MSP430 based single LED clock

[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.

62 thoughts on “MSP430 based single LED clock

  1. solution: soldering iron.

    wtf is wrong with you noobs?

    for _any_ thermoplastic, IM or not, you just get your cheapest 15W – 30W soldering iron and push through and you get exactly the whole you need.

    You don’t want to share tips between solder and plastic, and you don’t want to breathe the fumes, but that’s all; it’s a fantastic way of working any thermoplastic — you’ll see, you sorta turn it into putty. in fact when you get good at it you can actually soften it and work it with your hands, or ‘braze’ pieces together, or reinforce something…

    And in many cases you can harvest the raw materials you need for adding or making case modifications from really random places. Once I used a black grommet from a table to connect two halves of a parallel printer sharing box that went on to become my doom light (google image search for “doom light fruzzetti”).

    using soldering irons for thermoplastics makes me elite, as long as i don’t let myself breathe the fumes — and as long as i remember 30W is pretty much the HOTTEST i should use.


  2. if you push the soldering iron in from the side that will be the EXTERIOR you’ll get the better look; in my experience i was able to quickly learn a technique that made excellent holes and another technique for reaming small holes.

    use a razor blade to cut off the excess AFTER IT COOLS and you’ll be super-happy.

  3. I can’t imagine melting the plastic will generate very nice or precise holes. The plastic also smells AWFUL when I did melt it just for the centering hole, and discolored a large region around it. Thanks for letting us all know how little we know though, Dan. I’ll plan accordingly.

  4. For faceplate drilling, I second several earlier comments: drill press (or hole jig if you don’t have a press); flat something beneath (hardwood or softwood works great), brad point bits (less material is being chewed up) or 1/8″ pilot hole and forstner bits, SLOW and steady with consistent light pressure (especially with brad point). It’s really putting too much downward force on the bit that causes the cracks, so you might see more cracking if your drill has a hammer action. High speed works too, but can leave chips at the hole edges and tends to melt the material which is unsafe if no clamp is used. Those edges are quite sharp at speed when the plastic melts and then sticks in the flutes of your bit.

    Cheap faceplate alternatives: Thin 1/8 or 1/16 in wood sheet cut to size with two holes drilled for mounting screws. Same thing but using tin snips and thin metal sheet. Thing about re-using that old VCR case you probably have lying around for parts.

  5. bounce solution: “pause” the program for a small time period before continuing your looped code. (easiest solution)

    One micro we made in microprocessor classes:
    after detecting that the push button was pushed down, we had a time frame the clicker was known to take (added quite a few micro seconds) we waited for the button to be released (since humans are incapable of letting go before its done bouncing) and when it was released that was the time to say, “oh hey, he/she pushed the button”
    also, there are simpler ways like adding a capacitor so that the voltage never drops below 3.6V (usually the lowest value acceptable for a “high”)

    Hope I helped

  6. another way is to use blutak, a press drill and water to make a primitive cooled drilling rig.. works well but don’t use it on toughened glass.
    also advisable to anneal it afterwards with a bunsen or small blowlamp to stop it fracturing later.

  7. @Craig O’Connor: There is no looped code; the entire system is only interrupt and interrupt-service based, so a busy loop would be a detractor from the system. The solution I’m considering is disabling the port interrupt, then setting a timer interrupt for some timer period in the future, then using that interrupt to reenable the port interrupt. This is essentially “pausing” the code, in that the int for the button is disabled for, say, 250ms, but the processor is still asleep for those 250ms, which is important for battery life.

  8. For the faceplate – look for the ‘unbreakable’ nylon plates instead of the regular plastic ones. The recommendations about using a drill press and tape still stand. Use a sharp bit and go slow. I clamp the plates in my drill press vise and let the bit do the cutting, advancing it very slowly. It takes some effort to get the speed right – too fast and you end up messing up the plate. Too slow and you melt the plastic. The key is using the unbreakable nylon plates. At least that is what works for me. These can be found at most home centers. I get mine at Lowe’s.

  9. I don’t understand why there is all this rhetoric and hand wringing about drilling holes in thin plastic, or any other thin material for that matter. The commonly available step bit, such as a Unibit, was purpose designed to enable anyone to cheaply, easily, and quickly drill perfectly round holes in thin material without cracking or chipping or breaking or grabbing or anything else exciting. It just a boring tool (pun intended). Works in aluminum just as well as plastic and will even drill circuit board material, although the G4 stuff will dull the bit after a bunch of holes. On the upside, the bit has only one cutting edge that can easily be sharpened with a Dremel. Get a Unibit and the problem is gone, forever. No toxic fumes, no need to back up with wood, no need to do anything other than drill the dang hole. Simple!

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