rpi.rtc

Simple Python module to deal with DS1302 RTC on Raspberry Pi

Wire map (default conf.)

Chip	Rpi pin
VCC	3.3v pin
GND	GND pin
CLK	pin 11
DATA	pin 13
CE (RST)	pin 15

Setup

sudo apt-get -y install python3-rpi.gpio
sudo python3 setup.py install

Read RTC chip date and time

ds1302_get_utc

RPi date and time (UTC) to RTC chip

ds1302_set_utc

Update Rpi system time from RTC chip

Typically call at RPi startup

sudo date -s `./ds1302_get_utc`

One line to check RTC chip time vs system time

Since RTC store only second and not millisecond a 1s delta can occur (or more after a few days)

# drift in second
echo $(($(date -u -d`ds1302_get_utc` +%s) - $(date -u +%s)))
# human readable
echo "RTC `ds1302_get_utc`"; echo "SYS `date --utc +%FT%TZ`";