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I see a lot of conflicting documentation on how many GND pins are available on model B rev. 2.0. I have hardware revision "000e" and there are a lot of DNC (Do Not Connect) pins.

http://pi4j.com/pins/model-b-rev2.html says there is 1. http://raspberrypi.znix.com/hipidocs/topic_gpiopins.htm says there are 5.

Which one to trust?

Ideally I want more than one ground pin as I currently have a problem when I detect digital pulses almost simultaneously on multiple pins (I have connected four electrical meters which gives out one pulse per Watt used) - it seems there can be interference, meaning I am detecting ghost pulses. So I want to split my electrical meters in to each seperate GND instead of the common one on pin 6.

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The first 26 pins are the same as on the A+/B+.

           pin  pin
3V3         1    2         5V
0/2 (SDA)   3    4         5V
1/3 (SCL)   5    6         0V
4           7    8         14 (TXD)
0V          9   10         15 (RXD)
17 (ce1)   11   12         18 (ce0)
21/27      13   14         0V
22         15   16         23
3V3        17   18         24
10 (MOSI)  19   20         0V
9 (MISO)   21   22         25
11 (SCLK)  23   24         8 (CE0)
0V         25   26         7 (CE1)
           .......
0 (ID_SD)  27   28         1 (ID_SC)
5          29   30         0V
6          31   32         12
13         33   34         0V
19 (miso)  35   36         16 (ce2)
26         37   38         20 (mosi)
0V         39   40         21 (sclk)

So there are grounds available on pins 6, 9, 14, 20, 25.

| improve this answer | |
  • Not to be scrupulous but do you have any official documentation on this? I have not been able to find any. – DHS Dec 13 '14 at 13:37
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    @DHS There are certainly multiple versions of this around and none of them conflict, AFAICT, except in so far as the one diagram you've linked labels four of the grounds "DNC" (do not connect? why not? one of the 5V is labelled that way too -- I would guess this has to do with the Pi4J lib). Interestingly, their link about the P1 header (under "Additional Resources") has the correct layout. – goldilocks Dec 13 '14 at 13:54

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