I have a MKR Wifi 1010 board. I am trying to figure out the right value of a resistor as a current limiter for a typical 2V red LED that can draw a maximum of 20mA.
I did some testing and without a current limiting resister, it seems the MKR Wifi 1010 will only let 7mA flow. I see a note in the full pinout here at the bottom of each page that the max current per pin is 7mA.
Can I assume correctly that the board has a current limiter for each pin? I think this means I don't need a current limiting resistor since the pin already has that protection well below the 20mA I am worried about.
BTW, a 100ohm resister gets 5mA flowing through the LED and a 220ohm resister gets 3mA. Neither of these are very bright. But the 7mA without the resister is OK for my application.
I also see the pin group maximum current is 65mA per group. Are all digital pins considered a group or is there some other grouping like the ports (PA vs PB? or PAxx through PBxx)? I tried to google this, but I did not find an answer.