Time going advance in RTC Module-why and how to solve issue of that

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saj

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Time going advance in RTC Module-why and how to solve issue of that
June 24, 2019 - 11:22pm

What may be the possible cause for RTS1307 Module(Purchased from Market) get fast approximately 1sec in 3hrs.

Let me elaborate what I have done,

My code is in xc8 and internal osc configured in 8mhz at mcu16f887.

Display is 7segments 8inch 6-digit, data being extraxted from RTC1307 (MODULE) with I2C,  techique Multiplexed  and two button is used for time setting in h/w side. All are going correctly, but

Once adjusting time with the actual, it is found that after (apprx) 3-4 hours  1-second of its going forward. Is it the problems of RTC1307 Module or others of my h/w or software.

As per my openion that could be only for the cause of RTC module, if so then how do i get rid of that..

Than u.

 

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Oscillator problem
June 25, 2019 - 11:27am

Hi,

The component that keeps track of time on your RTC module is the crystal oscillator. The drift in time should be because of the crystal being damaged or should have used a high frequency crystal in place. You can either try a new board or use DS3231 which is comparitevly a bit costly but is reliable  

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saj

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hi raj,
June 26, 2019 - 3:34pm

hi raj,

I have tested 2 nos rtc1307, as i said already 1st one is fast in 5sec in a day but 2nd one is also fast about one minute in a day.As per dallas AN i experiment whether the crystal is receiving noise from othrs components in breadboard for that once seting the time in rtc the rtc was disconnected from power source and continue running in backup mode, aftter 1 day found that the above 2nd case.

As per datasheet i have understood that all the rtc have a error and by appying various tehcnique that only can be minimize but not completely ZERO.

But if we think about railway clock which provide exact time, how they control this. Are they control with software (ie, if the error comes 1sec in a day and this 1sec is compesate by software in that day and this will continue by software automatically in every day at particular time) or they setup the error free hardware with the application of varios technique.

My question is how do i get exact time for my display clock.

I have not yet experiment on ds3231, once done i will discuss.. time being i expect possible sollution from you..

tnx raj for you suggestion..

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Use 32.786Khz crystal with very low ppm
June 27, 2019 - 12:16pm

When it comes to RTC module accuracy it all depend son the quality of the crystal used. The reason why your RTC1307 module is drifting a lot might be because of a poor quality crystal used on the board. Try buying a quality crystal from a popular manufacturer and check the datasheet to make sure the crystal frequency values is 32.786kHz and ppm value is less (around 50-100). Also note that the accuracy will differe based on the operating temperature and track capacitance. You can refer the datasheet to check how to place an external capacitor with the crystal to solve this probelm. 

Also you can correct this error through software program, because the error will not be linear. That is your error might increase as days past. I am not sure for which application you are using this module and how much accuracy you are looking for. If it is not very sensitive you can try DS3231. Or if you BOM can go high try using a GPS module. Since GPS modules can get time from satellites (atomic clock) they are very accurate and perfect choice for time critical application