GPS For A Graphing Calculator

GPS [Chris], graphing calculator hacker extrordinaire, has seen a few of his projects show up on the front page of Hackaday, mostly involving builds that turn graphing calculators like the TI-84 Plus shown above into something that copies a few features from a smartphone. His latest build, a hardware GPS module attached to the TI-84 Plus, is yet another feather in his cap of awesome and impractical addition to a classic piece of hardware.

There were two major technical challenges behind adding GPS to a graphing calculator. The first of these was powering a GPS sensor. Many a calculator modder has put a lot of work into documenting the USB port on the 84 Plus, revealing it is a USB OTG port, capable of serving as a host or device. It also supplies 5V of power to just about anything, burning through batteries as a result.

The next challenge was reading the data coming off the GPS sensor at 4800bps.The TI-84 Plus series of calculators have a series of interrupts that can fire at fractions of the 15MHz clock. By setting the timer up to fire every 197 clock ticks and dividing again by 16, [Chris] can read data at 4758.9bps. It’s close enough to get most of the data, and the checksum included in the NMEA protocol allows the software to discard bad messages.

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GPS Engagement Ring Box

gpsEngagementRingBox

[James] got engaged recently, in part thanks to his clever GPS Engagement Ring Box, and he sent us a brief overview of how he brought this project to life. The exterior of the box is rather simple: one button and an LCD. Upon pressing the button, the LCD would indicate how far it needed to be taken to reach a pre-selected destination. After carrying it to the correct location, the box would open, revealing the ring (and a bit of electronics).

Inside is a GPS antenna and a Stellaris Launchpad, which are powered by three Energizer lithium batteries to ensure the box didn’t run out of juice during the walk. To keep the lid closed, [James] 3D printed a small latch and glued it to the top of the box, which is held in place by a micro servo. Once the box reaches its destination, the microcontroller tells the servo to swing out of the way, and the box can then open. As a failsafe, [James] added a reed switch to trigger an interrupt to open the box regardless of location. It seems this was a wise choice, because the GPS was a bit off and the box didn’t think it was in the correct place.

Swing by his blog for more information on the box’s construction and the wiring. We wish [James] the best and look forward seeing his future hacks; perhaps he’ll come up with some clever ones for the wedding like our friend Bill Porter.

$20 GPS/GLONASS/Beidou Receiver

navspark

Sticking a GPS module in a project has been a common occurrence for a while now, whether it be for a reverse geocache or for a drone telemetry system. These GPS modules are expensive, though, and they only listen in on GPS satellites – not the Russian GLONASS satellites or the Chinese Beidou satellites. NavSpark has the capability to listen to all these positioning systems, all while being an Arduino-compatible board that costs about $20.

Inside the NavSpark is a 32-bit microcontroller core (no, not ARM. LEON) with 1 MB of Flash 212kB of RAM, and a whole lot of horsepower. Tacked onto this core is a GPS unit that’s capable of listening in on GPS, GPS and GLONASS, or GPS and Beidou signals.

On paper, it’s an extremely impressive board for any application that needs any sort of global positioning and a powerful microcontroller. There’s also the option of using two of these boards and active antennas to capture carrier phase information, bringing the accuracy of this setup down to a few centimeters. Very cool, indeed.

Thanks [Steve] for sending this in.

Build a Cheap Airplane ADS-B Radio Receiving Tracking Station

airplane tracking with ADS-B radio receiving

Do you have commercial or general aviation flying over your home or near your home? Would you like to know more about these airplanes: identity, heading, speed, altitude and maybe GPS data along with even more information? Well then [Rich Osgood] has just the project for you and it’s not that expensive to set up. [Rick] demonstrates using a cheap USB dongle European TV tuner style SDR (software defined radio) tuner that you can get for under $30 to listen in on the Automatic Dependent Surveillance-Broadcast (ADS-B) 1090 MHz mode “S” or 978 MHz mode “UAT” signals being regularly transmitted from these aircraft.

He steps us through configuring the radio to use a better antenna for improved reception then walks through detailed software installation and set up to control the radio receiver as well as pushing the final decoded data to mapping software. This looks like a fascinating and fun project if you live near commercial airways. You won’t need a license for this hack because you’re only listening and not transmitting, plus these are open channels which are legal to receive.

There are some frequencies you are not legally allowed to eavesdrop on—private communications for residential wireless telephones and cellular frequencies to name just a few (Code of Federal Regulations Title 47, Part 15.9). So remember you do have to be careful and stay within legal frequencies even if your equipment is not restricted from such reception. Also note that just because you have a legal right to intercept conversations or data on some frequencies it could be illegal to publicly share the intercepted content or any details on the reception or decoding (just saying for the record).

We wonder if [Rick] could partner with [G. Eric Rogers] to upgrade [Eric’s] motorized telescope airplane tracking system to extrapolate the radio telemeter data into vector data so his Arduino can track without relying on a video feed. That merger might just get them both on a short TSA list.

Join us after the break for some extra informational links and to watch the video on setup, installation and usage of this cheap airplane tracking rig.

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A Low-Cost Modular High Altitude Balloon Tracker with Mesh Networked Sensors

[Ethan] just tipped us about a project he and a few colleagues worked on last year for their senior design project. It’s a low-cost open hardware/software high altitude balloon tracker with sensors that form a mesh network with a master node. The latter (shown above) includes an ATmega644, an onboard GPS module (NEO-6M), a micro SD card slot, a 300mW APRS (144.39MHz) transmitter and finally headers to plug an XBee radio. This platform is therefore in charge of getting wireless data from the slave platforms, storing it in the uSD card while transmitting the balloon position via APRS along with other data. It’s interesting to note that to keep the design low-cost, they chose a relatively cheap analog radio module ($~40) and hacked together AFSK modulation of their output signal with hardware PWM outputs and a sine-wave lookup table.

The slave nodes are composed of ‘slave motherboards’ on which can be plugged several daughter-boards: geiger counters, atmospheric sensors, camera control/accelerometer boards. If you want to build your own system, be sure to check out this page which includes all the necessary instructions and resources.

Long-distance High Frequency APRS Tracking Using The FreeTrak63

FT63_857_etrex

If you dabble in the ham radio hobby we’re sure you’ve heard of GPS position monitoring or tracking using APRS packet data commonly transmitting over the VHF ham band and FM modulated. One of the issues you’ll face using this common method is range limitations of VHF. [Mike Berg] a.k.a [N0QBH ] tipped us off to his latest project to greatly increase the range of a standalone APRS system utilizing the HF bands on single-sideband (SSB).

There are some unique challenges transmitting packet data using SSB over HF bands.  High Frequency APRS has been around for decades utilizing FSK AX.25 packet transmissions at 300 baud, but it was quite susceptible to noise and propagation aberrations. More recently PSK-31 at the slower 31 baud speed helped alleviate many of these issues. [Mike] utilized the somewhat updated APRS with PSK-63 and the “APRS Messenger” program to overcome these challenges. [Mike’s] hardware solution consists of a PIC 16F690 micro which is coded to receive data from a GPS receiver, convert it into PSK-63 and then transmit on 30 meters over an attached HF radio. A second receiving station or stations at great distances can pick up and decode the transmission using the “APRS Messenger” program connected to the receiving radio over the computer’s soundcard. The program can then forward the tracking information, if good, to tracking websites like FindU.com and APRS.FI.

You can build your own FreeTrak63 by downloading [Mike’s] parts list, assembly code, HEX file, manual and schematic. The PCB is available on OSH Park if you don’t want to make your own or wire point-to-point. Let’s not forget to mention how hackable this hardware is, being really just an eight bit DAC, micro, serial in and radio out. One could reprogram this hardware to do other modulation schemes like AX.25 packet or MFSK16, the sky’s the limit. If short-distance on VHF with existing Internet linked receiver networks using an Arduino compatible platform is more to your taste, then checkout the Trackuino open source APRS Tracker.

Sailing With An Autopilot

sailboat

After seeing an autopilot for a kayak a few days ago, [Mike] thought he should send in his version of a water-borne autopilot. Compared to something that fits in a one-man kayak, [Mike]‘s creation is a monstrous device, able to keep a largeish sailboat on a constant heading.

To keep track of the ship’s bearing, [Mike] is using a very cool digital compass that uses LEDs to keep a steady heading. Also included is an amazingly professional and very expensive 6 axis IMU. To actually steer the ship, [Mike] is using a linear actuator attached to the tiller powered by a huge 60 Amp motor controller. The actuator only draws about 750 mA, but if [Mike] ever needs an autopilot for a container ship or super tanker, the power is right there.

For control, [Mike] ended up using an Arduino, 16-button keypad, and an LCD display. With this, he can put his autopilot into idle, calibration, and run modes, as well as changing the ship’s heading by 1, 10, and 100 degrees port or starboard.

From a day of sailing, [Mike] can safely say his autopilot works very well. It’s able to keep a constant heading going downwind, and even has enough smarts to tack upwind.

Videos below.

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