I have 20 ldr photoresistors that I will connect to GPIO.
I have also a Hifiberry Dac2Pro connected as a hat.
I have meassured with amperemeter in serie from the 3.3volt output and are getting 0.75 mA. Will my 20 ldr get 20 * 0.75 = 15 mA. Ive read that the max current on RPi 4 is 16mA? https://www.tomshardware.com/reviews/raspberry-pi-gpio-pinout,6122.html
Im not sure how much current the HifiBerry draws.
Should I use an external powersupply for feeding the LDR? Can I in that case use 5.2 voltage as powersupply or does it have to be 3.3?
Do I meassure correct? How can I calculate this so I be on the safe side not destroying the RPi