Very nice indeed. Managing 32 PWM levels on a 4*5 matrix completely in software is impressive. And a good refresh rate as well.
Code wise, I like the way you lay it out, especially the comments. I hate the recent trend of putting comments within a procedure and in the code space ( and on every other line). Your full width comments before and right side comments during a procedure (and initialisation) should be mandatory.
I also like the neatness of the end_of_period and end_of_cycle checks. I'm assuming that you couldn't find a way to avoid the asm - the shift at end_of_period looks like it should be C able.
The only thing I can see that isn't required is the clearing of PIE1.
Overall an excellent example. A++.
Mike.
BoostC Charlieplexed PWM 32
- 25th June 2008 12:34 PM #1Mike, K8LH
BoostC Charlieplexed PWM 32
Would anyone care to study or critique my very first BoostC program?
It's a novelty 12F683 program that does 32 PWM brightness levels per LED in a Charlieplexed matrix of 20 LEDs. The refresh rate is 62.5 Hz and each LED duty cycle can be varied from 0% to 20% in thirty two 0.625% (100 usec) steps.
The picture doesn't seem to show the smooth transitions I'm seeing. In fact you can hardly tell those are green LEDs.
Mike
Last edited by Mike, K8LH; 25th June 2008 at 12:44 PM.
- 25th June 2008 01:15 PM #2Pommie
0
- 25th June 2008 01:50 PM #3BeeBop
WOW!!
Yes, I must agree with Mike(Pommie); this is very well done, and your source is so well commented and very easy to follow.
Mike(Mike, K8LH,) I think you should have an award for getting the most punch out of the least resources!!
0
- 25th June 2008 05:24 PM #4edeca
That's really impressive. I was considering doing something similar with the 8x8 square LED blocks from Futurelec to display patterns, I hadn't considered PWM to dim the lights. I might have to try on a much smaller scale with the Junebug LEDs tonight
What's the board you are using, it looks like a nice size for prototyping or small projects.0
- 25th June 2008 05:32 PM #53v0 Moderator
Mike: I like it
0Last edited by 3v0; 25th June 2008 at 05:34 PM.
Please post questions to the forums. PM's are for personal communication.
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- 25th June 2008 07:02 PM #6Mike, K8LH
Gentlemen,
Thank you all for the nice comments.
Pommie,
I'm still trying to come up with optimized C code to replace those remaining few assembler sections. The C code equivalent for those rlf instructions uses two more words and cycles. I guess I'm being a "tightwad" (grin).
edeca,
That's a small Radio Shack proto' board made of phenolic or similar material.
Regards, Mike0
- 25th June 2008 11:55 PM #7futz What is that second "jack" thing - lower left? Is that your programming connector? Better lighting and a second 3/4 angle shot would be good.
Originally Posted by Mike, K8LH 
Cool little doohickey! You should do a YouTube movie so we can see it in action.
0Last edited by futz; 25th June 2008 at 11:58 PM.
- 26th June 2008 12:59 AM #8Mike, K8LH
I use 3.5mm sterio jacks on proto' boards for TTL232 connections.
Sorry about the picture. I tried several different shots, lighting, shutter speeds, etc., trying to show off the smooth fade from about 10% to 100% brightness but never did come up with a good shot. I even tried it with red LEDs (below) but "no joy" as the color is all washed out.
I don't have any video equipment for YouTube. Sorry.
BTW, thanks for turning me onto BoostC. Writing C code for 12F' and 16F' devices for the first time is a blast.
Regards, Mike0
- 26th June 2008 01:10 AM #9mneary
The green LEDs look good on my monitor.
The brighter ones are a little washed out but the effect is perfect.
Photography is a lot better than I would normally do.
0
- 26th June 2008 02:34 AM #10futz You have a digital camera!?!? Never seen one yet that won't do video. That's how I do mine. Originally Posted by Mike, K8LH
Kewl, huh? And C code is very very portable from PIC to PIC. I wrote code for 16F88 and with only minor changes ran it on 18F248.BTW, thanks for turning me onto BoostC. Writing C code for 12F' and 16F' devices for the first time is a blast.0Last edited by futz; 26th June 2008 at 02:35 AM.
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