RX Question

[kaideejee]

Hehe I see a bandwagon approaching... one two three hup!

Could you also send me a copy please? Im currently thinking about how Im going to do this and other peoples ideas are always handy. Ill probably make my first version a direction controller rather than a speed controller (i.e. bang bang controls with mixing) but then Ill expand it into speed control too.

-- Kev

[kaideejee]

Oh btw my email address is kevdgill at warm letters dot com. Thats my MSN ID as well if anyone wants to add me.

(Id like to see an email address spider interpret THAT one successfully.)

-- Kev

[big_nipper]

I bet the spiders do have trouble with it. I cant send to it either. Try this instead:

ftp://81.106.67.7/Little%20Axe/Little%20Axe.zipftp://81.106.67.7/Little%20Axe/Little%20Axe.zip

Hope it works.

[kaideejee]

Mark - Warm Letters = Hot Mail...? Sorry maybe a bit obscure.

-- Kev

[kaideejee]

Ive managed to download it from the ftp link and Ill have a peruse at some point. Cheers.

[jim]

That went right over my head too Kev! Anyway, got the file via email, thanks Mark. It look reasonably similar to PIC16F code, Ill have a proper look at it tonight.

[kaideejee]

Hehe maybe I was in just too much of a weirdo mood (even for me) when I wrote that.

-- Kev

[fluppet]

Speaking of embedded controllers (and since I cant think of a better place in the forum to mention this), Ive been browsing through my copy of the May 2004 edition of Doctor Dobbs Journal, and noted that it has a feature on using Game Boy Advances for nefarious purposes (Ive not yet read the article, but they seemed to be using one as an oscilloscope and a spectrum analyser).

As a complete system, they would seem like a cunning plan for a top-level receiver/control unit (assuming I stick some PICs in the way to handle the low-level stuff) - although I dont know to what extent a GBA would hold together in combat, even well padded and with the LCD (possibly) removed. I know my way round ARM processors, and using one in this form seems a reasonable alternative to soldering everything together from scratch.

Anyway, I just thought Id mention it, in case anyone found it interesting. (Im unsure whether its still on sale, but being a US mag its probably running behind in the UK.)

--
Fluppet

[talulah]

Andrew, does the writer of the article use the existing operating system in the GBA, or is the existing software completely thrown away?

I dont suppose the existing operating system is particularly suited to real-time stuff, and the graphics drivers are probably a bit overkill for our requirements!

[fluppet]

Sorry about the delay. Ive now read the article, and its not entirely clear - they use an Xport (which sits in the cartridge slot and adds an FPGA and a promising number of i/o lines), but other than saying they use some gcc libraries to do text its not clear what of the OS they use.

Chatting to a friend whos implemented an infocom interpreter for the GBA, he says what operating system? You can apparently set up interrupt handlers for some things; I dont know whether this means the bottom page of memory is in RAM and you can set the entire interrupt handler from scratch (as you can on Acorn boxes) or whether they go through a dispatch routine, which would add a bit of latency. Doesnt sound like theres context switching to worry about, though; Im not sure whether you can turn the screen off to reduce bandwidth requirements, but Id have thought you could (if it makes a noticable difference).

It would be an interesting thing with which to experiment, and probably less of a faff than getting the two SA1100 samples Ive got soldered onto something useful (theyre uBGA). Even a 15MHz ARM 7TDM variant ought to be plenty to control a robot, given some PIC assistance - although I may be pushing my luck with using 802.11 as a control protocol without some serious buffering.

--
Fluppet