[Jeri Ellsworth] has been working on a direct conversion receiver using an FPGA as an oscillator and a PC sound card DSP. Being the excellent presenter she is, she first goes through the history and theory of radio reception (fast forward to 1:30), before digging into the meat of the build (parts 2 and 3 are also available).
[Bruce Land] is a professor at Cornell University who was looking for a way to quickly solve chemical kinetic systems. He had used MATLAB but longed for a faster method. His upgrade achieves a 100 times speed increase by using an FPGA as a parallel stochastic solver.
It works by generating 100 pseudo-random 16-bit numbers using an Altera DE2 board. This is done once per cycle at 50 MHz so we’re talking about a lot of random numbers. They are run through the solver algorithms and used to compute each reaction cycle. On a 3.8 GHz P4 process running the MATLAB version one of these cycles would take about 1000 seconds, so the speed improvement can immediately be felt. It’s wonderful to have this new tool. It does make us wonder what could be done with GPU processing that we’ve seen for password cracking or bit coin mining. Much like FPGAs a GPU is prefect for running a large number of parallel operations.
[ Jack Gassett] is working on an FPGA shield for the Arduino. At first the idea of this expansion board seemed a little silly. But [Jack] mentions that the FPGA board can be quite useful for adding higher-order electronic complexity like HDMI capabilities to an Arduino. We’re not totally sold on the idea, but he’s not making the board solely for use with an Arduino either.
The plan is to use a Xilinx Spartan 3A FPGA which comes in a ball-grid array package. And that is the reason [Jack] decided to use Kickstarter for this project. He shared some of his issues with BGA components in a home manufacturing process a while back. To get these working reliably you need to have them professionally assembled, and that requires a sizable upfront investment. But as we read through his proposal it struck us that he’s actually using Kickstarter as a preorder system. You can get a base model with just the FPGA soldered on the board for $55. Not bad considering the chip will cost you at least $20 without assembly. Each level up includes a few more components like SRAM or add-on PCBs.
We get a lot of tips pointing to Kickstarter proposals but this is one of the few that seems right on the mark for supporting open and innovative development. Great work [Jack]!
[Thanks Simon]
[Mike Field] just finished implementing SPDIF generation on an FPGA. SPDIF is an industry standard for transmitting digital audio signals; the acronym stands for Sony/Philips Digital Interconnect Format. It’s been around for more than a decade and since it’s found on most home-audio equipment, building an SPDIF output into your projects may be quite a desirable feature. [Mike] mentions several ideas for this functionality like building high-end test equipment, or providing a high-quality output for electronic instruments.
He first jumped into analyzing the specification in order to determine the hardware requirements. Due to some issues with jitter, he found it necessary to use a 100 MHz clock signal. This pushes the jitter down to +/- 5ns of jitter, which he concedes may raise the hackles of audio purists, but does satisfy the published standard. Output requires just one pin of the FPGA and the five components seen above. A hex inverter (74HC04) voltage divider, capacitor, and RCA connector transmit the 0.5V signal to your audio-receiver of choice. Of course, since TOSLINK fiber optic connectors use the same protocol, you could redesign the output and make this an optical connection.
A week or so ago we featured an FPGA MIDI interface. Since then the builder has gone crazy with his FPGA and revised his code to include polyphony and PWM output, and posted a polyphony demo.
In our previous coverage of the build, the synth was monophonic, and the MIDI implementation was pretty shaky. After realizing the hard work was done, [Mich] re-wrote the MIDI interpretation module to keep 8 voices in memory. Now the synth can play 16th note arpeggios at 999bpm.
The original build used 8 pins to output the audio with an R/2R ladder for a digital to analog converter. This didn’t work well with a polyphonic synth (everything was clipped or noisy), so [Mich] moved to PWM output.
Hacking and digital music seem to be very much related arts. This very well built hack goes through the process of creating a MIDI synthesizer using a field programmable gate array (FPGA) and several other components.
A laptop is used as the MIDI interface which runs through a filter and then to the FPGA. This translated signal then goes through a digital to analog converter and finally to the amplifier and speakers. The FPGA is especially interesting as this chip is an array of logic gates that can be programmed however one wants. In this case, the wavetable principle is used to generate sound.
Although this is no Kaossilator yet, this device is a great start and very functional. If you’ve ever wanted to build your own electronic instrument, check out this hack. Also, check out the video after the break! Continue reading “FPGA MIDI Interface”
Hackaday reader [Louis] wrote in to call our attention to a neat project over at Kickstarter that he thought would interest his fellow readers. The AlienCortex AV is a pre-built FPGA board from [Bryan Pape] with gobs of ports and a ton of potential. At the heart of the board is an Xilinx PQ208 Spartan 3e 500k FPGA, which can be configured to perform any number of functions. The board sports a healthy dose of analog and digital I/O pins as you would expect, along with PS/2 inputs, VGA outputs, and even a pair of Atari-compatible joystick ports.
The AlienCortex software package allows users to easily load projects into the FPGA, which can run up to four different emulated microcontrollers at once. The software comes with half a dozen pre-configured cores out of the box, with others available for download as they are built. The default set of cores includes everything from a 32-channel logic analyzer, to a quad processor Arduino-sketch compatible machine.
Now, before you cry foul at the fact that he’s emulating Arduinos on a powerful and expensive FPGA, there’s nothing stopping you from creating an army of whatever microcontrollers you happen to prefer instead. We’re guessing that if you can run four Arduinos on this board at once, a good number of PICs could be emulated simultaneously alongside whatever other uC you might need in your next robotics project. A single board incorporating several different microcontrollers at once doesn’t sound half bad to us.
