Friday, December 12, 2014

APRS Arduino with map display

APRS Map on 2.2" TFT

While reading the chapter on Marinus: An APRS Display from the Ham Radio for Arduino & Picaxe by Leigh L. Klotz, Jr, WA5ZNU. I decide to give it a try over the weekend.

Ham Radio for Arduino & PICAXE

Initially it sounded complicated but after looking into my inventory ( Arduino, TFT display, SD card and APRS modem ), I have ALL the similar items needed to do this project.

I replaced the Arduino UNO with a DigiX , an enhanced Arduino DUE with Wifi, SD card, nRF and many more pins. The reason for this was for both mcu power, flash & memory storage and operating voltage of 3.3V as most of the TFT out there runs on 3.3V.

The next, I replaced the Adafruit display shield with a bigger and commonly used  2.2" TFT / ILI9341 (320x240) that runs on SPI. The Arduino forum here have lots of info on this display. This display runs on 3.3V only. As I have gotten this 2.2" TFT working on Adafruit GFX library before, it is just a matter of hooking up the pins correctly.

The SD card slot was built-in to the DigiX on pin 87 as Chip Select (CS). Nice...

MicroAPRS modem

The last piece, instead of Argent Radio Shield, I'm using an Open Source version of Arduino MicroAPRS modem by markqvist from The above is a picture of the MicroAPRS modem board I made on DIY PCB.

For the library, DB1NTO modified the ArgentRadioShield library for the MicroAPRS for decoding the normal and compressed packets functions.

All the main codes remains the same as I just modified the TFT & ArgentRadioShield library only.

The image below are the whole system, DigiX with SD card, 2.2" TFT display, 5V to 3.3V from the MicroAPRS modem to the Serial3 of DigiX.

Marinus on DigiX / MicroAPRS
With help from the author WA5ZNU, I was able to generate the OSM map tile for 320x240 to match my 2.2" TFT display. Since I'm using a "bigger" Arduino with lots of memory, I generated a 7x7 tile to be stored inside the SD card.

OSM 7x7 map tiles

With everything setup, I put everything inside a plastic box and go for a ride. Below are some of the pictures and decoded callsigns on the maps.

APRS Map decoding my 9W2SVT-8 packets

APRS Map inside a plastic box



Summary hardware :-

Special thanks Leigh L. Klotz, Jr, WA5ZNU for the great article and his assistance to get everything up and running. Markqvist for the MicroAPRS modem and Taner DB1NTO for the modified MicroAPRS library to support for packet decoding for normal and compressed packets.

Summary Links :-

Wednesday, December 10, 2014

Updated SVTrackR with mini 0.96 OLED display

After a few months of testing and development, I have reach a milestone of version 1.0 with all the necessary functions and features.

SVTrackR with OLED
The functions and features of this APRS Tracker called SVTrackR are :-

  • Super bright 0.96" mini OLED display
  • Decodes mic-e / compressed packets
  • Calculate distance to station from received packets
  • Calculate bearing to station from received packets
  • Display two decoded packets in multiple lines
  • Decodes and display messages for the callsign
  • Top section display GPS lat/lon and number of satellites
  •  Lower section display important counters, speeds, heading and altitude
  • Enhance Smart Beacons 
  • Calculate distance to base station location
  • Display uptime / minutes since power-up
  • Sequence number of every packet to detect packet loss
  • Byte saving by sending status every 10 packets
SVTrackR message

The OLED screen are bright enough during the day and are made for you to glance it during stops. It was NOT design to view it during driving as the text are too small.

The mic-e / compressed packet was decoded as 9M2NIA-9 was 142 degree, 6km away from my current location.
SVTrackR mic-e decoded