MIBAM resolution

[david parish]

Firstly appologies if should have added this to an existing thread. It's my first post and I wasn't sure if this subject warranted a new thread....

I have been reading this forum (lurking in the background) for a couple of years and I just wanted to say that it is probably the most useful resource I have ever found on the internet. Although I had been involved in electronics as a hobby and a job for quite some time I had never been interested in programming 'little black boxes' so to speak. Well talk about a new lease of life! The combination of PICs and PBP has completely transformed my use (and enjoyment) of electronics. Without this forum my learning curve would have been so much steeper, slower and more painful. I didn't find the forum until I had made all of the usual beginner mistakes and now I fnd it to be the most amazing resource.

I would like to say a big thank you to all the contributors who have put so much effort in to helping so many of us do such amazing things with these PICs. Mention must be made in particular to Melanie and Darrel - Instant Interrupts changed my PIC world


I have started using MIBAM which is so much better than my own inefficient efforts at controlling LEDs. My one problem is the resolution. When using high power LEDs (1 watt Luxeons) the transition at the lower duty cycles is very, very noticable. Going from off (0/256) to 1/256 to 2/256 etc is easily seen by the eye.

I have been wondering if this is what some people have reported to be 'flickering' when using MIBAM, not actual flickering when an output is in a steady state but the noticable change in intensity when changing from one duty cycle to another at the very lowest duty cycle steps.

I assume that one way to reduce/remove this effect would be to increase the resolution of MIBAM. I don't know if 16 bits would be required (maybe 10 or 12 bits would suffice) and I realise that the number of interrupts and the overheads would increase (and the frequency would decrease), but this would be well worth it to get seamless fades!

I don't know if it would be possible to squeeze many of the lower bits into one interrupt to save having to use one interrupt per bit?

I only wish I was experienced enough to be able to do this myself - but I'm not there yet, and I may never get there either

I would be very interested in your comments Mr. Taylor!


Best regards,
David.

[Darrel Taylor]

Hi David,

Instant Interrupts changed my PIC world

Sweet! Thanks for letting me know.

And yes, those LED's are a bit tricky. I've got a bank of them here on my bench.
Along with the stepedness on the low end, they tend to reach close to maximum brightness at around 170. Only slowly increasing a small amount from there all the way to 255.

If I limit the current so that it reaches maximum brightness at higher numbers (~230) then the low end is much better, but the steps are still visible.

The next version of MIBAM will have ...

• Higher refresh rates with more outputs. (working)
• Selectable resolution from 8-14 bits (almost working).
• Additional Ports using external parallel latches. (working)
• Additional Ports using external shift registers and MSSP. (not working)
• Adjustable LED Linearization tables. (not working)
• It's compatible with both PM and MPASM. (working)

I currently have no anticipated release date.
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