Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Will 5 sec a day delay in DS1307 RTC affect the time accuracy?

Status
Not open for further replies.

swami.gangatharan

Junior Member level 3
Joined
Feb 15, 2012
Messages
29
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Location
CHENNAI, INDIA
Activity points
1,442
i have 5 sec delay per day in ds1307. it will affect the time accuracy. why??..
thanks in advance.....
 

i have 5 sec delay per day in ds1307. it will affect the time accuracy. why??..
thanks in advance.....

That doesn't make sense.
You know exactly the drift of your clock so you can calculate exactly the error in any given period and you are asking us if it is within specification of your application?
 

Hello!

As above mentioned, I don't know the application, but just in case:

An RTC clock is a simple bunch of counters running by itself. Its speed is completely determined by
the crystal (that can be internal in some cases) and can be slightly tuned with the crystal load capacitors.
When requested, you can set the time or read it, but you cannot even stop the clock unless you put some
external hardware to disable the clock. That said, I don't know ALL clock chips, so maybe there are some
with a kind of chip select allowing to stop the clock. But usually an RTC chip is meant to keep the time
running ... all the time...

Dora.
 
but you cannot even stop the clock unless you put some
external hardware to disable the clock.

DS1307 can be stopped by writing a ram value

Bit 7 of Register 0 is the clock halt (CH) bit. When this bit is set to 1, the oscillator is disabled. When cleared to 0, the oscillator is enabled

Alex
 

I think it makes a change in the time accuracy. In electronic goods even seconds matter!
 

I am using DS1307 for RTC. But every day it will be get 5seconds delay compare to other clock..what is the reason behind this??
 

The external oscillator circuitry, read post #4
 

I am using DS1307 for RTC. But every day it will be get 5seconds delay compare to other clock..what is the reason behind this??

Maybe you should try different crystal.
Read data sheet on the clock accuracy, it mantions crystal requirements and tips ..
 

If the your circuit is always on everyday, you can increase or decrease the clock of rtc as much as the deviation.

From your problem, please do this calibration process e.g. at 0:00:06 AM. If you do the calibration when it's at 0:00:00 AM, then the clock 11:59:55 PM and when it becomes 00:00:00 AM, the clock will be calibrated once again, continuously.

Use a RTC ram memory to note that the calibration has or has not done today. and each clock reaches 0:00:00 AM, this value should be cleared. After the calibration process at 0:00:06 AM, set this value, so that when 5 seconds later (when the clock is 0:00:06) calibration process will not be done. (check this memory before do the calibration process)

But if your circuit is not always on everyday, then you need to perform addition or subtraction method based on date of the last calibration. eg date of last calibration is 09/01 and then the clock is turned off for 2 days. then at the 09/03, time should be subtracted as much as 10 seconds (2 days x 5 second/days). and then save last calibration date (09/03) at the RTC RAM. for this method, calibration may not be performed starting from 11:00:00 PM to 1:00:00 AM to prevent possible as the previous method.

The better way, replace it with TCXO RTC (DS3231 or DS3232) :)

Arch Zone
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top