During usage I noticed it would miss a few seconds every week. As the LPC1756 does not have the clock out pin. It made it very difficult to get the correct RTC frequency. To make it easier to set the time I created a menu to set the time and the RTC calibration values. (I also added a mouse jiggler as I was getting annoyed to unlock my work machine every time)

Settings menu of the authenticator

Time settings screen. Asks for year, month, day, hour, minute and seconds. (Currently it only works if you enter the time of the GMT+0 timezone)

DateTime entry in the settings menu

I also did a rework of the main screen. I added the name of the profile at the top and added a numeric value in the circle to see how many seconds are left until the next token is valid.