Using a mega48 with two voltage sources.
Problem when the mega48 power goes down
second voltage supply still on led's
Toggling data direction bits form input to output using an interrupt and software PWM, maximum of 2 pins sinking current at one time.
I am driving 16 LED's fading one up and the one next to it down in a circle that makes a nice simulated rotating light.
When I disconnect the power from just the chip (it disconnects all three pins VCC, AVCC, AREF) The LED's are still connected to another power source. I get random pins that are toggling and the LED's flicker.
Is there a way to make sure the pins will not sink current when the chip is not powered?
or, do I just use a fet and an extra pin to turn the power to the led's on when the mega48 has power?
Link to flash streaming movie clip: