Toying with the software « Jee Labs Talk

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Toying with the software

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kpegan

I have had my Jeenodes for a while now and just started playing around with them recently. After an experiment in creating a remote air rocket launcher using two jeenodes (more details to come). I started playing with the software and particularly the RF12 library.
After dissecting it for a while I ended up writing my own Arduino library which is similar to but fairly different from the RF12. The library is set up in a class structure and closely mirrors Arduino's Serial class. I also ended up coming up with a different header structure, using just length, sender, and destination, to identify packets. All acknowledgment is handled by the end user.
Thought I would post it here in case anybody was interested. You can download it from github here: http://github.com/kpegan/Radio
Its not quite as complete as RF12 for sure, but for basic communications it is pretty simple, attempted it mostly to learn how the Radio was working.
Best, Kelly

Posted 04/05/2010 17:59:55
tankslappa

Hi Kelly, That sounds interesting, my current project is currently hampered by speed overheads in the RF12 library, so any alternatives are very gratefully received. I will have a look at your site and see if your class helps me out. Steve

Posted 04/05/2010 23:57:52
jcw

Just had a look - nice code! This looks like it will be much clearer for others to understand.
@ tankslappa - What are the speed overheads you refer to? Isn't the main issue for flash use the end-to-end transmission time? I'd expect that min packet size and max baudrate are the main points where you can optimize? The library is just waiting for the hardware, or am I missing something?

Posted 05/05/2010 10:35:45
kpegan

Not sure my code would be any faster than Jean-Claude's. Both libraries as currently configured save data as it arrives and then wait for data to be read in the main loop. If you wanted a particular message to be reacted to immediately on reception, writing an interrupt that reacts as soon as data arrives would seem to be the way to go. Hope that helps.

Posted 05/05/2010 13:56:37
tankslappa

@JC I'm not saying there is anything wrong with the RF12 library, far from it, it's a wonderfully flexible library. It's just that right now I'm trying to shave off microseconds wherever I can, and a flexible library is, by definition, slower than a specifically written, single purpose library.
My port access is now all direct, and even that has hard coded bit masks, I didn't even want the overhead of the few bit rotates in the BITCLR/BITTST and BITSET #define functions.
Sure it's not very portable, but right now that comes second to making it work! BTW, I was amazed how slow the Arduino port access was. Before I switch to PORTD/PIND access I couldn't get the flash to sync above 1/60th, just changing those I got it to 1/160th. Next stop 1/200th, then 1/250th, at which point I stop because that's as fast as my camera will sync :-)
@kpegan, I don't know if interrupts will make it any faster for me, all my RX unit does is loop round going "is there a message? is there a message? is there a message? is there a message?" :-)

Posted 06/05/2010 03:46:41
jcw

> I was amazed how slow the Arduino port access was.
Yup...

Posted 06/05/2010 09:32:13