Sunday, August 31, 2014

Raspberry Pi PLUS Arduino Esplora = Best of both worlds

First of all, a big thank-you to all who turned out to the Tulsa Mini-Maker Faire on Saturday.  We've conducted the drawing for the door prize and have sent out emails to the winners.  Once we receive responses back, we'll post the names of the winners up here.

For those of you that didn't make it out, I made a display of using the analog I/O capabilities of the Arduino Esplora to drive a packet TNC to put telemetry and message packets out over APRS.  The Arduino and packet TNC were both connected to my laptop computer on the USB ports.  Scott KD5NJR then pulled up my information and displayed it on his laptop that was running APRSIS.

While unloading the Arduino today, decided to take the plunge and interface the Raspberry Pi with the Arduino. The Pi is a great computing environment with all of the capabilities of a fully-featured LINUX box-- not to mention the Python environment for programming.  However, the inputs and outputs are digital.  So, you need to put some type of analog to digital converter between it and traditional analog devices, like resistance thermal devices or temperature sensors.......On the other hand, the Arduino is stricly command line based and not much for graphical user interface or the like.  But is has plenty of input and output lines for analog work!  Even better, the Arduino Esplora has a light sensor, temperature sensor, joystick, push buttons, leds and even a built-in accelerometer.

So, to leverage the best of best worlds, I connected the Raspberry PI to the Esplora board like this:

You will notice that I used the USB hub between the Pi and the Arduino.  The Esplora board is powered off the micro-USB connection, so it's important to have another source of power so that you don't end up rebooting the PI due to excessive current draw.  Plus it allows the keyboard, mouse, and wifi USB connections to be made (since the original Pi only has two USB connections).

Once I pulled up Mincom terminal program and told it to go to the ACM0 serial port (which is the first USB com port) running 9600 bps, my APRS data program started streaming across the Raspberry Pi screen.

So, a Python program using the serial library should be easy to talk and listen to the Arduino.  That will be my next project.....There is some neat stuff we could do have the Pi do the web serving and the Arduino doing the I/O.........

--Jeff AE5ME

Tuesday, August 26, 2014

KD5NJR's Monday Night

I spent Monday evening checking the radio out prior to Maker Faire. Mostly just common sense stuff.

  • Located the radio, power cord and whip antenna among the stuff we took on vacation.
  • Found the radio / computer interface.
  • Started the UZ7HO soundmodem program
  • Verified I had UZ7HO set to listen to the external mic jack on the laptop.
  • Verified I was getting audio from the radio into the computer by looking for "noise" on the UZ7HO waterfall when I cracked the radio's squelch.
  • Verified Windows and UZ7HO agreed with what COM port the radio interface was set to.
  • Set the radio to PKT mode. (Yaesu)
  • Finally I set the radio to 144.390 Mhz. I also set UZ7HO for 1200 baud. In a moment I saw the text of APRS packets.

It didn't take me long to get UZ7HO talking to the APRSIS32 mapping program.
After a while I was satified that APRS was working. So I tuned the radio to 145.01 Mhz.

For "packet radio" I used the EasyTerm program that bundled with Soundmodem ... more on packet later.



Quick facts about "packet radio"

Quick facts about "packet radio".

  • 1. Originally developed in the late 1970s.
  • 2. It's an example of a "store-and-forward" network.
  • 3. The underlying protocol AX.25 is an adaptation of the old X.25 protocol. ( compare it to the Internet's TCP/IP )
  • 4. A TNC connects between your radio and computer. Think of it as a cross between a modem and an Ethernet card.
  • 5. Digipeaters receive weak packet and re-transmit it for others to hear.
  • 6. A 'node' is a more intelligent digipeater.
  • 7. Some TNC firmware contain a small BBS where messages can be left.
  • 8. You can leave a message in a distant friend's BBS by using digipeaters and nodes.
  • 9. There are still full-service BBSes out there with forums, chat and file transfer capability.
  • 10. You can leverage packet radio's infrastructure to communicate with your project at a distance.

Monday, August 25, 2014

M0XER balloon keep on Rollin' !!

APRS website :

Lunchtime look at APRS shows some weather stations , vehicles and "digipeaters". is a pretty slick website.  There is a lot it can do with the information in the APRS-IS servers that monitor the APRS frequency.  

Tulsa Mini-Maker Faire August 30th!


Tulsa's second annual mini-Maker Faire is this Saturday, August 30th from 10 AM to 6 PM at the Tulsa County Fairgrounds.  TDRC will have a display featuring the use of APRS to transmit position and telemetry data.  We should have at least one tracker on site and a computer that will display stations on a Tulsa map.

This will be a good opportunity to meet the TDRC crew and ask questions about our projects.  We will also have two Raspberry Pi computers as door prizes, so be sure to stop by our booth and sign up!

For more information about the mini-Maker Faire, go to this hyperlink: Tulsa_Mini_Maker_Faire.

Quick Facts on APRS

Some quick facts regarding APRS:
  • 1. Automatic Packet Reporting System developed by Bob WB4APR for real-time data.
  • 2. There is a world-wide network of APRS "digipeaters" that boost the signal of APRS transmitters. ( in North America, the network is on 144.390 MHz )
  • 3. Numerous "i-gates" allow APRS messages to cross back and forth from the Internet-based APRS-IS network to the conventional (radio-based) APRS network.
  • 4. Several websites provide a convenient interface to the APRS-IS network.
  • 5. APRS client software exists for a variety of operating systems.
    • (java) YAAC :
    • (windows) APRSIS32 :
    • (linux) XASTIR :
    • Android and iOS apps available too.
  • 6. APRS has been used for
    • SMS-like messaging,

    • vehicle tracking,

    • weather stations,
    • and even telemetry from balloons,
    • rockets
    • aircraft
    • and space craft.

Screen shot : YAAC ( yet another APRS client )

I installed YAAC last night:
Program is written in Java and has a setup wizard.  Doesn't take long to set up and you're monitoring the APRS network via the APRS-IS server system. YACC uses OSM maps by default and you can add TNCs and radios when you're ready to.

Monday, August 18, 2014

Saturday Night Simplex #4

The last stop of the night was historic Reservoir Hill.

Saturday Night Simplex #3

After checking out the Shadow Mountain vicinity, we visited Turkey Mountain's parking lot. Through the trees were nice views of South Tulsa.

Saturday Night SImplex #2

Couple of interesting places to set up and listen for area signals proved to be Steak 'n Shake parking lot near 61st and Elm in BA and the hilltop the old Lutheran Church sits on (see Luther Drive). Both locales provided a nice line of sight right up the BA Expressway. You'll see many tall buildings in downtown Tulsa, for example.
    We worked about 15 stations including:
  • N5TEX Joe in Sand Springs
  • WB5VST Ben in Skiatook
  • The Emergency Operations Center in Tulsa WT5EOC

Saturday Night Simplex #1

Saturday Night the amateur radio emergency management folks got together to practice communication on the "2 meter band" (frequency: about 145 Mhz ). Simplex means that we transmit and receive on the same radio frequency.
Reading between the lines, that means that there is no technology between the two radio users. No repeaters or ways to boost a signal. Just two radio users with a clear line of sight to each other.
So, a couple of us went out to find "high ground" from which we could communicate with many "hams". In the photo, you can see one of many ridges in Tulsa where you can have a good time playing "walkie talkies".