roadrunner84 466 Posted November 5, 2012 Share Posted November 5, 2012 Hi all, I am working on a project which uses 2 x (6 LEDs charlieplexed on 3 I/O lines). I chose for this setup instead of 12 LEDs on 4 I/O lines to up the dutycycle from 1/12th to 1/6th, hoping to increase the brightness. My timer ticks at 512Hz, so in 6/512 seconds all LEDs are cycled and the sequence starts over. The software is working fine, the LEDs are lit.... that is, when I turn off all the lights in the room I can berely discriminate lit from unlit. The LEDs shine so dim it's almost not noticable. I chose red LEDs, because they need the least voltage of all (only 1.8V). For now, I do not use any series resistor. I know the Lauchpad supplies 3.6 volts to the MSP430G2211, the datasheet is somewhat cryptic on that matter. The datasheet says that at a load of 6mA per pin (the total load of 48mA) VoutHi >= Vcc - 0.3V and VoutLow <= Vdd + 0.3V. Now I'm not sure what to make of that, but I think the MSP430 does not supply enough current for my application. I have seen several charlieplexing projects, also on the MSP430. How come my LEDs barely shine at all? What should do the trick? Thanks, roadrunner. Quote Link to post Share on other sites
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