Tag: sensors

GPS on Raspberry Pi

Successfully installed this GPS board on the R-Pi.

By Kevin Townsend at adafruit.com


The drivers for the console cable were already in the Raspian distribution on the R-Pi.

I installed the gpsd (daemon) software as directed in the above tutorial.

Documentation for gpsd is here:


Sample C code is: gpxlogger.c and cgps.c – which can be found in tkzic/rpi/gpsd 3.7/

(todo – write sample code and add to telemetry tracker)

HAB APRS tracking

Notes on high altitude balloon tracking using APRS.

Byonics TT3 is another option – a separate APRS encoder, to be combined with GPS and transmitter, for example:

What are all the pieces I will need to make a complete TinyTrak APRS tracker?

  • You will need:
    • a TinyTrak3 or TinyTrak4 controller (The primary difference is that the TinyTrak4 can decode incoming stations, so you can monitor others if you connect a computer.)
    • a serial GPS recevier, such as our GPS2. (We sell both TinyTraks as a combo above with a GPS2.)
    • a radio/power interface cable to connect to the mic & speaker or data jacks of the 2 meter mobile or handheld radio you will use. (If you don’t have a radio, consider our Micro-Trak line which include the transmitter.)
    • a F-F null modem cable to connect the TinyTrak to your computer serial port for configuration, and possibily for operations for the TinyTrak4.
    • a USB to serial adapter if your computer doesn’t have a serial port.

Arduino INPUT_PULLUP mode


When reading the value of a switch with Arduino, its useful to set the INPUT_PULLUP mode so you don’t need to use an external pullup resistor. By the way, the internal pull-up resistor is 20K ohms.

See this tutorial:


If its not clear what a pull-up resistor does,  read the links on this forum post.


Everybody has their own way to explain it. I would say that when the switch is open, the pull-up resistor weakly pulls the logic value high, so you don’t get random signal readings.


Arduino pachube (cosm) feed for musical stairs

(update) the feed is working – I changed the datastream name from sensor_value to count – and just had it upload a random value every time for testing.

Some initial testing with the Ethernet shield encountered missing libraries when compiling the example sketch which cosm.com provides when setting up an Arduino type feed.

Here is the forum post which explains which libraries are missing:  http://community.cosm.com/node/1694

and here is the helpful quote…

You should try using new official Cosm library for Arduino.

You can download a snapshot zip file here:

You will also need this HTTP library:

See here for more details on how to install a 3rd-party
library on different OS:

You will find a bunch of usefull examples within the
Cosm library. Please let me know if you have any questions.