There are plenty of GPS navigation units on the market today, but it’s always fun to build something yourself. That’s what [middelbeek] did with his $25 GPS device. He managed to find a few good deals on electronics components online, including and Arduino Uno, a GPS module, and a TFT display.
In order to get the map images on the device, [middelbeek] has to go through a manual process. First he has to download a GEOTIFF of the area he wants mapped. A GEOTIFF is a metadata standard that allows georeferencing information to be embedded into a TIFF image file. [middelbeek] then has to convert the GEOTIFF into an 8-bit BMP image file. The BMP images get stored on an SD card along with a .dat file that describes the boundaries of each BMP. The .dat file was also manually created.
The Arduino loads this data and displays the correct map onto the 320×240 TFT display. [middelbeek] explains on his github page that he is currently unable to display data from two map files at once, which can lead to problems when the position moves to the edge of the map. We suspect that with some more work and tuning this system could be improved and made easier to use, of course for under $25 you can’t expect too much.
No doubt anyone reading this has access to a few ancient laptops and the displays contained within. While those laptops are probably still stuck with a Gig of RAM and Windows ME, the display panels are probably still good. They don’t have HDMI, DVI, or VGA, though, which means those panels will need a converter.
[Jared] had a different idea. Instead of reusing laptop displays with a converter, why not connect them to an LVDS connector on some modern hardware? He had a RIoT board with a native LVDS connector, and with some clever reverse engineering and PCB fabrication he can put those old displays to work.
[Jared] had a very cool sunlight-readable ‘transflective’ LCD from on old Portege R500 laptop. If he was going to take apart one laptop to use with modern hardware, this was the one. Opening up the display he found a tiny connector but no obvious markings of what pins did what. The datasheet was also not to be found. By shorting two pins together, he could figure out what the pins were: shorting the clock freezes the screen, shorting the HSYNC and VSYNC means the screen loses sync. Blues, reds, and greens can be found the same way.
With the pins identified, a breakout board was in order. This is just a small board to break out the very small wires to solderable pads and a driver for the backlight. With that, and the RIoT with an LVDS output, [Jared] was able to use new hardware with this old but still serviceable display.
[Esai] wanted to build an electronic clock from scratch. A noble quest, but ordinary seven-segment displays are just that – incredibly ordinary. Instead of a few displays that can be bought from the usual retailers for a dollar a piece, [Esai] made his own four digit, seven-segment display on some perfboard.
Before soldering 58 SMD LEDs to a small rectangle of perfboard, [Esai] traced out each segment with a marker. Two LEDs make up each segment, and they’re all connected to a breadboard-friendly pin header with 30 gauge wire.
Each segment is connected as a single column in the LED matrix, and each digit is a row. It’s a simple design, but there aren’t any resistors on this board. Hopefully [Esai] will be using a proper LED driver with this display; you really don’t want LEDs to burn out twice a day at 1:11.
In the high-voltage world, a Jacob’s ladder is truly a sight to behold. They are often associated with mad scientist labs, due to both the awesome visual display and the sound that they make. A Jacob’s ladder is typically very simple. You need a high voltage electricity source and two bare wires. The wires are placed next to each other, almost in parallel. They form a slight “V” shape and are placed vertically. The system acts essentially as a short-circuit. The voltage is high enough to break through the air at the point where the wires are nearest to each other. The air rises as it heats up, moving the current path along with it. The result is the arc slowly raising upwards, extending in length. The sound also lowers in frequency as the arc gets longer, and once [Gristc] tuned his system just right the sound reminds us of the Holy Trilogy.
We’ve seen these made in the past with other types of transformers that typically put out around 15,000 Volts at 30mA. In this case, [Gristc] supersized the design using a much beefier transformer that puts out 11,000 Volts at 300mA. He runs the output from the transformer through eight microwave oven capacitors as a ballast. He says that without this, the system will immediately trip the circuit breakers in his house.
In the demo video below, you can see just how large the arc is. It appears to get about 10 inches long before breaking with a sound different from any Jacob’s ladders we’ve seen in the past as well. Continue reading “11,000 Volt Jacob’s Ladder Sounds Like a Lightsaber”
The Raspberry Pi B+ has a native VGA connection. Sure, it’s hidden away in binary blobs and device trees, and you need to wire up the GPIO pins just right, but it’s possible to connect a VGA monitor to a Raspi B+ natively. For the brave, smart, or foolish, this means you can also drive raw DPI displays. [Robert] had a few of these dirt cheap displays sitting around and decided to give the entire thing a go. It worked, and he’s written down how to do it.
One of the chip architects for the Raspberry Pi, [Gert van Loo], was exceedingly clever when designing the Pi. There’s a parallel interface in the chip that, when combined with a few dozen resistors, can drive a VGA display in addition to the HDMI display. Screens with a Display Parallel Interface are actually pretty similar to what the VGA spec calls for. The problem is, hardly any of this is documented for the Raspberry Pi, and finding it means trawling through forums.
[Robert]’s example circuit uses a 5″ display from Adafruit, a 40-pin breakout, and a bunch of prototyping wires. Setup requires grabbing a cut down version of the device tree used for the Raspi VGA breakout board, setting the output format, rgb order, and aspect ratio of the display, and wiring everything up.
What’s interesting here is that [Robert] reproduced this project from scratch, and found that any display with a 40-pin DPI connector will work with the Raspi, provided you have a datasheet. That’s pretty cool; these displays can be cheap, and since we don’t yet have a proper DSI display for the Pi, this will have to do for now.
Video below of [Robert]’s inspiration for this build, [Ladyada].
Continue reading “Using Cheap Displays With The Raspberry Pi”
A few months ago, the Intel Edison launched with the promise of putting a complete x86 system on a board the size of an SD card. This inevitably led to comparisons of other, ARM-based single board computers and the fact that the Edison doesn’t have a video output, Ethernet, or GPIO pins on a 0.100″ grid. Ethernet and easy breakout is another matter entirely but [Lutz] did manage to give the Edison a proper display, allowing him to run Doom at about the same speed as a 486 did back in the day.
The hardware used for the build is an Edison, an Arduino breakout board, Adafruit display, speaker, and PS4 controller. By far the hardest part of this build was writing a display driver for the Edison. The starting point for this was Adafruit’s guide for the display, but the pin mapping of the Edison proved troublesome. Ideally, the display should be sent 16 bits at a time, but only eight bits are exposed on the breakout board. Not that it mattered; the Edison doesn’t have 16 pins in a single 32-bit memory register anyway. The solution of writing eight bits at a time to the display means Doom runs at about 15 frames per second. Not great, but more than enough to be playable.
For sound, [Lutz] used PWM running at 100kHz. It works, and with a tiny speaker it’s good enough. Control is through Bluetooth with a PS4 controller, and the setup worked as it should. The end result is more of a proof of concept, but it’s fairly easy to see how the Edison can be used as a complete system with video, sound, and wireless networking. It’s not great, but if you want high performance, you probably won’t be picking a board the size of an SD card.
Video demo below.
Continue reading “Running Doom On The Intel Edison”
The seven-segment LED display is ubiquitous. But how old do you think the fundamental idea behind it is? You nixie tube fans will be thinking of the vacuum-tube era, but a reader sent us this patent filed in 1908 where [Frank W. Wood] builds a numeric display with plain-vanilla light bulbs, slots cut in wood, and lots of wires.
The OCR on the patent is poorly done — you’re going to want to download the PDF and read it locally. But as it states in the patent, “Referring again to Fig. 1, the novel arrangement of the lamp compartments will be readily understood.”
Technically it’s not a seven-segment display at all. [F.W. Wood] designed these really nice-looking “4”s with the diagonal heads, and so he needed eight segments per digit. But the basic idea shines through, if you pardon the pun.
The other figures demonstrate the machine that’s used to send the signals to light up the lights. It’s a rotating drum with the right contacts on the bottom side to make connections and turn on the right lights at the other end. Low tech, but it’s what was available at the time.
We’re stoked that we’re not responsible for wiring this thing up, and we’re a bit awed by how old the spirit behind one of our most ubiquitous technologies is.
Thanks to [mario59] for the nostalgic tip!