The V-USB library is a pretty handy piece of code that lets you add USB connectivity to ATtiny microcontrollers (it was previously named tinyUSB). But if you’ve ever looked into adding the library to your own projects you may have been stymied by the complexity of the code. There are many examples, but there’s a lack of a concise quick-start for the uninitiated. [Joonas Pihlajamaa] has been working to correct that shortfall with his four-part V-USB tutorial series. It’s not for the absolute newbie; you should already be comfortable working with AVR chips but that’s the only real prerequisite we can see.

He starts the series with a look into the hardware considerations. USB provides a 5V power rail but the data lines expect 3.3V logic so this must be accounted for. With the test rig built on a breadboard he moves on to pick apart the code, covering various user-defined variables that you’ll need to set based on your project’s needs. We’re going to keep this on the back burner and hopefully the Troll Sniffing Rat will get a makeover (although we must say comments have been a lot nicer as of late… keep it up!).

We’ve embedded links to all four tutorial parts after the break.

• http://codeandlife.com/2012/01/22/avr-attiny-usb-tutorial-part-1/ (primer)
• http://codeandlife.com/2012/01/25/avr-attiny-usb-tutorial-part-2/ (hardware)
• http://codeandlife.com/2012/01/29/avr-attiny-usb-tutorial-part-3/ (software)
• http://codeandlife.com/2012/02/04/avr-attiny-usb-tutorial-part-4/ (wrapping up)

If you’re just getting into hobby electronics chances are there are lots of tools you’d like to get you hands on but can’t yet justify the purchases. Why not build some of the simpler ones? Here’s a great example of a 4-channel logic analyzer that can be your next project and will add to your arsenal for future endeavors.

As you can see, [Vassilis'] creation uses a cellphone-sized LCD screen as the output. It is powered by four rechargeable batteries and driven by an ATmega8 microcontroller. He’s designed the tool without power regulation, relying on the ATmega’s rather wide range of operating voltages, and a few diodes to step down that voltage for the LCD screen.

As you can see in the clip after the break, alligator leads can be used to connect the test circuit to the inputs (don’t forget the ground reference!). Thee buttons at the bottom let you navigate the captured data by panning and zooming. Perhaps the best design feature is the single-sided circuit board which should be quite easy to reproduce at home.

[via Dangerous Prototypes]

[Sprite_TM] was tapped to build a rather large quiz buzzer system. Judging from his past work we’re not surprised that he seemed to have no trouble fulfilling the request. As the system is not likely to be used again (or rarely if it is) he found a way to finish the project that was both quick and inexpensive.

Each buzzer consists of a base, a button (both mechanical and electrical), and a couple of LEDs to indicate who buzzed in first. The mechanical part of the button uses a plastic bowl from Ikea and a wooden dowel surrounded by some pipe insulation. A momentary push switch is glued on the top of that dowel, and the insulation projects above that just a bit. This way it acts as a spring. The Dowel has been sized so that the bowl lip will hit the wooden base just as it clicks the switch.

As you can see, all of the buzzers are interlinked using Ethernet cable. The real trick here is how to read 14 buttons using just one CAT5 cable. This is done with the clever use of a 4×4 button matrix for a total of 16 buttons. The matrix also includes the LEDs for each buzzer. Since CAT5 has four twisted pairs this works out perfectly.

Looking for a more robust system thank this? Here’s a pretty nice one.

Reading from a large number of inputs, like this piano keyboard, can be tedious. Even when multiplexing there’s a lot to keep track of. But if you choose the right microcontroller, you may have hardware assistance. Here’s an ATmega640 is using it’s external memory interface to read the key matrix.

You may remember the Open Music Labs article about reading from a shift register using just one pin of a microcontroller. This time around a shift register is still used, but instead of pulling in a long line of parallel inputs, the switches are multiplexed to reduce the number of I/O pins used to read them.

A 74HC573 is used to facilitate the multiplexing. We won’t go into how that part is accomplished; there’s a separate post that explains the process. What’s unique here is that the XMEM peripheral of the AVR microcontroller is used to grab the data. This is intended for external memory chips, but if you get the timing just right, it greatly simplifies reading in a matrix of up to 128 inputs.

[Andrew] is trying to buckle down and hammer out his PhD project but was surprised by the sorry state of the configuration options for his FPGA/ARM dev board. Using JTAG was painfully slow, so he studied the datasheet to see if there was another way. It turns out the Xilinx FPGA he’s using does have a slave serial mode so he came up with a way to push configuration from the ARM to the FPGA serially.

Four of the connects he needed were already mapped to PortC pins on the AT91SAM9260 ARM System on a Chip. He ended up using the EN_GSM pin on the FPGA, since there is no GSM module on this board; connecting it to the microcontroller with a piece of wire. Now he can SSH into the ARM processor, grabbing information on the FPGA from /dev/fpga0. When it comes time to program, it’s as easy as using the cat command on the binary file and redirecting the output to the same hook.

Looks like the Lightweight USB Framework for AVRs (LUFA) has just been ported for ARM microcontrollers. NXP recently released a package for their LPC Cortex M3 family of ARM controllers. You won’t find a reference to LUFA on their nxpUSBlib description page (which we think is kind of sad), but if you grab a copy of the beta code the Version.h header file shows that it is indeed a port of the project. This is further backed up by the LUFA creator, [Dean Camera], who consulted with the NXP team doing the work.

The package provides an open-source USB stack that you can use in your projects as a USB host or USB device. We’re advocates of open source packages like this one as it makes it much easier for hobbyists to get help using the tools, and it allows the community to give back through bug fixes and feature additions.

We’ve highlighted a few LUFA projects, like this keyboard remapper and this AVR programmer. We’re looking to seeing the first set of NXP LUFA projects roll through!

[Thanks Johnny]

[Christopher] found a way to get a bit more mileage out of his TV-B-Gone kit. The little device is intended to turn off every television in range with the push of a button. But at its core it’s really just a microcontroller connected to some infrared LEDs. Instead of sending codes to shut of televisions, you can rewrite the firmware to send a camera remote shutter release code.

It doesn’t take too much to pull this off. You need a way to flash new firmware to the device, and you need to know the new code timing that you want to send. Since the firmware is open source it’s easy enough to make code changes, and there are several easy methods of flashing AVR devices (like the tiny85 used here), including using an Arduino as an ISP.

But [Christopher] did more than just add the Nikon code for his camera. He realized that there’s a jumper to select between European or American television codes. Since he wasn’t using the foreign option, he replace that pin header with a switch that selects between normal TV-B-Gone operation and camera shutter release modes. Nice.

[Mark] had seen a few examples of algorithmic music generation that takes some simple code and produces complex-sounding results. Apparently it’s possible to pipe the output of code like this directly to audio devices on a Linux box, but [Mark] decided to go a different direction. His project lets you play simple algorithms as audio using AVR microcontrollers.

Now the code work for this is very simple, but he hardware implementation is where things get interesting. Ostensibly, [Mark] didn’t have the components available to build a filter to use PWM as an audio signal. Being that he’s a ham operator, he grabbed some radio equipment he had on hand and whipped up an alternative. He’s feeding the PWM from an Arduino into the voltage controlled oscillator on a board meant for high-altitude balloon telemetry. The signal broadcast by this board is then picked up by his radio receiver, and played on some speakers.

Rube-Goldberg contraptions aside, the effect is pretty interesting, as you can hear in the latter half of the video clip which we’ve embedded after the jump.

[Quinn] over at Blondihacks has been working with AVR microcontrollers a lot recently, and wanted a quick way to program the ATtiny13a (her current AVR of choice) while the chip is still seated in a breadboard.

To speed up code revision and testing, she built a small programming header that she calls the Bread Head. The device is wonderfully simplistic, consisting of little more than snappable header pins and a bit of upside-down protoboard.

She soldered six headers to the top (formerly the bottom) side of the board, while a set of eight oversized headers were soldered to the opposite side of the programmer. Small bits of wire were soldered in to connect all of the appropriate pins together before [Quinn] slipped the header snugly over the top of the ATtiny and gave it a quick test. Everything worked perfectly, so she slathered in in epoxy for sturdiness and called it a day.

She says that the programmer works so well that she’s likely to make a similar header for other common AVRs too.

[MakingThingsWork] wanted an accurate way to keep track of the weight of his beehive, so he decided to build himself a data logging electronic scale. First he ripped the strain gauges from an old electronic scale which he then fitted to his home made beehive base. He then went about designing and building the control board which is based about the Attiny 85 (if you hadn’t guessed by the banner). An instrumentation amplifier was used to amplify the signal from the strain gauge, which is then read by the ADC on the Attiny. It looks like he had some trouble getting consistent results from the scale, so to eliminate the error caused by temperature variations he set up a fixed voltage divider for reference. With this setup the scale can produce results at +/- 0.5lb accuracy, sounds just fine for a system that cost less than $50. The V-usb project software has been used to connect the scale to his PC which he uses to collect and graph the data. All in all a very neat project and by the looks of it, some very productive bees.

[Clifford Wolf] wrote in to let us know about a project he recently completed called EmbedVM. It’s a virtual machine for AVR microcontrollers. The package has a relatively small overhead, taking up about 3kB of program memory. The VM can execute 74,000 instructions per second, and runs asynchronously from the microcontroller. As [Clifford] demonstrates in the videos after the break, this can be handy for preloading commands to prevent slowdown during heavy VM processor loads.

The snippet in the image above is an example program written in the C-like VM code which will play some [Rick Astley] on a speaker. This code can be run from RAM, EEPROM, or even external storage like an SD card. Recently there was a supplemental compiler project that even takes Python code and compiles it into VM byte-code. What a nice abstraction tool for making inexpensive microcontroller-based designs easily programmable for those that have a bit of Python experience.

If you don’t recognize the name, [Clifford Wolf] is also the author of OpenSCAD, a tool that is quite popular with 3D printing.

[jethomson] sent in a build he’s been working on that turns an inexpensive AVR programmer into a development board. The build is based on the very affordable USBasp programmer that’s based on an ATmega8. With hundreds of these boards available from China for less than a Hamilton, we’re wondering how soon it will be before we see these boards end up in other projects.

After fiddling with the AVR fuse settings, [jethomson] managed to burn some code to the microcontroller. After that, all that was required to upload software to the programmer is a bit of solder, a push button, and an external programmer. [jethomson] also managed to make this little AVR programmer compatible with the Arduino environment with a small addition to the boards.txt file.

[jethomson] included a few bits of software as an example – he ported the haunted USB cable and adapted the USB business card to print out, “All work and no play makes Jack a dull boy.” Nice work, and we can’t wait to see it in future projects.

[Malte] is a loyal Hackaday reader and neurobiology PhD candidate with a keen interest in hobby robotics – definitely our kind of guy! He wrote in to share a project he has been working on in his spare time, a Kinect-controlled delta robot (Google translation).

Deltares, as it is called, is pretty straightforward as far as delta robots are concerned. It uses three servos to actuate the arms, which are controlled by an AVR micro running BASCOM. The AVR gets its coordinate data from his computer via a serial connection after it has been captured by the Kinect. [Malte] opted to use Microsoft’s official SDK for the project, processing the Kinect skeletal data using a small C# application he wrote.

The end result is pretty neat as you can see in the pair of videos below. In the first video, [Malte] uses Deltares as a plotter, drawing a crude face on a piece of paper with a marker. In the second, he commands Deltares with his right hand, using his left to activate the magnetic solenoid to pick up the steel spheres.

It looks pretty cool to us, and we’d love to see what sorts of things he puts together if he ever ends up making robotics his career rather than a hobby.

Feeling a bit left out because he didn’t have a PICAXE on hand, [Rob Miles] decided to port the Luna Mod code so that it would work on an AVR chip. He chose to build his around an ATtiny45, but also mentions that this is Arduino compatible.

This case layout is a bit different from the original Make version, but we like this look just a bit better. It might not satisfy your need for that hipster looking enclosure, but the repurposed macadamia nut box looks seems it was built for this purpose. Take a look as the video after the break to see the final product and hear it spewing newly composed cacophony. [Rob] is sharing the sketch as a dropbox file but we’ve also included our own hosted link after the break in case is stops working.

Source Code

Here’s a new option for building your own AVR programmer. It’s called the MkII Slim and the diminutive size makes it live up to its name. The design is rather spartan, using just three chips; a voltage regulator, a MAX3002 level converter, and an Atmel AT90USB162 as the main microcontroller. This chip has a built-in USB module, foregoing the need for a separate FTDI chip.

The firmware is built on the Lightweight USB Framework for AVRs (LUFA). This is a USB stack implementation originally called MyUSB that was developed by [Dean Camera]. Regular lurkers over at the AVRfreaks forums will recognize [Dean's] name, or his handle [abcminiuser] as a source for many of the high quality AVR tutorials found there. But we digress.

The programmer offers all the features you’d want in an In-System Programmer. It can easily be reflashed with future updates thanks to the bootloader running on the chip. There’s jumper-selectable power options, and it can program targets running at 3.3V or 5v. The full development package including code and artwork is available for download at the site linked above. For your convenience we’ve embedded the schematic after the break.