Hello guys from the schematic there should be no difference whether you power M5Atom via 5V on the Groove connector or the 5 V pin in the back. Measuring for continuity between Groove and the respective pins in the back also shows they are connected 1:1 and are the same. Running a simple sketch on my M5Atom Matrix, which only connects WiFi and is showing that by changing the LEDs from red to green, I see that working ok with voltages from 2.8 V to 5.2 V. BTW: I am getting the same results with an M5Atom Lite. Thanks Felix