Hi there.
Yesterday I got my Stalker and started some tests. I powered the Stalker through the VCC/GND pins of the program port, using a USB/TTL cable. I mounted a backup battery (CR2032) on the board.
Using the DS1307RTC and Time libraries, I set the RTC clock to my laptop’s clock, and everything worked as expected. I set 10 seconds as the sync interval in the Time library.
However, after a few minutes I noticed that the RTC on the Stalker lost a few seconds with respect to my laptop (which is kept in sync with NTP). I haven’t calculated an exact figure, but the Stalker seems to loose several seconds every few minutes.
The software clock provided by Time [ now() ] and the RTC’s one [ RTC.get() ] agree, so the two are in sync. It indeed seems that the RTC chip is loosing time, much much more than the few PPM tolerance per month that the Maxim’s chip advertises.
Is it possible that my board got a defective DS1307, or am I doing something wrong?
Thanks!
Hi again.
I did some more analysis: the RTC on my Stalker has lost 17 minutes in 39 hours. During those 39 hours, it was never powered, except for the backup battery (CR2032).
Any hints on what might be wrong?
Thanks,
Luca
It isn’t just you. My Stalker 328 has lost multiple minutes over three days powered with just the CR2032. I haven’t gone through hoops to determine the rate of error, and I haven’t tested with constant 9vdc supplied to the power pins, but if the error occurs when the board is powered with 9vdc at the JST connector, it’s a serious problem.
WOOOOOOW bad news for me 
Can someone vinculated to Seeeduino confirm this?
Is there any solution?
I had been thinking of buying a Stalker but that lose of time will kill my project for sure!!!
Thanks.
Hi All,
We are sorry for the problem.
The RTC crystal may cause this problem, and you can request a replacement or half price get a new Stalker V2.0.
And please if you do not use the Time keeping battery, connect the shortcut the Battery+ to GND.
all the best
Happy new year.
