The module and Arduino are using the SPI mode so the corresponding to SPI communication interface connected SCK MISO MOSI CS and the module using 3.3V battery. Then take a good line burned into the routines code open the serial port observational data you will find the start timing and then power off and then on Arduino electric and time is not reset there is no loss will continue and then timing. DS3234 also incorporates 256 bytes on battery backed up SRAM. When the main power failure by connecting to the VBAT pin power supply are maintained on contents of the memory. The RTC can counting seconds minutes hours day date month and year information. For the less than 31 days of month can automatically adjust the date at the end of the month same time with a leap year correction. The clock operates in either 24 hours or 12 hours format with / AM / PM indication. For each day two programmable alarms and a programmable timing way output. SPI serial data transmission via bidirectional bus. - In the 0 ° C to + 40 ° C range accuracy of ± 2ppm - In the -40 ° C to + 85 ° C range accuracy of ± 3.5ppm - for provide battery backup uninterruptible timing input - Operating Temperature Range: Industrial: -40 ° C to + 85 ° C; commercial grade: 0 ° C to + 70 ° C - Provide two regular alarm clock every day - Programmable Output - 4MHz SPI interface support for modes 1 and 3 -· Digital temperature sensor output: Accuracy of ± 3 ° C - With aging correction register - RST Input / Output