I have two identical ATMega328P-PU chips. Both sleep unless wakened on digital pin 3 (INT 1). One chip has power, the other one does not. The chip with power can send a signal when awake via digital pin 9 (PCINT1) to the digital pin 3 (INT 1) of the second (un powered chip) to wake it.
Everything works great. No problems.
When I put an ammeter on the power to the chip with power I see ~ 35mA wake, ~12mA sleep. If I disconnect either the pin 3 - to pin 9 or the serial RX - to - TX wires my readings are
~0.1mA sleep and ~ 22mA wake. Please keep in mind digital pin 9 is HIGH only when the powered chip is awake. When it sleeps all pins (that are output) are low.
I am a beginner so please bear with me if this question is basic.
It appears to me even though the second (un powered) chip is not on. some how it can draw amperage from another chip even if the wires connecting are LOW.
My goal is power savings so obviously a 22mA cost vs. 0.1mA is an issue for me.
Any and all suggestions would be great.
Thank you all in advance.