Robot Control - (edited title)

[jabberwocky]

I'm new to this, so forgive me.

My plans for my 'soon-to-be' robot's brains are this.  I plan to port a version of Linux to my Palm Zire 72 and attach it to my robot.

This PDA in turn, once programmed, control both sensors and motors/servos on the robot.

Ok, now i admit that will be a challenge.  The PDA+linux shouldn't be too much an issue, i've found tutorials online for this.  The part i need help with mostly, is the bit inbetween the PDA and the sensors and motors.

Would an I/O board work for this? and if so, has anyone operated both sensors and motors at the same time, through a usb connection?

Sorry if this is confusing, like i say, i'm new! (but always willing to learn)


The Jabberwocky

EDIT: If this whole thing works, it will be sweet as the PDA has Bluetooth, as does my laptop.

[JesseWelling]

it all kind of depends on what I/O is brought out by the palm. Can it Host USB? Does it have Serial? I doubt it has any A2D or GPIO being a consumer device. The best bet is to hunt around the tutorials you've found and see what kind of I/O you can do.

[jabberwocky]

Looking back, i think i totally confused my post.

Does it make more sense for me to ask help for the following?

I want a MCU to control 2 servos and up to 8 sensors.  A computer will be connected to this MCU at all times and will collect data from the sensors and tell the MCU/robot what path to take.  Occasionally, the computer will order the MCU/robot to take a different path.

Where the heck would i start?  Could/can the Computer replace the MCU?  If so, how?

[JesseWelling]

I want a MCU to control 2 servos and up to 8 sensors

Most sny chip can do 2 but the ones I'm familiar with generally top out at about 6 PWM channels but maybe you could go with a cheap serial (or usb to computer) control board like this if you need more: http://www.pololu.com/products/pololu/#servcon

A computer will be connected to this MCU at all times and will collect data from the sensors and tell the MCU/robot what path to take.  Occasionally, the computer will order the MCU/robot to take a different path.

Sounds perfectly reasonable in theory

Where the heck would i start?  Could/can the Computer replace the MCU?  If so, how?

Generally, unless you use a lot of I/O boards like the serial one above, it not a good idea unless it's an extremely mobile Computer, or you have a good wireless set up. You should start with your budget. It's almost always easier to eliminate options once we know a price range... The next thing is to determine what you want to learn. Is it AI? Control Theory? Micro-controllers? Electronics? Mechanics? Then you can use that criteria to help focus your search.

But going back to your first post:

The part i need help with mostly, is the bit inbetween the PDA and the sensors and motors.

I'd say unless you need finite control just go with a serial servo board and then a MCU that measures analog sensors reports it's a2d values on another serial line if the Palm has them. Then do most of your processing on your palm and out put commands to the servos. How fast is your Palm's processor btw?

[jabberwocky]

How fast is your Palm's processor btw?

Thanks for that reply Jesse, the specs for the Palm i have are,

Size & Weight:     4.6 in. x 2.95 in. x 0.67 in. (116 x 75 x 17 mm); 4.8 oz (136 g)
Processor:          312MHz Intel PXA270; Palm OS 5.2.8
Memory:        32MB RAM; (24MB user accessible)
Expansion:        SD/MMC slot
Screen:          320x320 pixel; 65k-color; transflective back-lit
Audio:                  stereo headset jack; rear speaker
Power:             Rechargable LiIon Poly (950 mAh)
Connectivity:        mini-USB cable, SDIO, IrDA, Bluetooth (v1.1)

My initial area of learning will be electronics.  I'm comfortable with construction and mechanics, and i've dabbled in programming but i've never truly jumped into electronics.

[JesseWelling]

Can the Mini-USB do hosting  as is? The PXA270 is able to but that's assuming it's wired correctly.
If it can't that leaves some hacking of the IrDA and Bluetooth, or the USB. The Bluetooth is most likely a serial connection between the PXA270 and a Bluetooth module so you may be able to use that serial line. I believe he PXA270 has 3 serial lines, and one USB from what I've heard, but they might not all be available with out hacking the hardware. It's my guess that the IrDA is also a serial connection but I'm not too sure. Are you going to use the Palm OS or replace with a Linux Kernel? Do you have any links to the howto's you talked about?

If John Hylands is out there he might know a little bit more about this (or his connection Dave might  )

[jabberwocky]

I'm going to try first with the Palm OS, but it may be more restrictive on port control than Linux (In my honest opinion).  So if i can't find the software for Palm OS, then yeah i'll try replacing it with Linux.  The links that i found for my inspirations and advice are;

http://handhelds.org/moin/moin.cgi/PalmZire72HowTo
http://www.handhelds.org/geeklog/index.php
http://www.linuxdevices.com/articles/AT8728350077.html

Fraid i can't say if the USB can do hosting or not, is there anyway to test that you know of?

[JonHylands]

The PXA270 does support USB host. The gumstix I am using (Verdex) is PXA270-based, and it has a mini-USB port that I use to talk to an FT232 USB -> TTL transceiver.

I don't know how the Palm board is wired, so I can't say for sure that it supports or doesn't support USB host.

- Jon

[JesseWelling]

The HowTo looks a tad spotty but It seems doable, and if you aren't worried about bricking the Palm I'd say go for it, but if you are partial to it... I'd go for something else. I still can't say about the I/O you will have available. Have you tried e-mailing the Author or another group that specializes in Linux on the Palm?

If you have a spot of cash to invest in your Hobby you could check out gumstix. It will pretty much get you the same thing but more general and less one-off-ish, meaning that gumstix run on the PXA (I use the PXA255 which is only 200 or 400Mhz, but the PXA270 you can get in 400 or 600Mhz) which would be very similar to your palm but is already set up with Linux and comes with a great SDK to work with if you are familiar with making any kind of software using GNU tools.

Wish I could help more but the road is a bit hard to see without knowing the what I/O you can get at.
Welcome to system engineering.

[jabberwocky]

you could check out gumstix.

i know next to nothing about Gumstix and have only briefly flicked through the Websites.  If this could provide more than my palm 'as-is' then its certainly a viable option that i would be willing to take.  I can't say i'm that partial to my Palm.  I actually haven't used the thing in a year or two so its now living in my "Stuff to make into robots" box.

I'll be sure and do some Googling for Gumstix this morning, but can you point me to any 'gumstix for dummies' sites?

[JonHylands]

There really aren't any sites like that. The gumstix mailing list is the place to go to ask questions. The wiki (http://www.gumstix.org) has a lot of information, but its not really comprehensive.

I use the gumstix on some of my robots, and its great, but I don't do any low-level programming on it. I run Squeak (Smalltalk) on it, and that insulates me pretty well from the GNU level stuff, but still allows access to things like serial ports and sockets.

- Jon

[JesseWelling]

I use gumstix / robostix as well, and like it. The robostix is pretty much just a microcontroller (an Atmega128) for low level I/O and I use it for things like PWM for motors and servos and A2D and GPIO.