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td
Joined: 16 Apr 2015
Posts: 21
Location: India
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| battery connection for inbuilt rtc PIC microcontroller |
 Posted: Wed Apr 22, 2015 3:02 am |
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hi,
In our project we are using PIC controller with inbuilt rtc. I have connected 32khz crystal. But I don’t know where to connect external battery for rtc backup. Can anyone help me to find out the pin of microcontroller for rtc battery? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19537
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| Posted: Wed Apr 22, 2015 3:23 am |
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There isn't one.
To run the PIC's RTC, you have to power the PIC.
What you can do, is put the PIC itself to sleep (selecting the right options to keep the RTC running), and then the PIC will stop running, and the RTC stay alive, and power consumption plummets.
If your main supply is not itself battery backed, then you'll need to add the circuitry to maintain the supply just to the PIC from the battery. |
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td
Joined: 16 Apr 2015
Posts: 21
Location: India
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| Posted: Wed Apr 22, 2015 3:36 am |
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thank you....
that means PIC should be on continuously for that. so it is better to use external rtc with battery. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19537
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| Posted: Wed Apr 22, 2015 3:47 am |
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It's simpler, yes.
However a sleeping PIC, running just the RTC, typically draws perhaps 2uA. |
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td
Joined: 16 Apr 2015
Posts: 21
Location: India
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| Posted: Wed Apr 22, 2015 3:51 am |
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okay.
thank you very much |
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