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rockets4kids

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  1. Like
    rockets4kids got a reaction from tripwire in Reversing the LED? i.e. sinking it to MCU?   
    At this point it is worth noting that the forward voltage drop of blue (and phosphor-colored LEDs driven by blue or UV elements) is typically close to that of the operating voltage of the msp430.  When you factor in the voltage droop of loaded MSP430 pins, you'll get some some degree of current limiting even when connecting one of these LEDs without a resistor.
     
    But again, just because this works (and you may find other people doing it) doesn't mean you should do it unless you fully understand what is going on.
  2. Like
    rockets4kids got a reaction from igor in Reversing the LED? i.e. sinking it to MCU?   
    In the olden days -- long, long ago -- the final drive circuitry for many logic parts could source more current than it could sink.  In most cases with modern parts this is no longer the case.
     
    You can always find specifications in the datasheet.  If you cannot find them, you are looking in the wrong datasheet.  Always be careful when only a single value is specified -- pay attention to what that number means!  In some cases, that is the limit to what the chip can take without damage.  In others, it is the limit to which it can maintain the proper output voltage levels.
     
    For some parts (such as the msp430) you will not find per-pin limits.  When this is as case, you will find a graph that shows the output voltage with respect to current.  Pay particular attention to how little current the msp430 parts can source/sink before the voltage levels change.  While the msp430 can only supply about 6 mA per pin and maintain proper logic level voltages (depending on operating voltage) it does seem as if it is safe to drive parts such as LEDs at higher currents when you aren't concerned about output voltage.  That is to say you won't damage your msp430 pin by driving an LED at 20 mA.  However, just because you can do this without damaging the pin doesn't mean you should design a circuit this way.
     
    Finally, be sure to pay attention to the *total* amount of current the chip can supply to all pins.  It is often *much* less than the total current per pin multiplied by the number of pins.
  3. Like
    rockets4kids got a reaction from abc in Reversing the LED? i.e. sinking it to MCU?   
    At this point it is worth noting that the forward voltage drop of blue (and phosphor-colored LEDs driven by blue or UV elements) is typically close to that of the operating voltage of the msp430.  When you factor in the voltage droop of loaded MSP430 pins, you'll get some some degree of current limiting even when connecting one of these LEDs without a resistor.
     
    But again, just because this works (and you may find other people doing it) doesn't mean you should do it unless you fully understand what is going on.
  4. Like
    rockets4kids got a reaction from greeeg in Reversing the LED? i.e. sinking it to MCU?   
    In the olden days -- long, long ago -- the final drive circuitry for many logic parts could source more current than it could sink.  In most cases with modern parts this is no longer the case.
     
    You can always find specifications in the datasheet.  If you cannot find them, you are looking in the wrong datasheet.  Always be careful when only a single value is specified -- pay attention to what that number means!  In some cases, that is the limit to what the chip can take without damage.  In others, it is the limit to which it can maintain the proper output voltage levels.
     
    For some parts (such as the msp430) you will not find per-pin limits.  When this is as case, you will find a graph that shows the output voltage with respect to current.  Pay particular attention to how little current the msp430 parts can source/sink before the voltage levels change.  While the msp430 can only supply about 6 mA per pin and maintain proper logic level voltages (depending on operating voltage) it does seem as if it is safe to drive parts such as LEDs at higher currents when you aren't concerned about output voltage.  That is to say you won't damage your msp430 pin by driving an LED at 20 mA.  However, just because you can do this without damaging the pin doesn't mean you should design a circuit this way.
     
    Finally, be sure to pay attention to the *total* amount of current the chip can supply to all pins.  It is often *much* less than the total current per pin multiplied by the number of pins.
  5. Like
    rockets4kids got a reaction from abc in Turning MSP430 into an amperemeter - possible?   
    http://forum.43oh.com/topic/2351-voltampwatt-meter/
  6. Like
    rockets4kids got a reaction from KatiePier in Teaching Launchpad to Children   
    If you son is comfortable with CCS, let him use it.  Some children raised on computers are not intimidated by a screen full of buttons and menus.
     
    However, be aware that CCS and Energia differ in more than their interface.  Energia uses a library that abstracts away much of the details of the hardware, making it much easier to use for beginners.  But again, so long as your son isn't getting frustrated, let him stay with CCS.
     
    Learning how to program microcontrollers natively (that is, without an abstraction layer like Energia/Arduino) is not intrinsically difficult, but sadly there is very little documentation aimed at absolute beginners.
     
    One book I do highly recommend for anyone really wanting to get into computers is "CODE: The Hidden Language of Computer Hardware and Software" by Charles Petzold.  (http://www.charlespetzold.com/code/)
  7. Like
    rockets4kids got a reaction from bluehash in Wireless frequency meter   
    Here is another thread to read:
     
    http://forum.43oh.com/topic/1913-frequency-counter-using-launchpad-nokia-5110-lcd/
     
    And don't miss this:
     
    http://www.leapsecond.com/pdf/an200.pdf
  8. Like
    rockets4kids got a reaction from bluehash in ULP prefers static variables over local ones, why?   
    Doing so saves you the cycles required to initialie the variables.
     
    The ULP is pretty bogus, IMO.  It will help you shave tiny fractions here and there, but it is completely obvlivious to fundamentally bad design.
  9. Like
    rockets4kids got a reaction from tripwire in Energy use for interrupts   
    One thing to remember when using interrupts on pushbuttons is debouncing.  If you do not disable interrupts for the duration of the bounce period you will get hit with a chain of interrupts that will almost certainly cause problems.
  10. Like
    rockets4kids got a reaction from abc in Energy use for interrupts   
    One thing to remember when using interrupts on pushbuttons is debouncing.  If you do not disable interrupts for the duration of the bounce period you will get hit with a chain of interrupts that will almost certainly cause problems.
  11. Like
    rockets4kids got a reaction from greeeg in Push Button Code Not Working?   
    And that's just fine if you want the LED to flash very rapidly when the buton is pressed and then left in a random state when the button is released.
     
    I do not think that is what OP had in mind.
  12. Like
    rockets4kids got a reaction from basil4j in Optimising math   
    This may be relevant to your interests:
     
    http://home.earthlink.net/~david.schultz/rnd/2004/KalmanApogeeII.pdf
  13. Like
    rockets4kids got a reaction from GeekDoc in Printing PCB, the end of bread board   
    I completely fail to see the interest in any of these conductive inks.  The resistance is so high that they are practically useless, and the issue of joining parts to the ink is greater than any advantage to be gained, even at  much lower resistance levels.  Nevermind the absurd price.
     
    In many ways, the "popularity" of conductive ink is representative of everything I loathe in the maker community -- An expensive and proprietary solution for a problem that simply doesn't exist.
  14. Like
    rockets4kids got a reaction from bluehash in AY-3-8910A sound generator   
    You may enjoy this, too:
     

  15. Like
    rockets4kids got a reaction from enl in AY-3-8910A sound generator   
    You may enjoy this, too:
     

  16. Like
    rockets4kids got a reaction from chicken in Printing PCB, the end of bread board   
    I completely fail to see the interest in any of these conductive inks.  The resistance is so high that they are practically useless, and the issue of joining parts to the ink is greater than any advantage to be gained, even at  much lower resistance levels.  Nevermind the absurd price.
     
    In many ways, the "popularity" of conductive ink is representative of everything I loathe in the maker community -- An expensive and proprietary solution for a problem that simply doesn't exist.
  17. Like
    rockets4kids got a reaction from tushki7 in What is your workplace wall colour?   
    Bright white is always best at making small rooms appear larger and providing the best light to work by.
  18. Like
    rockets4kids reacted to pabigot in Wolverine Launchpad   
    The update replaces the ezfet interface with the same tilib interface used by the FET430UIF, so I don't use the ezfet driver at all anymore.  tilib through the USB interface runs at the same speed as tilib through the FET430UIF.
  19. Like
    rockets4kids got a reaction from dangpzanco in Generating random numbers.   
    Another option I have used in the past where speed and small code size trump all else is a Linear Feedback Shift Register. This is something I learned from Don Lancaster back in the Apple 2 days. His particular recipe can be found here:
     
    http://www.tinaja.com/glib/atg1.pdf
     
    on page 1.1
  20. Like
    rockets4kids got a reaction from dangpzanco in tone generator on MSP430 g2553   
    Are you seriously so lazy that you are not even going to bother to edit the text of your classroom assignment before asking someone else to do it for you?
  21. Like
    rockets4kids got a reaction from supamas in RFP70N06 MOSFET   
    Note that this part has a max gate threshold of 4.0 volts, so it is possible that you are not turning it on fully with with an msp430 running at max voltage.  Set up a test circuit on your breadboard with a potentiometer on the gate and monitor the voltage drop across the MOSFET as you ramp up the gate voltage.
  22. Like
    rockets4kids got a reaction from Rei Vilo in What Information to Provide When Asking for Help   
    Also:
     
    http://www.catb.org/~esr/faqs/smart-questions.html
  23. Like
    rockets4kids got a reaction from G0XAR in [SOLVED] Hitachi character LCD not working with the "Hello World" Energia Sketch   
    The startup timing on these LCDs is very sensitive.  The ones I have seem to be particularly slow (through still in spec) and the timing constants in many libraries cause it to fail like this.  Drove me nuts when I was trying to get one working for the first time.
     
    I don't know anything about the timing in the Energia libs, but you might want to get confirmation on that.
  24. Like
    rockets4kids got a reaction from abecedarian in What Information to Provide When Asking for Help   
    Also:
     
    http://www.catb.org/~esr/faqs/smart-questions.html
  25. Like
    rockets4kids got a reaction from oPossum in RTFM - Read The Fabulous Manual   
    I don't think anyone has questioned the accuracy or veracity of TI's documentation.
     
    I can't speak for others, but I do not use the E2E forums because the software is just so ungodly awful.  I am not a fan of web forums in general, but E2E is just fingers-across-a-chalkboard unpleasant.  I might be inclined to use it if there was good content, but every time I have wound up there as a result of a google search I have never found anything worthwhile.
     
    And again, I still think the main reason more people don't RTFM is simply because they have never actually *found* TFM.
     
    Yes, the family datasheets are 600-odd pages of densely worded text.  There is no doubt that reading them is often difficult.  That is par for the course when working with microcontrollers.
     
    There is indeed a huge gap between TI's introductory material and the datasheets.  I have stated time and time again that if TI wants the Launchpad to be a useful educational tool, they should do a better job of bridging that documentation gap.
     
    Unfortunately, it is now clear that TI has chosen instead to devote it's resources to Energia.  I think this is a terrible decision for a whole host of reasons, but mostly because it obscures how the chips actually work rather than teaching how they do work.  What makes this sadder still is is that the MSP430 is far and away the best architecture to learn using microcontrollers natively. 
     
    And if Energia truly is the future, for better or worse, it is sad that TI would do such a poor job at fostering the community supporting it.
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