Knowledge Base

Decrements the SS register.

The behaviour depends on whether the last RTCRead was a time/event read or the date. If it was a time or event, the register is unchanged (seconds cannot be altered). If the last read was the date, it decrements to 1, then rolls under to the last valid day of the current month and (leap) year.

It is possible to create an invalid month/day combination by setting the day of month to 31 then setting the month to say 2. This will be corrected to a valid day of month when an RTCWriteDate is executed.

RTC documentation and tutorial

Dialect exclusions: Not available in dialects before 16.