Debugging signals with UBB and headers

Werner Almesberger werner at
Mon Apr 25 21:48:58 EDT 2011

For debugging signals generated by the Ben (on the 8:10 card slot),
one often has to use an oscilloscope. Here is a way for getting
convenient access to the signals, without having to build an entire
circuit and without mistreating cables:

The contacts on UBB are spaced 50 mil (1.27 mm) apart, which is
just half the pin spacing of the ubiquitous 100 mil headers. So we
can solder a header directly like this:

This one gives access to the CLK, CMD, and two data lines. Ground
can be accessed by attaching the probe's ground clip to the side of
the board (the whole bottom is ground):

An improved arrangement for the ground connection would be to
solder a wire to the bottom such that it protrudes on one or two

With two angled headers, we can even access all the signals:

Plus, it's easier to attach the probe to a vertical pin than to a
horizontal pin:

- Werner

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