip.

If the voltage check is not successful, find and fix the fault before
proceeding.

 Power down the Pi and remove the TNC-Pi board from the Pi,

then install the 4 ICs.

You may wish to bend the pins of the four ICs slightly inward to facilitate
inserting them into their sockets.