Author Topic: Need help choosing a robot brain  (Read 1362 times)

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Offline klimsTopic starter

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Need help choosing a robot brain
« on: December 26, 2010, 12:17:27 AM »
Hi guys,

I'm looking at upgrading my robot brain to something able to do some image processing.

Someone with a bit more electronics knowledge than me mentioned that when I'm doing communications with other hardware this is time wasted because I cannot process any other data. If I'm spending 50% of my cycles doing communications then getting a super fast processor won't really be that useful.

My question is does anyone know of a device (micro or mini computer) that has the capability to leave communications up to another device/IC and not effect the main processor? I was reading over the RoBoard harware introduction and it seems to point at something like this.

Can anyone give me some advice on what the hardware is called that I am looking for?


thanks,
Andrew

Offline Soeren

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Re: Need help choosing a robot brain
« Reply #1 on: December 26, 2010, 05:36:33 PM »
Hi,

Plenty of small form factor "PC's" to choose from.
The smallest (currently) is the CoreExpress (58mm×65mm)
http://en.wikipedia.org/wiki/CoreExpress has an overview of all the sizes.

The PC-104 probably have the best support though.


Anyway, using DMA transfers will free up a lot of processor time.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline klimsTopic starter

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Re: Need help choosing a robot brain
« Reply #2 on: December 26, 2010, 07:55:41 PM »
Thanks for the feedback Soeren. Looks promising.

I don't even know if I am really asking the right question about the communications processing taking up CPU time. Does this sound right? Is this a limitation of microcontrollers and not really a problem with PCs? Can the same be said for these small form factor PCs?

I'm sure these questions have been asked before but I don't know what it is exactly that I'm trying to find out about communications and embedded systems. Can anyone help me out?


thanks guys,
Andrew

Offline Soeren

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Re: Need help choosing a robot brain
« Reply #3 on: December 27, 2010, 06:28:40 AM »
Hi,

I don't even know if I am really asking the right question about the communications processing taking up CPU time. Does this sound right? Is this a limitation of microcontrollers and not really a problem with PCs? Can the same be said for these small form factor PCs?

Well. it's all about throughput. If you need a CPU to do several things concurrently it will need the speed to handle it, but using DMA, for the transfer, it just needs to set it up once and let the DMA controller handle the rest, so it's not occupying CPU time - Sort of multitasking.
PC's (of all sizes) use DMA extensively.

If you wanna use an AVR, take a hard look at the XMEGA which has got 4 channels of DMA.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline klimsTopic starter

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Re: Need help choosing a robot brain
« Reply #4 on: December 29, 2010, 09:39:22 PM »
Thanks again for the useful info Soeren.

I was chatting to a friend about using a small x86 computer and he mentioned that the x86 architecture has communications built in to the chip. Specifically I have been looking at the RoBoard with the Vortex86DX. The block diagram suggests that this is true: processing is not directly handled by the CPU and so will not be blocked from processing other information when carrying out communications.

Is my interpretation of these diagrams right?

Offline Soeren

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Re: Need help choosing a robot brain
« Reply #5 on: January 03, 2011, 10:43:17 PM »
Hi,

I was chatting to a friend about using a small x86 computer and he mentioned that the x86 architecture has communications built in to the chip. Specifically I have been looking at the RoBoard with the Vortex86DX. The block diagram suggests that this is true: processing is not directly handled by the CPU and so will not be blocked from processing other information when carrying out communications.

Is my interpretation of these diagrams right?

I'm not sure how well the drawings reflects how it works, but in general, any system using DMA will do the transfers without bothering the CPU (apart from a tiny setup of source and destination addresses and size).
It's a bit of a stretch to say that x86 "architecture" has got in-built comms, as all peripheral functions is usually done by an external chipset - A controller with more or less of the chipset in-built is a special case, extending on the naked x86.
(Sort of like if eg. a particular brand and model of car is available with AC, it doesn't mean that any of that brand/model has got it).

A microcontroller with a hardware UART won't bother its CPU much by comms either.

Apart from that, it seems to have plenty of interfacing lines, so if the RoBoard brings them all out, you won't be missing interfacing capabilities the first couple of days  ;D
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Admin

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Re: Need help choosing a robot brain
« Reply #6 on: January 09, 2011, 10:55:02 AM »
You can reprogram the Blackfin camera, specifically designed for image processing . . .

http://www.surveyor.com/blackfin/

Offline klimsTopic starter

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Re: Need help choosing a robot brain
« Reply #7 on: January 09, 2011, 03:23:47 PM »
(Sort of like if eg. a particular brand and model of car is available with AC, it doesn't mean that any of that brand/model has got it).
Got it. Thanks Soeren

A microcontroller with a hardware UART won't bother its CPU much by comms either.
I didn't know this. I've been trying to calculate how much CPU time I am using doing communications so this is very good to know.

You can reprogram the Blackfin camera, specifically designed for image processing . . .
Very good idea. Thanks for that Admin!  ;D

 


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