

Rex – palm-sized, single-board computer for DIY robots - pnr
http://www.kickstarter.com/projects/alphalem/rex-the-brain-for-robots

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C--
Just asking to those with more knowledge than me. How is this any different to
a RaspberryPi or a Beagle Bone Black?

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bad_alloc
The RaspberryPi is supposed to be a computer you can use like a regular one.
Rex seems to have a dual role: It's designed to control a robot (lots of pins
and extension boards) and to act as a general purpose computer. So it sits
somewhere between an Arduino and a RasPi.

~~~
georgemcbay
The BeagleBone Black also sits in that range in that it is both an ARM-based
general purpose computer but also has 2 real-time programmable
microcontrollers onboard. Which isn't to say that this Rex project has no
value, if it is produced it would be a much easier out-of-the-box experience
for someone to just plug in some garden variety I2C motors and get going than
it would be on the Black, but this sort of combined computer/microcontroller
design isn't unique to it.

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georgeecollins
As someone who makes a lot of robots, I will support this on principle. I
really like that the board can accept a high current power source and has a
cutoff switch.

I am always a little nervous about building a robot around a board when I am
uncertain about how it will be supported. If you are really building robots
that are going to be used out doors or in rugged environments you want to be
able to replace every part. Controller boards aren't really the expensive part
of robots.

For Decapitron, an autonomous combat robot
([http://forums.parallax.com/showthread.php/140197-Decapitron!](http://forums.parallax.com/showthread.php/140197-Decapitron!)),
I have had to replace the controller board twice. That may sound like a lot
but shorts and power surges aren't that strange in combat. But now that board
isn't made anymore. So it is a big problem if the board gets damaged in
combat. That's the advantage of using something really standard, like Arduino
or Raspberry Pi. I can get one of those next year.

Still, I will try this.

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protonfish
As a hobbyist AI programmer with few hardware skills my dream is a for an out-
of-the box robot with basic movement, sensors and maybe an arm that I can
start programming for in a higher-level language. Rex looks like a huge step
in that direction. If they could throw in a chassis for mounting standard
motors and sensors, even my multi-thumbed self might be able to make it do
something cool.

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veemjeem
You might want to check out ROS from the willow garage people. It's probably
the right tool that you're looking for.

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fosap
I wonder how much power it drains. The RaspPi uses "only" 3 Watt, but that is
a way too much for many interesting applications. There are some hacks to
reduce to the power usage (by replacing the voltage regulators for example)
but i wonder how much this board will use.

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Florin_Andrei
Well, in most cases when 3 W is too much, the application is simple enough
that you could do it with an Arduino - which draws far less power.

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ianbicking
I always wonder with these boards why wifi isn't just built-in. It seems like
a delightfully simpler interface than any wire, and means the base system can
integrate with anything else over the network. Sure you can always add wifi,
but the point of these boards is that they bundle all the basic stuff, and
often include things like development environments that can't make use of wifi
if they don't know if it is available. Power is a concern, but you can still
turn it off.

~~~
jerryr
It's probably omitted to keep the base cost down. WiFi modules that you can
get for low-quantity applications are expensive[1]. Cheaper modules generally
require higher-volume consumer electronics applications--not to mention
volumes of NDAs simply to get module documentation. Adding WiFi (or wireless
comms of any type) also makes you an intentional radiator[2], which
potentially complicates your FCC testing, adding cost and delay. So, from an
MVP perspective, it makes sense to leave WiFi off if it's not critical to the
base application--at least for your first revision.

[1] TI's budgetary pricing for one such module--the CC3000--is about $10:
[http://www.ti.com/product/cc3000](http://www.ti.com/product/cc3000)

[2] [http://en.wikipedia.org/wiki/Title_47_CFR_Part_15#C_-
_Intent...](http://en.wikipedia.org/wiki/Title_47_CFR_Part_15#C_-
_Intentional_radiators)

~~~
ianbicking
Thanks for those details, it makes more sense. People usually talk about the
cost, which I don't buy – it's worth $10/unit, and these aren't super-low-cost
units anyway. And in this case consumers of the Rex aren't going to develop
something that will be the basis of thousands of units where that $10/unit
cost becomes a big deal.

But I can definitely see how the regulatory overhead would be a big deal, and
it seems like that regulation also makes other aspects of integration more
bureaucratic. Like I bet a bunch of these chips could be used inappropriately
(e.g., to emit stronger signals than are allowed) and they are using NDAs and
such as an alternative to other security measures. In a sense USB wireless
standards are the one interface/security layer that is well enough spec'd that
it is easy to integrate.

~~~
jerryr
Yeah, I can see how the cost argument is borderline--it really depends upon
what you value & connectivity is pretty important nowadays. But, unless the
primary application is specifically "connected robots", I do think it makes
sense to omit it for the first rev and get a cheaper product out faster. Don't
forget that the $10 is the cost of the part itself.* You still need some
support circuitry, hardware development time, software development time,
testing time, etc. And then there's markup. Assuming absolute minimal costs
for all of those--and direct sales with an aggressively minimal margin, I'd
still expect a $10 part cost to translate to at least a $20 product cost.

* Admittedly, that $10 is _budgetary_ pricing and would probably come down with negotiation (and there might be cheaper low-volume options--that's just one I knew of offhand). But that's likely still the order of magnitude for the quantities of the Rex.

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stinos
Couple of things I wonder:

\- SdCard + full-blown OS = SdCard dies after a while? Or more serious
problems like the rPi simply yielding it empty? Could another type of storage
be used to boot and run from?

\- more information on the OS? What's it based on? Open source so we can
fiddle with it?

\- what processor is that exactly? Likely the manufacturer provides an OS +
libs for it as well (like Ti does for their OMAP), probably the board can be
booted with that as well?

\- will the schematics be open-sourced?

\- debugging capabilities of running programs?

btw quite some comments starting with "I wonder" here. Authors should provide
more information probably..

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crunchex
Howdy, project creator here.

The OS is based on the Yocto Project, so it's a distro we're putting together
ourselves. It's still under heavy development, but the goal is to have
something minimal that we can throw all our support under without having to
rely as much on other distros that already have tons of other boards/projects
to worry about.

We haven't committed to open-sourcing the hardware yet, but all the software
will be FOSS. The stuff we have so far is on github, and feedback would be
great.

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fencepost
Am I the only one to see this and think "They're going back to PCMCIA?" (see
[http://en.wikipedia.org/wiki/REX_6000](http://en.wikipedia.org/wiki/REX_6000)
for a "palm-sized single-board computer" complete with 240x120 monochrome
touchscreen).

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smilekzs
[http://alphalem.com/pages/alphalem-os](http://alphalem.com/pages/alphalem-os)

I like the reference to
[MCP]([http://tron.wikia.com/wiki/MCP](http://tron.wikia.com/wiki/MCP))!

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Octplane
Am I the only one to see $90.00 pledged of $90,000 goal with only 5 backers ?

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Kliment
Yes, looks like this just started today, so it's reasonable.

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joshu
Stuff like this is why I run BigBoardList.

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jboesch
Very cool!

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khamoud
Awesome!

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JakobStorm
Nice!

