# RTC — Real Time Clock¶

class rtc.RTC

This class represents the onboard Real Time Clock. It is a singleton and will always return the same instance.

datetime

The current date and time of the RTC as a time.struct_time.

This must be set to the current date and time whenever the board loses power:

import rtc
import time

r = rtc.RTC()
r.datetime = rtctime.struct_time((2019, 5, 29, 15, 14, 15, 0, -1, -1))


Once set, the RTC will automatically update this value as time passes. You can read this property to get a snapshot of the current time:

current_time = r.datetime
print(current_time)
# struct_time(tm_year=2019, tm_month=5, ...)

calibration

The RTC calibration value as an int.

A positive value speeds up the clock and a negative value slows it down. Range and value is hardware specific, but one step is often approximately 1 ppm.