VGA Video Output With An ATtiny

August 31, 2011 by Mike Nathan 5 Comments

vga_video_attiny

[Fernando] is working on creating a game at home, with live scoring displayed on a large LCD TV. He’s keeping mum as to what the game entails, but he was more than happy to spill the details on how he planned to use the television as a wireless scoreboard.

The writeup is the first part in what will likely be a substantial series of progress reports, covering how he used an ATtiny45 to drive his LCD display. Eventually, the scoreboard will use a Bluetooth adapter for wireless input, but his immediate goal was to get the display running properly.

He explains how he uses the tiny micro and its limited set of I/O pins to drive the display, dipping into some of the technical details along the way. He discusses how he worked out the timings of the VSYNC and HSYNC pulsing, as well as how how the characters are actually drawn on the screen.

The article isn’t overly heavy on the technical details, and he has sample code available so you can take a look at how the VGA magic was done, so be sure to check it out.

Tiny External System Monitor Makes It Easy To Keep Tabs On Your PC

August 2, 2011 by Mike Nathan 13 Comments

tiny_pc_resource_monitor

Instructables user [Jan] likes to keep close tabs on his computer’s memory usage, but wanted something more interesting to look at than the standard resource manager. He preferred to have an external display available that would show his computer’s status with a quick glance, and thus this system monitor was born.

His status panel contains a trio of constantly updated LED bars that show his computer’s CPU usage, available physical memory, and virtual memory consumption. With a small footprint being a priority, [Jan] kept the indicator’s size down by using SMD components and by including an on-board UART to USB converter to go along with his ATTiny microcontroller.

He uses a Python script to gather usage information from his computer, feeding it to his display over USB. The system works pretty well as you can see in the video below, though the virtual memory indicator doesn’t seem to get a ton of action – perhaps it could be used to indicate hard drive activity instead.

If you are looking to build something similar, [Jan] has made all of his code and schematics available for anyone’s use.

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A Study In AVR Power Saving Techniques

July 26, 2011 by Mike Nathan 88 Comments

amtel_avr

[Scott] found the iCufflinks from Adafruit Industries pretty interesting, but he thought that the stated run time of 24 hours was a bit short. He figured he could improve the product’s power consumption at least a little bit, to improve the overall battery life.

From their schematics, he placed an order for parts and built two identical iCufflink mock-ups side by side – one running their code and one running his. He took baseline current draw measurements, then got busy slimming down the cufflinks’ software. It had been 20 years since he touched assembly, and he has never written it for an AVR, but judging by his work he’s not rusty in the least.

He slowed the ATtiny’s clock down and tweaked a few other settings for a savings of 53μA, but the real improvements came via a fairly simple fix. The original code called for the processor to institute a counting loop to sleep, which he found to be very wasteful. Instead, he chose to put the processor in an idle state, using the chip’s watchdog timer to wake it when it was time to pulse the LED. The power savings from this change alone was a whopping 261μA!

When he was said and done, the changes save about 315μA of current draw, and should allow the cufflinks to run for up to 38 hours without swapping batteries. In [Scott’s] opinion, a nearly 60% improvement in battery life is pretty good for a day’s work, and we’re inclined to agree.

Digital Cootie Detector

July 25, 2011 by Brian Benchoff 19 Comments

Kids love games of exclusion. This usually manifests itself in games of ‘keep away,’ having someone ‘catch cooties,’ or the ever-popular ‘No Brian club.’ [Rob] wrote in to tell us about the digital cootie detector he built. The cootie detector operates on galvanic skin response. It’s actually very similar to an E-Meter, although instead of Thetans this device measures something that actually exists.

Galvanic skin response is a measure of the skin’s conductivity. Skin conductivity changes because sweat glands will be activated when someone is nervous. This is a measure of psychological arousal, making it a great detector for games of exclusion – a kid who doesn’t want cooties will ‘psych themself out’ and give themselves cooties.

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Cheap Voice-controlled Lighting

July 15, 2011 by Mike Nathan 9 Comments

voice_controlled_home_automation_board

Voice-controlled home automation doesn’t have to be wildly expensive if you have a little bit of time and some know-how to do the job yourself. [jjshortcut] wanted to control the lighting in his room without using physical switches. On his blog, he describes how he did it without spending a ton of money.

He picked up a VRBot speech recognition module on eBay, which is an easy way to get your feet wet with voice control. The device has a bunch of built-in speaker independent commands, as well as the ability to record up to 32 custom triggers. Rather than mess with mains voltage and build his own light relays, he purchased a simple set of wireless light switches and began hacking.

He spent some time sniffing the wireless communications protocol to figure out how the lights were triggered, then he replicated that functionality using an AVR and a cheap 433 MHz module.

The system seems to work quite well despite how cheaply he was able to put it together. Stick around to see a quick video of his voice recognition system in action.

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Using An AVR As An RFID Tag

May 20, 2011 by Brian Benchoff 11 Comments

A few years ago, [Beth] came up with the idea of using an AVR as an RFID tag. She’s gotten sidetracked with a few other projects in the meantime but her idea has surfaced again, this time as a duct tape RFID tag. The build is just four components: 0.1 µF and 1 nF capacitors, an ATtiny85 microcontroller, and 100 turns of 40 AWG magnet wire, all soldered together and placed on a duct tape substrate.

Like most RFID tags, the power is drawn from the reader through the coil, but even in low power versions the ATtiny is only rated down to 1.8 Volts. Since the microcontroller is only getting about 1 Volt from the coil, the clock oscillator of the ATtiny won’t work. This isn’t a problem in this build, because the coil is connected to the the clock input – the 125 kHz coming off the reader provides the clock. Very clever.

Of course, the microcontroller is going to need some firmware to send some bits to the reader, so she used the AVRFID firmware (check out the comments in the source for a great walkthrough) to transmit under the HID protocol, itself a derivative of [Beth]’s earlier work with the EM4102 protocol.

Not only are we impressed with this hack, we’re amazed [Beth] is still perfecting her work more than two years after her first post on the subject. That’s dedication and unbridled cleverness.

Via adafruit

USB Geiger Counter Hack

May 13, 2011 by Mike Nathan 17 Comments

usb_geiger

[Vic] bought a Kvarts DRSB-01 Geiger counter a few years ago, and recently dug it out of his electronics stash. The counter is a run of the mil no-frills unit. It lacks any kind of LCD display and it cannot be calibrated, so Sievert exposure ratings are out of the question. The unit essentially monitors background radiation and alerts the user to the presence of gamma and high-energy beta rays via audible clicks.

[Vic] wanted to make it a bit more useful, so he decided to interface it with his computer in order to take long-term radiation measurements. He dug up a schematic online and deadbugged a small circuit using an ATtiny44. The circuit allows him to enumerate the electrical pulses generated by ionizing particles striking the Geiger tube, passing them along to his PC over USB.

The counter seems to interface with the PC just fine, but [Vic] does say that he’s getting some odd readings. He thinks that he might have damaged the tube while messing around, but he’s all ears if you have any insight on the matter.