MFJ 1270PI User manual

Brand: MFJ

Model: 1270PI

Type: User manual

Raspberry Pi TNC

MFJ-1270Pi

INSTRUCTION MANUAL

Based on the original by John Hansen

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 INSTALLING RASPBIAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.2 CONFIGURATION PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.3 SERIAL & I

C PARAMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.4 CONFIGURING THE I

C PROTOCOL . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.5 FACTORY RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.6 PORTS & JUMPERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.7 TRANSMIT AUDIO ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3 TECHNICAL ASSISTANCE 11

List of Figures

1 An MFJ-1270Pi stacked on a Raspberry Pi . . . . . . . . . . . . . . . . . . . . . . . 1

2 Opening the terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3 Terminal Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4 Raspi-conﬁg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

5 Interfacing Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

6 Serial Login Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

7 Serial Port Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

8 Script Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

9 pitnc 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.

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!

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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual

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.”

Figure 5: Interfacing Options

When you do this you’ll get the following

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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual

Figure 6: Serial Login Disable

Use the TAB key to highlight NO, then press ENTER. Next you will see

Figure 7: Serial Port Enable

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.

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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual

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 I

C 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.

Figure 8: Script Setup

You will need to download these programs and save them to your Raspberry Pi. Open your

terminal and enter

mkdir /home/pi/pitnc

to create a directory called pitnc.

∗

Next type

∗

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

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

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 b is the bus name or number (/dev/serial0 for the serial port, 1 for the I

C bus), and n is

the device number (0 if using serial, between hexadecimal values 0x3 and 0x77 for I

C). 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

prepend this, the Pi will not ﬁnd the pitnc getparams program. A menu should come up listing

some parameters (Figure 9). If this happens, your Pi and TNC are talking to each other.

If you get a bunch of lines that say

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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual

Figure 9: pitnc getparams Output

retrying...

there is an issue with your TNC or the Pi’s conﬁguration. Check to make sure that the serial port

(or I

C bus) is enabled. If it is, then reset the MFJ-1270Pi as described in Section 2.5 and try

again. If it still does not work, call MFJ Technical Support.

Assuming all is well, you can now set the TXDelay. This is optional, as generally speaking the

default value will work just ﬁne. If you choose to alter it you can do it with the pitnc setparams

program. Here the script format is

./pitnc setparams b n p v

where b and n are the same as pitnc setparams, p is the parameter number from the left-hand

column (i.e. 1 for TXDelay), and v is the value to set. The command to set TXDelay therefore

looks like

./pitnc setparams /dev/serial0 0 1 50.

The transmit delay can be set anywhere from 0 to 255. If you set TXDelay to 0, it will result in

the transmit delay being controlled by potentiometer R6 rather than the value in this menu.

After you have made a change in the pitnc setparams program, you must reboot the TNC in order

for it to go into eﬀect. You do not have to reboot the entire system to do this. Just enter the

following command:

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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual

./pitnc setparams /dev/serial0 0 15 2

2.3 SERIAL & I

C PARAMETERS

• Data Rate: 19,200 baud

• Data Bits: 8

• Parity: No

• Stop Bits: 1

• Handshaking: None

2.4 CONFIGURING THE I

C PROTOCOL

WARNING

This section is for advanced users that need to have multiple devices operating oﬀ of

the GPIO port. It requires editing of system ﬁles via the terminal. If you are unsure

about performing any of these steps, stop and ask for help.

The TNC-Pi can be conﬁgured to communicate with the Raspberry Pi using the I

C protocol.

This is not required for basic operation with a single board on the GPIO port; however, if you ever

desire to run multiple TNC-Pis or anything else that uses the GPIO port, you will need to enable

this functionality. The general procedure for doing this is to start with each TNC set so that it

communicates via the serial port (this is the factory setting) and then conﬁgure each additional

TNC to have a unique I

C address on it. You would need to set these boards one at a time

because only one serial TNC-Pi can be on the TNC-Pi at a time.

To conﬁgure the TNC-Pi for I

C, you will need the two conﬁguration scripts described in

Section 2.2. Before using them, however, it will be necessary to make some additional

conﬁguration changes to the Pi. First, make the following changes to the following ﬁles:

1 In the /etc/modprobe.d/raspi-blacklist.conf ﬁle, comment or remove the line “blacklist

I2C-bcm2708”

2 In the /etc/modules ﬁle, add the line “i2c-dev”

3 Enable the I

C protocol in raspi-conﬁg (Section 2.1)

You may recall that the serial mode format for the pitnc getparams

†

program was

./pitnc getparams /dev/serial0 0

And the format in serial mode for the pitnc setparams program was

./pitnc setparams /dev/serial0 0 p v

Where p is the parameter that you want to change and v is the new value of that parameter. So if

you want to change the I

C address from 0 to 3 you would enter

†

Before running the conﬁguration scripts, ensure that kissattach is not running.

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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual

./pitnc setparams /dev/serial0 0 7 3

After you reboot the TNC, it will now be communicating over the I

C interface. To run

pitnc getparams you would need to enter

./pitnc getparams 1 3

Here 1 is the number of the I

C bus and 3 is the I

C address that you have set. To change a value

when the TNC is communicating with I

C, you simply replace the serial bus and device numbers

with the appropriate I

C values.

2.5 FACTORY RESET

If you ever need to reset these parameters to their original factory values, power down, turn the

TXDelay potentiometer R6 all the way to minimum (counter-clockwise), then power back up. You

should see the yellow DCD LED ﬂash once per second. When you see it ﬂash, you’ll know that the

parameters have all been reset. The power the device back down, move the TXDelay oﬀ of

minimum, and power the device back up.

2.6 PORTS & JUMPERS

The MFJ-1270Pi has several ports and jumpers for various tasks. Their assignments are given

below.

The DE-9 port is intended to be the primary connection to the radio. It should be wired as follows:

Pin 1: TX Audio

Pin 3: Push to Talk (PTT)

Pin 5: Receive Audio

Pin 6: Ground

There are four holes marked “Radio” just behind the DE-9. These can also be used to connect to a

radio. It should be wired as follows (Pin 1 is square):

Pin 1: Receive Audio

Pin 2: Ground

Pin 3: TX Audio

Pin 4: Push to Talk (PTT)

The ICSP pins are for ﬂashing the PIC with new ﬁrmware. The ground pin is highlighted with a

white box. If you are unsure about any step in the update process then call MFJ Technical

Support.

Jumper JP2 allows you to add resistance to the audio output for radios that have more sensitive

inputs than normal. Remove this jumper for Yaesu radios.

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MFJ-1270Pi Raspberry Pi TNC Instruction & Technical Manual

2.7 TRANSMIT AUDIO ADJUSTMENT

Potentiometer R7 adjusts the level of the transmit audio output. Most people will ﬁnd that they

need to set it fairly near the minimum setting. There are two methods to adjust this. The ﬁrst is

to use two radios, one to monitor the transmitted signal and the other connected to the TNC-Pi.

1. Key the radio connected to the TNC-Pi manually by pushing the PTT button on it.

2. On the other radio you will hear a continuous tone even though no data is being transmitted.

3. Turn R7 all the way down, and the tone will go away.

4. Then slowly turn it up until the volume doesn’t increase any further in the monitor receiver.

When you reach this point, back it oﬀ just a little and you should have it about right.

The second method is to have the TNC-Pi to send tones using the following command:

./pitnc setparams /dev/serial0 0 15 3

This will cause the TNC to send 2200 Hz and 1200 Hz tones for about 5 seconds each.

3 TECHNICAL ASSISTANCE

If you have any problem with this unit ﬁrst check the appropriate section of this manual. If the

manual does not reference your problem or reading the manual does not solve your problem, you

may call MFJ Technical Service at (662) 323-0549 or the MFJ Factory at (662) 323-5869. You will

be best helped if you have your unit, manual and all information on your station handy so you can

answer any questions the technicians may ask.

You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial Park Road,

Starkville, MS 39759; by Facsimile (FAX) to (662) 323-6551; or by email to

tec[email protected]. Send a complete description of your problem, an explanation of

exactly how you are using your unit, and a complete description of your station.

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USER NOTES

MFJ 1270PI User manual

Brand: MFJ

Model: 1270PI

Type: User manual

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