That’s exactly what [Kenneth Finnegan] figured out with his original investigation into low powered MSP430-based circuits. He was able to keep a count-up timer running off of 20F worth of capacitors for over 10 weeks. Although quite impressive by its own merit, many people left comments that questioned whether similar results would be seen in a circuit with functionality more advanced than simply incrementing a single digit on an LCD. Well folks, [Kenneth] has stepped it up again with this ultra low power LCD clock.
The biggest challenge in creating this clock was finding an efficient way to drive the 28 LCD segments off of the limited number of pins on his MSP430G2231 chip while still having open pins for button inputs as well. An ICM7211 LCD driver is definitely up for the task (with a few clever modifications to drive the auxiliary characters such as the center colon), but requires 8 pins to drive it. A standard 74HC595 latching shift register brings this number down to a more manageable number of 3 total pins.
Once completed the total current consumption was found to be around 12μA – low enough for a claimed run-time of approximately two and a half years from the 3V 200mAh CR2032 coin cell used. If true, a set of standard AA alkaline cells in series as found in many clocks would run this little circuit for decades.
Stick around for a short video after the break and make sure to check out the original blog entry for schematics and the complete source code!
Continue reading “How Low Can You Go?”
[Kenneth] and [Jeff] spent a weekend building a cloud chamber. This is a detection device for radiation particles that are constantly bombarding the earth. It works by creating an environment of supersaturated alcohol vapor which condenses when struck by a particle travelling through the container, leaving a wispy trail behind. This was done on the cheap, using isopropyl alcohol and dry ice. They already had a beaker, and after a few tries figured out that the dry ice worked best when serving as a bed for the flask. A black piece of paper was added inside the base of the container to help raise the contrast when looking for condensate. They experimented with a couple of different methods for warming the alcohol, including an immersion heater built from power resistors.
There’s a video explaining the apparatus which we’ve embedded after the break. It’s a bit hard to see evidence of particle travel in the video but that’s all the more reason you should give this a try yourself.
Continue reading “Your very own cloud chamber”
The Chumby One has an internal SD card offering a fair amount of storage. [Kenneth Finnegan’s] came with a 1 GB card that had about 500 MB left over which he filled with a collection of MP3s. But he wanted to do more and so installed a pre-compiled version of lighttpd to act as a web server. The problem is that this binary requires a thumb drive to be plugged in because it maps the storage directory to the mounted USB folder. He wasn’t happy with that so he upgraded the internal SD card and rolled his own webserver to run from the internal SD card.
The upgrade involved going from a 1 GB to an 8 GB microSD card. In order to run the webserver internally he needed to recompile lighttpd to use a different root directory. This meant setting up an ARM cross-compiler and eventually finding a new place for the start up script. The location change for the ‘lighty’ directory leaves us wondering if a symlink couldn’t have solve the problem without recompilation. But we don’t have the hardware on hand to try this out ourselves.
But if you want to give it a shot, check out [Bunnie’s] post about Chumby-based hardware. Looks like you can head out to the big-box store and have one in hand without shelling out too many clams.
We’ve all known the MSP430s under the Launchpad are designed to be low power, but who wants to bet how long the chip can last on only 20F worth of capacitors? A couple of hours? A day at max? [Kenneth Finnegan] setup a MSP430 with supercaps to find out. To make sure the chip is actually running, [Kenneth] programmed it to count from 0 to 9 over a period of 10 seconds, and then reset. To get it ultra low power, the chip is in sleep mode most of the time, and a raw low current LCD is used to display the output. While [Kenneth] simply checks the chip every few hours to see if it’s still counting, a setup much like the Flash Destroyer, tracking a clock and then storing the current value would get a more exact time of death. Either way, it’s been over 3 weeks…and still counting. Video after the rift.
Continue reading “Launchpad takes ultra low power to the extreme”
[Kenneth Finnegan’s] latest clock makes use of the TI Launchpad for programming and debugging MSP430 microprocessors. We took a look at the Launchpad when it was released and we’re glad to see some hacks resulting from availability of that tool. The clock reads out the time using a bi-color LED. Press the button and a series of flashes will tell you the time. A three-position toggle switch is used along with the push button for setting the time. The protocol he developed is outlined in his demo video after the break.
We like [Kenneth’s] use of a plastic electrical box as a project box. They’re cheap and you can find them everywhere in many different sizes. He mentions the difficulty in drilling through the faceplate. We’ve had our share of shattered plastic trying to drill holes in the darn things. If you’ve got some tips on faceplate-modification we’d love to hear them.
This clock is sure the polar opposite from the TTL clock that [Kenneth] showed us back in March, trading jumper wires for lines of code. We’re going to give this one a try, hopefully fixing the button debounce along the way.
Continue reading “MSP430 based single LED clock”
[Kenneth Finnegan] is back with another video showing some cool stuff he’s doing to connect his microcontrollers to the internet. Usually, we see this done with a prebuilt module like an iobridge. [Kenneth] is using a Microchip ENC28j60 module for the communication and he’s managed to stuff it all onto a tiny Electroboards piece. [Kenneth] is starting to become a regular around here.
We’ll just say, [Kenneth] really likes clocks. His most recent is a pure 7400 series TTL based one, ie no microcontroller as seen in the past, here, here, and here. The signal starts out as a typical 32,768 crystal divided down to the necessary 1Hz, which is then divided again appropriately to provide hours and minutes.
As far as TTL clocks go, this is nothing too original; until it comes to his creative button interface. By using a not as sexy as it sounds multivibrator, he can produce a clean square wave instead of the figity signals produced from buttons to advance and set the time. Like always, he also provides us with a thorough breakdown of his clock, after the jump. Continue reading “Pure TTL based clock”