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Posts posted by rebeltaz

  1. I finally desined a board that I need more than one of and I thought I'd give Elecrow a try. When I tried to add the 5-pc 10cmx10cm board service to the cart, I got a Page Not Found error. So I tried to shoot them a message from their on-line support form and got the same error page. I was just wondering if anyone else has used them succefully recently or received the same error pages?


    Thanks guys :)

  2. Nice design and execution.


    I notice there is a coin cell, and what looks like an external power connector.

    Am I right in assuming that the MSP430 is powered via the coin cell when the external power is cut to maintain time. and the LEDs only run off external power?


    Than you :)


    And yes... when the external power is cut, the coin cell takes over and the MSP ceases updating the display, while still maintaining the current time. So far, it seems to be working pretty well :)

  3. @@enl -> This is the circuit I am using in the rest of the clock to switch the common anode segment displays:




    It works, but I can't implement that with my idea of toggling positive and negative on the same pin.


    @@abecedarian -> I like that switch, but looking at the datasheet, it looks like I would still need to have it switch between two transistors (since it can't handle more than 50ma by itself or Vss (the switched voltage) higher than Vdd. And if I were to run Vdd high enough to allow switching of 12v, then I'd need to switch the input of the switch IC with another transistor... and this is just getting complicated!  lol...


    It is beginning to look like the simplest solution is just to go ahead and use the two remaining output pins. Or, I guess even easier would be to just use a small SPDT mechanical relay.


    Thanks, though guys :)

  4. I am trying to toggle a set of LEDs. I have two pins left available to use, but I would really rather not use both for this one feature if I can help it. I'd like to have a spare pin left over in case I need it later. What I am trying to do is to drive the MSP output positive to select one set of LEDs and negative to select the other set. Will this work without burning out the output pin? Or will the MSP even be able to pull the PNP base to ground far enough to turn it on? Usually, when switching PNP transistors with 12v on the emitter, I typically switch an NPN with the MSP and use that to bring the base to ground, but obviously (or so it seems to me anyway) I can't do that in this situation.




    Thanks as usual :)

  5. You could add illumination below the moon and sun to indicate nighttime and daytime. Or even fancier: light them at sunrise and moonrise, you could even do the moon segmented and show the current phase of the moon on it.

    There is a little tool on some unix systems called "pom", which stand for phase of moon. You could use the code in that to calculate these things.


    Oh man... it's so cool that you said that! That actually was in my original design plans (lighting the sun or moon to show AM or PM) but since the plastic sheet is blue, I was afraid the the sun might shine green if I tried to illuminate it! I may try that later though.


    I also thought about adding stars using fiber optics. My projects are never finished so... :)

  6. Ok... so compared to some of the projects I see on here, I feel like amateur hour at the Apollo, but.... Here goes:


    I love building clocks, but I have no use for time itself. So a long time ago, I thought of doing this project. It wasn't until I fell in love with the MSP430 that I dusted it off and got to it. I call this piece "Beyond Time & Space."  It is 12"x24" and every bit is custom built and hand painted.


    I would love to be able to post this to Etsy or something and sell a few, but with what I have in this, both in materials and time, I'd have to charge close to $600 for it and I doubt anyone would be willing to pay that :D


    I need to get better pictures of the actual finished product, but I enjoy it and I hope you guys do, too!



  7. In case anyone else would like to play around with really large displays, I found these - http://www.seeedstudio.com/depot/LED-Segment-c-34_78/?terms_id=216&ref=crumb - They sell 8", 5" and 3" displays for less than $10 each (only $3.50 for the 3" displays), but they are only in red and green. I guess you make make a Christmas countdown clock :)


    I did find the blue displays on eBay - http://www.ebay.com/itm/310610985717 - for only $35 for a set of five.


    Just thought I'd share that in case someone else might want a set for Christmas :)

  8. I just wanted to let everyone know, in case any one else runs into this, that I got this working. I removed R23 from the circuit, left D2 as a 1n4148 and replaced D1 with an unknown rectifier that I found in my junk box with a voltage drop of about .168v. I also modified the code to incorporate a power good line to disable scanning if the main power is lost. Works great! Thanks for all y'alls help!

  9. Few suggestions.

    Use one of the spare pins on MSP430 to detect power down. When there's no power, do not scan (set P1.0-P1.4 to low.) This will save you a lot of mA when powered from the battery.

    Increase base resistor values (R2, R15-R18,) 2k2 or 4k7 for example.

    I would also add 1uF and 0.1uF cap to MSP's Vcc and 1nF to RST (power spikes could be resetting your MCU.)


    I actually had thought about detecting power down and disabling the scan, but I wasn't sure how much current that would save. I may try that.


    For some reason, tonight I was able to get the msp to run using two AA batteries in place of the cr2032 and jumping the resistor out completely. Then for some unknown reason, the msp actually ran on the cr2032 when I went back to that, but I think all of this testing has drained it because it kept dipping below 1.8v so I need to replace that, but... I have another question.


    How far below the main power supply does the battery voltage have to be to ensure that the clock runs off the 78l33 and not the battery? I am going to have to decrease that resistor and see if I can't find a couple of germanium diodes in my junk box, as @@Foghorn suggested.

  10. Well, I did connect the battery directly to the junction of D1 and D2, bypassing R23 and D2 and it still won't run the processor, so... Backtracking one step at a time is usually how I track down idiosyncrasies, but in this case, it just is not making logical sense and there is no where to back track from since I can't get the processor to run off the battery at all.

  11. sigh.... this doesn't make any sense. I disconnected the 78L33 from D1, plugged the 12v AC adapter in and powered the MSP from the battery. Nothing... well, maybe a VERY dim flicker of a couple of the LEDs.


    What is REALLY odd are the voltages. Powering the circuit with 78L33, voltage on the 3.3v line (Vss and RST) is 2.6-2.7v. Unplug the AC adapter and measure the battery voltage on the 3.3v line I get 2.0-2.1v. Now that SHOULD be enough to power the processor, but that is not the odd part. If I jump out the 1.5k resistor (R23- I know it says 10 ohm in the schematic I posted, but that was no where near enough to drop the voltage) in series with the battery, on the 3.3v line I get the same 2.6-2.7v that I get from the 78L33 ... but the processor still doesn't run!?


    I am going to post the complete schematic in case I am overlooking something. I swear I can never have "normal" problems! lol...


  12. Possibly Brown out on unplugging or hot plugging. And why the resistor on the battery? With the diode drops and the cr2032's internal esr its unneeded, the battery should always be less than the regulated 3.3V rail anyway. And what speed are you running the msp430 at? At 2.7V to 2V it should be less than 12mHz.


    I'm only running this at 1MHz. I thought that the battery would be low enough, too, but without the resistor, it's only like 0.05-0.1v below the supply voltage and I didn't think that that was low enough. I even tried adding a 470uf capacitor across the supply pins on the MSP (pins 1 and 20) as well as a 470uF capacitor across the reset pin and ground to help in case the transition wasn't quick enough. Still no good.

  13. You mean disconnect the regulator and power the circuit up as normal, except with the battery powering the MSP in place of the 78L33? No.. I didn't try that. I just measured the voltage on pin1 (VCC) with and without the power supply plugged in. I can try that, though...

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