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How do I use a battery with the Spider RTC?


#1

I have a spider, VC#, up-to-date firmware, etc.

I sett the realtimeclock.
I disconnected the USB cable for a few seconds
After power up, the realtime clock is zero.

I found some references to “described in the ebook” I read the ebook and other materials in the turorials, but found no reference to installing or checking the realtime clock battery.

I did find some references to batteries for other boards.


#2

asking how to connect a battery or how to set time in code?


#3

Does the Spider have a battery?

How do I connect a battery if there is none?


#4

The VBAT pin is connected to Z socket. The schematic is the best way to find it http://www.ghielectronics.com/catalog/product/269


#5

It would be nice to check that off my to do list as well.
Talking about how to add an RTC battery to the spider.
Thanks.


#6

Easily, plug in the extender board then solder a 3V coin battery on there.


#7

Looking at the Spider schematic, I finally found where EMX Pin 28, RTC VBAT goes.

Socket X2, pin 5.

so I can connect the 3.3v battery to socket X2, pin 5


#8

Yep, 3V as there is no 3.3V coin battery.


#9

So to do this, I will connect the + of the battery to pin 2 on z socket and the - to the ground of the socket, Is that correct?


#10

The code examples under “Time Services” led me to believe there may be a battery installed


To use the RTC hardware, we first need to check if the RTC hardware has the valid time or not. Maybe this is a new battery or the new system and the RTC has not been set yet. If RTC has a valid time then we can read the RTC (hardware) and use that to set the NETMF system time (software). If time is not valid, then you will need to set the RTC to the correct time.
 
But how do we check if time is valid? One way is to use the built in battery ram to store some magic numbers that we check later to determine if the battery ram data is still valid. If they are then most likely the RTC is valid. Also, it is a smart idea to check the RTC for some reasonable time. For example, check if the year is not less than 2011.


#11

The code example is not for spider specifically, it is general talk and some systems may have a battery on board.


#12

Yes, on the Spider socket X2, pin 5 is the RTC battery +. The battery - can go to any ground - but, you should use the ground in the Z socket.

Looking at the documents for socket definitions, the Z socket has MS for pins 3 through 9, whatever MS means - it is not defined.


#13

Thanks Tom,
I think it means, manufacture special…


#14

ms == manufacturer-specific


#15

Ah I was close… Thanks Mike


#16

If you plan to use a RTC battery, look at

http://biz.maxell.com/products/industrial/battery/ml/pdf/batteries_ML.pdf

Use a diode and resistor from 3.3v.