I was never suggesting that a series resistor was not needed. Normally I use something between 100 Ohm and 1K.While it may work, as a general rule NEVER drive a LED directly from a microcontroller port.
Controlling a led, pull up resistor value
- danicampora
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Re: Controlling a led, pull up resistor value
Re: Controlling a led, pull up resistor value
@bmarkus @danicampora:
Then I read the part about using a series resistor. Yes, always use a series resistor
-Bryan
My first thought on reading this was "wait a minute, why not? I've put something like 10K boards of various designs into production doing exactly that!"bmarkus wrote:While it may work, as a general rule NEVER drive a LED directly from a microcontroller port.
Then I read the part about using a series resistor. Yes, always use a series resistor
![Laughing :lol:](./images/smilies/icon_lol.gif)
-Bryan
Re: Controlling a led, pull up resistor value
If using a Blue LED I have measured Vf at 2.7Volts (quite a bit higher than the Red/Orange/Yellow) and I believe white are similar to blue.
For Blue LED
(3.3-2.7)/0.005 = 120ohms min R required to draw max GPIO current
That said using a 330ohm with Blue LED which in this case would draw 1.8mA to me is bright enough
For Blue LED
(3.3-2.7)/0.005 = 120ohms min R required to draw max GPIO current
That said using a 330ohm with Blue LED which in this case would draw 1.8mA to me is bright enough