Want To Play Pong On Your Oscilloscope?

August 1, 2011 by Kevin Dady 15 Comments

I always have! I don’t know why, but I like the idea of using an oscilloscope screen as a general use video display. Why not? In my case it sits on my desk full time, has a large screen area, can do multiple modes of display, and is very easy control.
Making an oscilloscope screen do your bidding is an old trick. There are numerous examples out there. Its not a finished project yet, so be nice. It is actually rather crude, using a couple parts I had on hand just on a whim. The code is a nice mixture of ArduincoreGCCish (I am sorry, still learning), and includes the following demos:

Simple low resolution dot drawing
A font example
A very quickly and badly written demo of pong

The software runs on an Attiny84 micro controller clocked at 16Mhz, paired up with a Microchip MCP42100 dual 100k 8 bit digital potentiometer though the Attiny’s USI (Universal Serial Interface) pins. This is a fast, stable and accurate arrangement, but it requires sending 16 bits every time you want to change the value of one of the potentiometers so its also very piggy. I was just out to have some fun and did not have a proper 8 bit DAC. This was the closest thing outside of building one.
Join us after the break for pictures a (very) brief video and more.

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Displaying Graphics On An Oscilloscope

June 10, 2011 by Brian Benchoff 6 Comments

[Andrew Rossignol] was curious one day and decided that he wanted to display graphics on an oscilloscope after playing around with the X and Y inputs.

[Andrew] started out with a resistor ladder on the DAC of his AVR Butterfly. He was able to to draw a line on the oscilloscope’s screen but bandwidth limitations forced him to reconsider his approach. A friend wrote a Python script to generate C code so the ports of the Butterfly can be toggled. After getting the Butterfly to generate a voltage for every non-white pixel, [Andrew] was impressed with the results so the code was modified determine the brightness of each pixel. The setup managed 10 shades of gray and careful selection of what graphics to post on the build log assured the project a little bit of blog cred.

There are a few ways to display a picture on an oscilloscope, like plugging the Hsync and Vsync into the inputs of a scope. Except for a few music visualizations, we haven’t seen a scope display generated from a microcontroller. Great work [Andrew], but we’d like to mention there’s a grayscale Hack a Day logo from way back when.

Check out a video of [Andrew]’s oscilloscope after the break.

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Xoscillo Turns Arduino In An Oscilloscope

May 21, 2011 by Mike Szczys 11 Comments

If you don’t have an oscilloscope you’d be surprised how many times you find yourself needing one. But if you have an Arduino on hand, the next time you might be able to get by with this software suite that can use a development board as oscilloscope inputs. The project is called xoscillo, and it allows an Arduino, or a Parallax USB Oscilloscope, to probe the signals while a computer does the heavy lifting.

The Arduino can be used for up to four input channels at 7 kHz. It’s possible to probe seven signals at 4 kHz as well. But the main feature that caught our eye is the ability to use several Arduino boards at one time in increase the number of channels available to you.

Granted, this is pretty slow for many digital electronic troubleshooting needs. But at least it’s something you can pull out when you just don’t have any other ideas about what is going wrong with your prototype circuit. We’re sure that sooner or later you’ll break down and buy a proper hackable oscilloscope. After all, your Arduino is probably already occupied as an I2C sniffer.

[Thanks Adam]

Quick Hack Disables IPod Dock Auto-standby

May 2, 2011 by Mike Nathan 11 Comments

ipod_dock_hacking

[Aaron] wrote in to share with us a quick hack that has made his life a little easier. He bought a Rocketfish RF-HV3 portable iPod dock to listen to his music, but he wanted to utilize it as an alarm clock as well. He also found that the speakers worked quite well when he hooked up his Yaesu handheld transmitter to the dock.

The only problem he had with it was that the dock would automatically power down when there was no input for 5 minutes. That’s fine when the dock is running on batteries, but if [Aaron] was going to use it as an alarm clock or to listen to his HAM radio, that simply wouldn’t do.

He pulled the dock apart and started poking around with his DSO Nano scope. He found that if pin 16 stays low for 5 minutes, it turns off the dock even if there is a signal coming through. His fix for the problem was actually quite simple – all he did was solder the VDD pin to the pin in question, and the 5-minute timeout was disabled.

We’re glad that [Aaron] was able to solve his problem in such an easy manner – it just goes to show what you can do with a scope and a few minutes’ time.

Oscilloscope Piano Tuning 101

April 17, 2011 by Jason Komp 10 Comments

[Todd Harrison] recently wrote in to tip us off on his submission to the Tektronix oscilloscope contest – using a scope to tune a piano. In his video he demonstrates how a Fast Fourier Transform can be used to determine the fundamental frequency of the note being played. This is a quick and easy way to determine if that key is in tune, and if not, how far off it is from the desired frequency and in which direction.

He goes on to explain that a scope can only be used as a starting reference point since “mathematically correct” tuning on a piano doesn’t sound right to the human ear. It turns out that when struck, the stretched wires in the piano behave less than ideally. In the case of a piano, the overtones (the other peaks shown on the scope higher in frequency than the fundamental) are actually slightly sharper (higher in frequency) than the expected harmonic whole-number multiple of the fundamental frequency. As a result, the frequency ranges of each octave must be “stretched” in order to accommodate this and sound correct when multiple notes are played together across octaves.

Typically, only the A4 key is actually tuned to its correct frequency of 440Hz and all of the other keys are manually tuned off of this baseline. The amount of necessary stretch applied to each octave increases as you get further away from this initial reference point in either direction and is unique to each and every individual instrument – thus there is no universal device capable of perfect tuning. Although [Todd] admits that he won’t attempt to tune the entire piano himself using this technique, he finds it a convenient way to keep the most heavily played center sections of the piano closer to true between professional tunings.

If you have any interesting or unique uses for your Techtronix scope, you can enter the contest here. Just don’t forget to tip us off too! Thanks [Todd]!

Analog Scope Stands In To For Laser Light Show

April 14, 2011 by Mike Szczys 6 Comments

[Joey] likes to dabble in laser projection, building his own hardware and writing the software that drives it. One way that he tests his setup is by replacing the laser assembly with an analog oscilloscope. This allows him to ensure that the driver board is receiving data from the software, and translating it into the correct electrical signals to drive the motors controlling the mirrored redirection of the laser beam.

In the video linked above [Joey] walks us through this process. It starts by connecting scope probes to the digital-analog-converter card that outputs image data for the projector. From there the XY mode is used to map the two channels perpendicular to each other; the motors that these signals are meant to control have mirrors that also move perpendicular to one another. After adjusting the scale and the timebase you will see the pattern the laser dot is meant to trace.

[Joey] entered this in a Tectronix contest. There’s plenty of other interesting entries to browse though. If have an entry that you’d like to see featured, or if you come across any other interesting stuff, don’t forget to tip us off.

New, Inexpensive DSO Now Shipping

April 12, 2011 by Jeff Katz 24 Comments

Seeed Studio’s line of hacker-friendly tools has expanded by one, they’ve announced that beta units of their DSO Quad oscilloscope are now available for shipping. The DSO Quad is about the size of a thick iPod yet packs impressive features such as two 72MSPS analog channels and a signal generator. By far the coolest ‘feature’ of the DSO Quad is that it’s completely open source.

DSO Quad is a pocket size four-channel digital oscilloscope designed “for common electronic engineering tasks.” It’s based on an ARM Cortex M3 that provides 72MSPS analog bandwidth on two channels with an integrated FPGA and a high speed ADC. In addition to the four data acquisition channels (two analog, two digital), the DSO Quad has a signal generator. This lets you put out square, triangle, saw, and sine waves from 10Hz to 1MHz. An internal 2MB USB stick can be used to store sampled data, upgrade the firmware, or run custom programs. Since the device is still in beta, some of the software specifications aren’t firm, but if you’re looking for a relatively inexpensive ‘scope, this could be the one for you. Just bear in mind that for this pre-production run you’re not getting any documentation, so be prepared to be off the reservation and on your own.