APRS Tracker

13 March 2017

Here is a very simple Arduino based APRS Tracker created with an Arduino Nano, an HC-05 Bluetooth Module, 8 resistors, 2 capacitors and a general purpose NPN transistor. Used in conjunction with a Smartphone running APRSdroid, it makes for a compact tracking package. The Arduino Tracker is based on an earlier Mobilinkd Tracker design you can find at http://www.mobilinkd.com/2014/09/11/arduino-kiss-tnc/. I added the HC-05 Bluetooth Module so a Smartphone can control the tracker without a cable attached to the phone. The only cable is between the tracker and the radio.

Here's the schematic:

R1-100k, R2-10k,R3-1k, R4-2.2K, R5 and R6-10K, R7-1k, R8-2.2K
C1-100nf, C2-10nf
Q1-NPN Transistor such as 2N2222, 2N3904 etc.

and a photo:


As a power supply, I'm using a battery pack composed of 6 ea. AA NImH batteries, but a single 9v battery will also work.

To flash the firmware into the Nano, you will first need to download the compiled HEX file from Github. 

The file is at https://raw.githubusercontent.com/mobilinkd/tnc1/arduino/images/mobilinkd-473-arduino.hex

For instructions on flashing the firmware, check out http://www.wt4y.com/arduino-bootloader. This is by no means the only method and you may have your own favorite programmer so have at it.

Your Nano should now be an APRS KISS TNC.

The Nano TNC communicates with the Bluetooth at a baud rate of 38400,8,N,1 but the default communications baud rate of the HC-05 module is 9600. To change this and optionally change the Bluetooth's Name and Password, see http://www.martyncurrey.com/arduino-with-hc-05-bluetooth-module-at-mode/ for a tutorial on changing these parameters. The AT command to change the baud rate is AT+UART=3800,1,0
Note: AT+UART=<Param>,<Param2>, <Param3> (Param1: Baud, Param2: Stop bit, Param3: Parity) see https://www.itead.cc/wiki/Serial_Port_Bluetooth_Module_(Master/Slave)_:_HC-05

The last component is a Smartphone running APRSdroid. The are many tutorials on the web for configuring APRSdroid to interface via Bluetooth a KISS TNC.