I´m trying to understand all components on the NANO 33 BLE board. Most of them are quite obvious, but some I dont quite understand. I hope you can help me.
Looking at the top right sections of the schematic, where the RESET button sits is a component marked J3. I assume those are the 5 dots on the bottom of the board. Can I understand that as some form of ICSP port? If so it doesnt seem to follow standard pinout for an ICSP port as described here: https://www.arduino.cc/en/Tutorial/ArduinoISP
A bit lower are 2 components marked U4A and U4B, that I can´t associate at all. There is a comment next to it saying Crypto Auth. Does someone know what kind of components those are and what their function is?
Thanks for your help! Andre