How small is it? Two things should give you a good sense of scale, the SD card slot on the lower right, and the slide switch on the upper left. This minuscule module is an all-in-one GPS logger which [J3tstream] built.
Main system control is provided by a Teens 2.0 board. If you look really closely you’ll see the SD card slot is actually a breakout board which mounts on top of the Teensy’s pinheaders. Also on the board is a PA6B GPS module with a few passive components to support it. The back side of the board hosts a Lithium Ion battery from an old phone. Note the mangled pin header which works as connectors for the battery. [J3tstream] even built a charger into the project. He’s using an LTC4054 chip to handle the charging. We were a bit confused at first because we didn’t see a way to connect external power. But he goes on to explain that the USB port on the Teensy board is used for charging. Just plug in USB and press the button to get things started.
[Michael] posted up-to-date GPS data sets in the GPX format. These data sets are an alternative to paid updates. Since GPX is a published standard which uses an XML style formatting for location data [Michael’s] time was spent getting the original sets and finding a way to translate them for his Garmin EXTREX GPS.
The original data comes from — hang on, this is a mouthful — the US Federal Aviation Administration’s Facility Aeronautical Data Distribution System (FADDS). He had to apply for permission to download it and to use it in producing a custom GPS build. He grabbed the Airport waypoints and navaid sets, then studied accompanying files detailing the data structure before writing his own Visual Basic 2010 program to spit out the GPX files. He says he wanted to make them available in the spirit of the Open Hardware/Software movement. This may be most interesting for pilots (the kind that put Nooks on the dashboard, not the kind who watch the aircraft from the ground), but we’re sure there’s a myriad of uses for non-pilots alike.
If you’ve ever worried about your car getting stolen this hack can help give you some piece of mind. It’s a cellular enabled geolocation device. These things have been in use for some time, the most common brand we know of is the LoJack. That company gives you a little box to install on the vehicle and if it ever goes missing they can grab the coordinates and forward them to the authorities. This custom version builds a lot into an addon board for an EFM32 board.
The image above shows the main components of the add-on: the GPS module and the GSM modem. Along the top edge of the board is the voltage regulator circuits which aim to keep the standby power to the slightest of trickles so as not to drain the car’s battery. What you can’t see is the SIM card slot which is located on the underside.
You can find the Eagle files for the design at the link above. We’ve embedded the video description of the project after the break.
Continue reading “Roll your own LoJack clone”
The location clock found in the Harry Potter books makes for a really fun hack. Of course there’s no magic involved, just a set of hardware to monitor your phone’s GPS and a clock face to display it.
[Alastair Barber] finished building the clock at the end of last year as a Christmas gift. The display seen above uses an old mantelpiece clock to give it a finished look. He replace the clock face with a print out of the various locations known to the system and added a servo motor to drive the single hand. His hardware choices were based on what he already had on hand and what could be acquired cheaply. The an all-in-one package combines a Raspberry Pi board with a USB broadband modem to ensure that it has a persistent network connection (we’ve seen this done using WiFi in the past). The RPi checks a cellphone’s GPS data, compares it to a list of common places, then pushes commands to the Arduino which controls the clock hand’s servo motor. It’s a roundabout way of doing things but we imagine everything will get reused when the novelty of the gift wears off.
[Andrew Holme] wrote in to tell us about some work he’s done to improve his scratch-built GPS receiver. He figured out a way to use the same hardware but double the number of satellites it can track to a total of eight. When we looked at the original hardware about a year ago it was limited to monitoring just four satellites. That’s the bare minimum for calculating position data. This will not only help increase the accuracy, but remove the problems that would have been cause if just one satellite was dropped because of an obstruction or other issue.
His solution is based entirely on using the FPGA in a different way. He had taken up almost all of the gates available in the Xilinx Spartan 3 chip. Now he’s implemented a CPU on the chip and is able take some of the work off of the hardware gate design by running code on it. He also found and squashed a bug in how the data was processed. He says his original work wasn’t taking into account the rotation of the earth when determining position. All of these improvements put his accuracy at +/- five meters even when he’s not tracking all eight satellites!
[Renaud Schleck] somehow got lucky enough to find a GPS wristwatch in the trash. It had a broken LCD screen so its wouldn’t be of much use on that next hiking trip, but he knew it still had potential. He used the GPS module and a few other parts to build this reverse geocache box.
Reverse geocache is a container that is locked, opening only in a pre-defined geographic location. We’ve seen plenty of these projects around here, like this one that talks, or this one which was given as a Christmas gift. They’re popular projects both because of the unique method of getting at the prize inside, and because it doesn’t take a whole lot of hardware to build one. Once [Renaud] had the GPS module he simply need a user interface, locking mechanism, and a microcontroller to pull it all together.
The interface uses a screen from an old cellphone and one push button. The latching system is a tiny geared motor salvaged from a Laptop optical drive. These, along with the GPS watch board are all monitored by the STM32 microcontroller which he programmed using OpenOCD and the Bus Pirate.
Instead of walking his kid to the bus stop like he used to, [Paul Wallich] lets this quadcopter watch his son so he doesn’t have to. It is quite literally an automated system for tracking children — how wild is that?
The idea came to him when wishing there was a way to stay inside the house during the winter months while still making sure his kid got to the bus stop okay. [Paul] picked up a quadcopter kit and started looking at ways to add monitoring. He found the easiest technique was to include a cellphone and watch via a video chat app. But that is only part of the build as he would still have to fly the thing. After searching around he found a beacon that can be placed in the backpack. It has a GPS module, an RF modem, and runs a stripped down Python scripting shell. Whenever the GPS data changes (signaling his son is on the move) it uplinks with the quadcopter and gives it the new coordinates.
This goes a long way to making your family a police state. May we also recommend forcing the children to punch a time clock?