Camera-based touchscreen input via an FPGA

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[Chonggang Li] wrote in to share a link to the final project he and [Ran Hu] built for their embedded systems class. It’s called Piano Hero and uses an FPGA to implement a camera-based touch screen system.

All of the hardware used in the project is shown above. The monitor acts as the keyboard, using an image produced by the FPGA board to mark the locations of each virtual key. It uses a regular VGA monitor so they needed to find some way to monitor touch inputs. The solution uses a camera mounted above the screen at an obtuse angle. That is to say, the screen is tilted back just a bit which allows the images on it to be seen by the camera. The FPGA board processes the incoming image, registering a key press when your finger passes between the monitor and the camera. This technique limits the input to just a single row of keys.

This should be much simpler than using a CCD scanner sensor, but that one can track two-dimensions of touch input.

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FPGA plays Mario like a champ

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This isn’t an FPGA emulating Mario Bros., it’s an FPGA playing the game by analyzing the video and sending controller commands. It’s a final project for an engineering course. The ECE5760 Advanced FPGA course over at Cornell University that always provides entertainment for us every time the final projects are due.

Developed by team members [Jeremy Blum], [Jason Wright], and [Sima Mitra], the video parsing is a hack. To get things working they converted the NES’s 240p video signal to VGA. This resulted in a rolling frame show in the demo video. It also messes with the aspect ratio and causes a few other headaches but the FPGA still manages to interpret the image correctly.

Look closely at the screen capture above and you’ll see some stuff that shouldn’t be there. The team developed a set of tests used to determine obstacles in Mario’s way. The red lines signify blocks he will have to jump over. This also works for pits that he needs to avoid, with a different set of tests to detect moving enemies. Once it knows what to do the FPGA emulates the controller signals necessary, pushing them to the vintage gaming console to see him safely to the end of the first level.

We think this is more hard-core than some other autonomous Mario playing hacks just because it patches into the original console hardware instead of using an emulator.

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HDMI color processing board used as an FPGA dev board to mine Bitcoins

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The blue board seen above is the guts of a product called the eeColor Color3. It was designed to act as a pass-through between your television and HDMI source device. It boasts the ability to adjust the color saturation to suit any viewing conditions. But [Taylor Killian] could care less about what the thing was made for, he tore it open and used the FPGA inside for his own purposes.

The obvious problem with this compared to a proper dev board is that the pins are not all broken out in a user-friendly way. But he got his hands on it for free after a mail-in-rebate (you might find one online for less than $10 if you’re lucky) and it’s got an Altera Cyclone IV chip with 30k (EP4CE30F23C6N) gates in it so he’s not complaining. The first project he took on with his new toy was to load up an open source Bitcoin mining program. The image above shows it grinding away at 15 megahashes per second while consuming only 2.5 watts. Not bad. Now he just needs to make a modular rack to hold a mining farm.

Playing Meat Boy on an FPGA

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We usually look at these FPGA University projects and think how much fun it must have been to get credit for the work. But in this case we can’t image the grind it must have been to implement the game mechanics of Meat Boy in an FPGA. See how well it came out in the clip after the break.

Remember that with an FPGA you’re basically building hardware devices by using code. The Reddit discussion of the project sheds some light on where to start (and even shares the source code). The Altera DE2 is pushing the game to a monitor using SXGA at 60Hz. The map is laid out as a collection of 32×32 tiles, each represented by 2 bits in memory. [SkipToThe3nd] does go into detail about how the physics work but we can’t even begin to paraphrase that part of the discussion.

The game being cloned here is Meat Boy, the Flash game predecessor to Super Meat Boy. If you’ve never heard of the title we’d suggest watching Indie Game: The Moviea documentary which follows several independent game developers as they try to get their titles to market.

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Building new, weird CPUs in FPGAs

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The popularization of FPGAs for the hobbyist market means a lot more than custom LED controllers and clones of classic computer systems. FPGAs are also a great tool to experiment with computer architecture, creating new, weird, CPUs that don’t abide by the conventions the industry has used for 40 years. [Victor] is designing a new CPU that challenges the conventions of how to access different memory locations, and in the process even came up with a bit of example code that runs on an ARM microcontroller.

Most of the time, the machine code running on your desktop or laptop isn’t that interesting; it’s just long strings of instructions to be processed linearly. The magic of a computer comes through comparisons, an if statement or a jump in code, where the CPU can run one of two pieces of code, depending on a value in a register. There is the problem of reach, though: if a piece of code makes a direct call to another piece of code, the address of the new code must fit within an instruction. On an ARM processor, only 24 bits are available to encode the address, meaning a jump in code can only go 16 MB on either side of its call. Going any further requires more instructions, and the performance hit that comes along with that.

[Victor] decided a solution to this problem would be to create a bit of circuitry that would be a sliding window to store address locations. Instead of storing the literal address for jumps in code, every branch in the code is stored as a location relative to whatever is in the program counter. The result is an easy way to JMP to code very far away in memory, with less of a performance hit.

There’s an implementation for this sliding window token thing [Victor] whipped up for NXP’s ARM Cortex M3 microprocessor, and he’ll be working on an implementation of this concept in a new CPU over on his git.

Pumping 1080p video out of an FPGA

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[Hamster] admits this 1080p HDMI hack for an FPGA doesn’t put a signal that’s fully up to specifications. But as you can see in the image above it does output a 1920×1080 image at 60 Hz, which is the size and frequency of full HD video. It falls just short due to some jitter, which may be just fine if this is only being used for early prototyping and will be replaced with a dedicated encoder later in the design process.

Here he’s chosen a Pipistrello board but thinks that any device which has a Spartan 6 chip with the differential pairs connected to an HDMI socket will work. The difficulty of the task comes in serializing four output channels at 1500 Mb/s each. Because of this just coding your logic isn’t going to work. After roughing out the design [Hamster] went back in and chose to manually place some of the components to ensure that data from each channel arrives at the same time.

While you’re messing with HDMI you may also want to give this overlay hack a try.

A Bitcoin mining example for the BeagleBone with an FPGA shield

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If you’ve got a BeagleBone and an FPGA board you should give this Bitcoin mining rig a try. The hardware uses brute-force to solve hashes, looking for the rare sets that can be used as digital currency. This particular example is designed for the LOGi-bone which is an FPGA shield for the BeagleBone. But we don’t see anything that would make this difficult to use with other FPGA hardware.

We’ve seen FPGA hardware bitcoin mining in the past. It doesn’t offer as much horsepower as an array of GPUs would, but the ARM/FPGA combo can be used in a cluster in order to speed up the process. This sounds like a fun group project to take on at the local Hackerspace.