Here is a test I did last month with no resistors.
Running a simple loop at 100 Hz, for steady light. GPIO set to 2 mA. According to Figure 171 in the RP2040 DS, current should never exceed about 30 mA, less with the LED in series. An LED will need at least 1V to light up, search for LED V-I curves, so if the LED needs 1.5V, the GPIO will be supplying 18 mA or so.
Green at 1/10 (or 10%) duty cycle is still too bright. Yellow and blue are at 3/10 while red is at 2/10. Depending on the brightness you want, the settings will need to be adjusted. There is only one GPIO powered at any time in the picture; luckily my camera did okay with the 100 Hz LED light.
[Edit] These are clear 5mm LEDs. I think wiring in a resistor is good practice. But one might still want to add something like PWM dimming for effects, etc.
Green at 1/10 (or 10%) duty cycle is still too bright. Yellow and blue are at 3/10 while red is at 2/10. Depending on the brightness you want, the settings will need to be adjusted. There is only one GPIO powered at any time in the picture; luckily my camera did okay with the 100 Hz LED light.
[Edit] These are clear 5mm LEDs. I think wiring in a resistor is good practice. But one might still want to add something like PWM dimming for effects, etc.
Statistics: Posted by katak255 — Fri Dec 20, 2024 2:53 pm