6 years ago
includes holes for the rPi expansion connector and info on how to
program the IO along with.... well, ruler markings. Nice gadget but
they want about $5 for it, plus shipping.
So I looked on eBay and found several similar rulers, but without the
ruler markings. One of them had two different pictures with different
markings on the labels next to the pin numbers. I wrote them asking
which one was right and what the labels mean, "Wiring Pi" on one and
"BCM GPIO" on the other. Not being intimate with the Pi IO, I am
guessing these numbers are the IO port bit numbers. But why the two
different labels in the same listing?
So I wrote and asked, pointing out that these must be two different
boards as the pin numbers are the same on each board. Unless... I see
the labeled numbers are not the same between the two. Would it make
sense that this is one board with different info on the two sides for
different versions? I seem to recall another vendor doing that and
labeling the two sides with the version numbers. The two sets of
numbers on this board do not match that.
It looks like the BCM GPIO numbers match the numbers of the GPIO bits
for rev 2 boards on other units like this. But I can't tell what the
Wiring Pi numbers mean. Here are a few pins on the connector.
P N W B
i a i C
n m r M
e i G
3 SDA 8 2
5 SCL 9 3
7 G7 7 4
Obviously I would learn a bit more about this when I actually used it
for connecting I/O to the rPi. I have only connected through USB so far.
The "rude" part comes in that when I asked the vendor about the two sets
of numbers, the reply was, "You probably don't need this if you have no
idea what it is." No further info.
-- Rick C