[TriEmbed] measuring low power (Joulescope)

[Pete Soper]

I've been using a TI XDS110 (about $110) that has an "EnergyTrace"
feature that can run standalone within TI's Eclipse-based Code Composer
Studio. This allows measuring supply current to a target with
programmable voltage. It will supply up to 100mA at 1.8 to 3.6 volts.
The accuracy is +/-2% or +/-500nA at less than 25mA and 5% from 25 to
100mA and I have an "extender" add-on (another couple hundred $) that
stretches the current range up to (from memory) 800mA. The CCS IDE in
this setting is just a huge Java GUI glop for enabling the XDS110 and
slurping roughly 2k samples per second into a .csv file (and yes, it
holds these bad boy sample collections in memory until the run is
complete and this would be a major issue for monitoring for long periods
of time if you don't happen to have 128 gigabytes of RAM in your
computer).  The XDS110 is only about $110 and has been extremely
effective for what I've been doing, but I need something that measures
an arbitrary power source with an arbitrary target.

There's a Kickstarter that's going live on the 19th offering a device
called Joulescope <https://www.joulescope.com/> that is passive: it
measures whatever voltage and current is going to a target. It covers
nine orders of magnitude from -1 to 15 volts and -1 to 3A with  1.5nA
resolution and 250kHz bandwidth. The software and front panel connector
design is open source. For an in depth description of this by the
creator here's an interview <https://www.embedded.fm/episodes/278> on
embedded.fm.

My question is whether another TriEmbed person would like to share one
of these with me. We can get one of the "earlybird" first production
units for $400 so that would be $200 each. If you're interested in this,
please email me direct (pete at soper dot us). I'm outside Apex and a
long hike from everywhere, so this wouldn't be like sharing a lawnmower
with a neighbor, but I'm not in a low power-centric business, so I
wouldn't be in a position to use this thing for weeks or even months at
a time (but I wish I had it today!). The production schedule is early
June. The guy involved seems to have done his homework: there doesn't
appear to be any development at all left  for him to do, just the
production so it appears to be relatively low risk, but of course you
can never tell.  So if you're seriously interested, let me know.

Thanks,
Pete


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