I've been looking into leds that are already on the uno. I've even found the schematic and datasheet for the LEDS.
- I've found out that the leds are 0805 series with around 2V forward drop.
- I've found out they are coonected with 5V trough 1k resitor and to TX line for example.
- In the datasheet for LED i've also seen the current they recommend is 20mA
So now this data together it does not go together. And here is my question. What am I missing?
Because If i try to design this myself I see 5V-2V=3V, so the resistor should be such that would allow 20mA with those 3V, so R=3V/20mA=150Ohm.
So I am pretty sure I calculated 150ohms correctly, and i am also pretty sure i checked all the data correct, and yet we are having 1000 ohms on arduino.
Can anyone tell me why? Did I miss something?
Thank you for all your help.