Timeline for Is it possible to connect an LED directly to the GPIO of the Pi?
Current License: CC BY-SA 3.0
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| Apr 27, 2016 at 5:43 | comment | added | lvella | From the linked document: "The current value specifies the maximum current under which the pad will still meet the specification. IT IS NOT: The current the pad will deliver. IT IS NOT: a current limit so the pad will not blow up. The pad output is a voltage source." This means that you can't limit the current with programming, and you DO NEED a resistor to limit the current to your LED. | |
| Dec 20, 2012 at 3:26 | comment | added | BobT | 8ma will give you a pretty bright light from a small LED. As far as buffers go, in this case a buffer is a circuit that (for instance) takes a small current drive as an input and sources (or sinks) a much larger current on its output. They are used for driving relatively high current peripherals from low current outputs. An LED is one example, a relay might be another. See evilmadscientist.com/2012/basics-open-collector-outputs for an example of IC buffers. For a discussion of driving LED's with a RasPi see elinux.org/RPi_Tutorial_EGHS:LED_output | |
| Dec 19, 2012 at 6:19 | comment | added | Benjol | OK, thanks for that. So I need to be looking for some more reasonable LEDs. (What's a buffer?) | |
| Dec 18, 2012 at 22:37 | comment | added | BobT | The pin can only source or sink 16ma max, 8ma by default.. You will need a buffer if you truly want to drive the LED with 20ma. If it could supply the current then yes... You only need to drop 1.05 volt, so the dropping resistor should be 52 ohms or so. | |
| Dec 18, 2012 at 12:46 | comment | added | Benjol | Just in case: for 2.25V and 20mA LED, that works out at about 50 ohms, is that right? | |
| Dec 13, 2012 at 18:15 | vote | accept | Jay | ||
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| Dec 13, 2012 at 18:11 | review | First posts | |||
| Dec 13, 2012 at 20:19 | |||||
| Dec 13, 2012 at 18:10 | history | edited | BobT | CC BY-SA 3.0 |
added 170 characters in body
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| Dec 13, 2012 at 17:52 | history | answered | BobT | CC BY-SA 3.0 |