On 12/2/16 8:51 AM, Attila Kinali wrote:
On Fri, 2 Dec 2016 08:05:17 -0800
jimlux <[email protected]> wrote:
I'm measuring 0.350A with max cpu usage on all cores and the following
settings:
@ 5V, right, so 1.75W going full out. That's a useful number to know.
I once did an board with an i.m233 (arm9 at 400MHz) and it did less
than 0.5W IIRC. But I think this is about the lower you can do without
tweaking the OS.
Apart from that I read somewhere that the beaglebones have terrible EM
characteristics. But I can't find my source so take it with a grain of
salt :-)
Yes. The BBB is badly designed in this regard... The RPI is better there.
I must say, there are more of these things available in almost too wide
a variety.. You could spend days going through all the datasheets and
websites - I suspect that they ALL have about the same power consumption
for a given amount of processing horsepower - same feature size on the
die, after all - so it's more about peripherals and ease of use
There are way too many, IMHO. And a lot of them are not usefull for
a lot of stuff or have very bad support. The Odroid are a prime example
of this. There is a "community" around them, yet getting them to do
anything usefull is a major pain. There is a handfull of companies
I know of, who do provide good support and those are the ones I am
usually sticking to (unless I have special needs).
And, it's more likely that idiosyncracies in the distros have been
identified and it's more likely that the software will run on them after
its built.
It's actually better to go with a company who is invested in giving
you a working board than using something popular. Especially one that
cares to push all its patches upstream.
Beside the mentioned Toradex, and Aries Embedded, there is also Olimex
which is known for it's wide variety of boards with good support.
Depending on your exact requirements, I would probably go for one of
the i.mx233 boards (the imx233 nano is quite neat) or A10 or A33 board.
Especially the i.mx233 is nice as it has an on-chip Li-poly charger/controller.
All you need to do is to supply it with 5V and it does the rest.
A note of warning: a lot of the boards from Olimex have not enough ground
pins for the high speed singals they provide. If you are transfering data
with high-speed (several 10MHz) over the headerpin connectors, you will need
to add some additional ground connections.
What are the exact requirements you have? How much computational power
do you need? How do you interface the sensors? How many boards will
you need? Is it out of question to build your own processor board using
one of the ARM9's in QFP? What is your budget?
We're processing several thousand samples, received over a serial port
or USB in a few seconds. The algorithm (in Matlab, hence the need for
Linux) grinds for around 30 seconds to produce the output.
we're not sensitive on the "board cost" - labor to design a board is
expensive, so a board that has low power, and the right connectors, so
it's <1 day to make cables, etc. is a better deal than several weeks to
design a board and spin it, etc.
The reason why I'm asking the last two questions is, it is often more efficient
to do your own CPU board if you have to design a PCB anyways for the sensors,
need more than 10-20 boards and you can live with one of the "small" ARM9's
that come in QFP packages (like the i.mx233 or AM1705).
That would come later, and be "someone else's problem" - We do the proof
of concept, "demonstrate that it works in a relevant environment", and
then it goes from there.
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