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what is difference when we connect resister b/w fpga and led,
And Fpga is directly connected with led then pull down? Regards, shahulLink Copied
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use resister can reduce the current and the brightness of the led.
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please reply to the above question?
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I don't understand your question... putting the resistors before or after the leds doesn't change anything, as in both cases they are in series with the leds.
But with 10k I don't think that you'll see a lot. Just check the LED datasheet for the recommended current and standard forward voltage, and determine the nominal value for your resistors.- Mark as New
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Hi Daixiwen,
why i ask this question is in our FPGA we have 8 leds connected as the top schematics shown in that figure.At the time of power ON all led glow. I don't no why this leds are glowing.it should be in off state. Regards, shahul- Mark as New
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Before configuration all the pins have a weak pull-up, so this can explain why you see them glowing. It should be a lot dimmer than with an output pin at logical '1' though.
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Mostly, people are operating LEDs with active low FPGA outputs and anode connected to 3.3V for the said reason.
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