What does the “n” mean for pins like “nRST”?

The n in pins names like nRST means not.

  • A pin named without n, for example RST or RESET, will perform its function (e.g. reset the device) when it is connected to VCC
  • A pin named with n, for example nRST or nRESET, will perform its function (e.g. reset the device) when it is connected to GND

nRESET has exactly the same meaning as overlining the name. For example \overline{\text{RESET}}. Some manufacturers prefer to use n instead of \overline{\text{RESET}} or ~RESET