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VBAT on FEZ Panda


#1

Hi,
I would like to keep the real time clock running after power failure on the FEZ Panda, and noticed that in the schematic the VBAT (pin 19) is tied to VCC in the circuit. In the FEZ Domino this pin is exposed (pic attached). Has anyone tried to modify the FEZ Panda to have a VBAT? Or am I missing something?

http://www.microframeworkprojects.com/images/5/51/FEZ-Panda-Schematic.png

Thanks,
Greg


#2

Here is the FEZ Panda schematic. Seems if I locate the trace, and cut it, should be able to put a Shottky diode in place to block the battery from running the rest of the system during a power outage. Am I off base here?


#3

you’ve missed the very important point; Panda does not have a RTC. The lower-pricepoint chip USBizi100 doesn’t have one, whereas the USBizi144 that is in the Domino does.


#4

Even if you put battery on that pin you will not get RTC, you also need 32Khz crystal


#5

ok, so if “hacking” one was an option (and for me it is) the Panda is capable, it’s just not connected? Cool. Tonights project :slight_smile:


#6

Oh yes it is and I would love to see a picture of your hack :slight_smile:

Have you seen this? http://www.microframeworkprojects.com/index.php?title=SD_Card_Connection_Guide


#7

Yep, seen that, and if I do this I’ll model a show-and-tell on similar grounds, especially including my most recent “everything” daughterboard (i2c eeprom, RS232, and SD card). Unfortunately I have a green fez Panda from the pre-release sample batch so I won’t be doing a white board hack - well not for now :slight_smile: If this one pans out, maybe :slight_smile: I had been delaying any kind of soldering on that small pitch pins, but i did do some SMT soldering the other week for the first time (on this green Panda) so I guess an RTC is a worthy first-go !


#8

Gus, is there any reason why the RTC pins wasn’t just brought out to small pads? Soldering to those pins will be more “fun” then i’m up for… :slight_smile:

Thanks,
Errol


#9

I knew this would be a hack, AND I knew it was possible in looking at the datasheet for the LPC2387. I was just wondering if anyone has done this before. However, I’m now glad nobody has ruined the fun for me. ;D

Luckily I have a good microscope and tiny tip soldering iron…

Thanks all…