MFJ MFJ-1270Pi Manual de usuario
Raspberry Pi TNC
MFJ-1270Pi
INSTRUCTION MANUAL
Based on the original by John Hansen
©2020
MFJ Enterprises, Inc.
300 Industrial Park Rd. Starkville, MS 39759
P: (662) 323-5869
F: (662) 323-6551
DISCLAIMER
The information in this manual is for user purposes only and is not
intended to supersede information contained in customer regulations,
technical manuals or documents, positional handbooks, or other official
publications. The copy of this manual provided to the customer will
not be updated to reflect current data. Customers using this manual
should report errors or omissions, recommendations for improvements,
or other comments to MFJ Enterprises, 300 Industrial Park Road,
Starkville, MS 39759.
Phone: (662) 323-5869
Fax: (662) 323-6551
Business hours: M-F 8:00 AM - 4:30 PM CST.
Contents
1 THE MFJ-1270Pi 1
2 SETUP 1
2.1 INSTALLINGRASPBIAN ................................ 1
2.2 CONFIGURATION PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3 CONFIGURING THE I2CPROTOCOL......................... 9
2.4 FACTORYRESET..................................... 10
2.5 CONNECTINGTHERADIO............................... 10
2.6 TRANSMIT AUDIO ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 TECHNICAL ASSISTANCE 11
List of Figures
1 An MFJ-1270Pi stacked on a Raspberry Pi . . . . . . . . . . . . . . . . . . . . . . . 1
2 Openingtheterminal.................................... 2
3 TerminalWindow...................................... 3
4 Raspi-config......................................... 4
5 InterfacingOptions..................................... 5
6 SerialLoginDisable .................................... 5
7 SerialPortEnable ..................................... 6
8 ScriptSetup......................................... 7
9pitnc getparams Output .................................. 8
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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual
1 THE MFJ-1270Pi
Thank you for purchasing the MFJ-1270Pi Terminal Node Controller ™. This TNC is designed to
perfectly match the popular Raspberry Pi (Figure 1), allowing expasion of existing systems to
support TNC-based operations. The open-source Raspbian operating system provides a powerful
and flexible base upon which to build any packet station. From portable setups to large, fixed
stations, this board has been everywhere. The MFJ-1270Pi Raspberry Pi TNC ™supports the
packet TNC modes used for APRS iGates and Digipeaters and VHF packet for Winlink. It will
support HF Winlink with the addition of a Pactor or similar modem.
Figure 1: An MFJ-1270Pi stacked on a Raspberry Pi
2 SETUP
2.1 INSTALLING RASPBIAN
To use the MFJ-1270Pi, you will first need a working Raspberry Pi. These can be ordered directly
from the Raspberry Pi Foundation at https://www.raspberrypi.org.
To install the Raspian Operating System on your Raspberry Pi, you will need to obtain a micro
SD card and install the OS image on it. The easiest way is to download the Raspberry Pi Imager
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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual
from https://www.raspberrypi.org/downloads. There are versions for Windows, MacOS, and
Ubuntu Linux.
WARNING
Make absolutely sure you are copying the image file onto your SD card, not onto
your hard drive! The Imager will overwrite everything on whatever drive you specify!
MFJ will take no responsibility for loss of data in this event!
After the imager finishes flashing the SD card, insert it into the slot at the base of the Raspberry
Pi. Connect a mouse, keyboard, and monitor to the appropriate ports on the Raspberry Pi then
power up the Pi. At first boot you will login with username “pi” and password “raspberry.” You
may change these later if you wish.
Figure 2: Opening the terminal
The Raspberry Pi’s serial port is disabled by default. To use it you will need to change the Pi’s
configuration. Open a terminal window. You can open it from the desktop as shown in Figure 2,
or you can open it remotely if you have SSH enabled. Type
sudo raspi-config.
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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual
WARNING
With great power comes great responsibility! Your Pi will quite happily erase itself
if you make mistakes with sudo, undoing hours or days of work. If you are unsure of
a command, don’t run it! Always keep a backup just in case!
Figure 3: Terminal Window
Prefacing a command with sudo tells the OS that you want to run the command immediately
following as root. Root is the system administrator account on a Linux machine and has the
priveleges to do whatever it wants. Some advice regarding sudo and root priveleges in case you are
unfamiliar with Linux: do not run commands with elevated priveleges for no reason. As the
warning box above explains, root and other superusers can do anything they want to the operating
system, up to and including breaking it! Always take a moment to think through commands before
running them, especially as root! Do you really need to run them as root? Can they be effective
with normal user priviledges? Pausing and thinking through things like this can prevent the
frustration of watching everything you spent the past few days building disappear behind a
blinking cursor forever (or at least until you work up the willpower to start again). Some functions
such as raspi-config must be run as root simply due to their nature (they by design make
system-level changes), but never develop the habit of just running commands as root for no reason.
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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual
Once you input the command, the following box will appear.
Figure 4: Raspi-config
Use the cursor keys to scroll down to “#5, Interfacing Options.” Then, on the next screen scroll
down and select “P6 Serial.”
When you do this you’ll get the following
Use the TAB key to highlight NO, then press ENTER. Next you will see
Use TAB to hightlight YES this time and press ENTER. Next, use TAB to highlight FINISH then
press ENTER. The Raspberry Pi will ask to reboot. Tell it yes.
It is a good idea to make sure Raspbian is up to date. If the Pi has internet access, you can do this
from the command line by entering the following:
sudo apt update && sudo apt upgrade
2.2 CONFIGURATION PROGRAMS
The programs pitnc getparams and pitnc setparams are used to display and change parameters
stored in the TNC-Pi board, including the TXDelay and the I2C address. The pitnc getparams
program will also provide you with a convenient way to make sure that your TNC is successfully
talking to the Raspberry Pi.
You will need to download these programs and save them to your Raspberry Pi. Open your
terminal and enter
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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual
Figure 5: Interfacing Options
Figure 6: Serial Login Disable
mkdir /home/pi/pitnc
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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual
Figure 7: Serial Port Enable
to create a directory called pitnc.∗Next type
cd /home/pi/pitnc
to move into the new directory. There are two ways to download the zip file containing the two
programs. The first is to type
wget https://cdn.shopify.com/s/files/1/0289/7782/3843/files/params.zip
into the terminal. The second is to navigate the Pi’s web browser to www.mfjenterprises.com
and download the software from the MFJ-1270Pi product page. Once the file is downloaded and
placed in the /home/pi/pitnc directory, the command
unzip params.zip
will unpack the zip archive into two files. If you now enter ls -l, you will see the original zip file
and the two scripts. Note that both are colored white and are preceded by the characters
“-rw-r--r--”. This is Linux shorthand for who has what permissions. The first dash indicates what
type of object is present. In this case, it is a file, so the space is a hyphen. The next three
characters are the user’s permissions. In this case the user can read (r) and write (w), but not
execute (x), these files. The next three are for the user’s group (they can only read), and the final
three are for all users (again, they can only read). We need to give ourselves execute permissions
for these two scripts, and the command to do that is
∗If you have created a different user, replace “pi” with your new username
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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual
Figure 8: Script Setup
chmod u+x pitnc*.
This instructs the OS to change mode (chmod) by adding execute permissions for the user (u+x)
to all files beginning with pitnc (pitnc*). Typing ls -l again now shows the two scripts in green
with an “x” now included in the permission string. We can now use these scripts to configure the
TNC-Pi. Your terminal should now look like the one in Figure 8.
If you are not already there, switch to the directory that you placed these programs in by using the
cd command just like earlier. The format for this script is
./pitnc getparams b n
where bis the bus name or number (/dev/serial0 for the serial port, 1 for the I2C bus), and nis
the device number (0 if using serial, between hexadecimal values 0x3 and 0x77 for I2C). Run the
following command:
./pitnc getparams /dev/serial0 0.
The ./ at the beginning of the line tells the Pi to look in the current directory. If you don’t
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