Bit Angle Modulation (BAM) in a PIC

[Darrel Taylor]

RadikalQ3,

Thanks for the Mirror Image idea!
It has completely removed the blinking problem.

Unfortunately the higher frequency and extra code to reverse things has created some new ones, but I think I can work through them.

For your first post here, it was an awesome one.

Thanks again,

Also, thanks anonymouse,
But with multiple channels at different dutycycles all using the same timer, changing the interrupt sequence at 127 isn't possible.
I hadn't mentioned the multi-channel part yet ... oops.

[RadikalQ3]

RadikalQ3,
Thanks for the Mirror Image idea!
It has completely removed the blinking problem.

Oh, it's nothing... just was an idea.
I have spent the last days reading all I found in internet about PWM, BAM, Frecuency Modulation, etc.
I have a project to do and I am gathering all the information about this topic.
Simply... I found your topic (and this forum) and I thought that was a nice challenge solve your blinking problem O
I am waiting the recepcion of some hardware and in a few days I can do test with this for my own.

Later, I realized that this is a forum on basic! (and I just use assembler)

[Darrel Taylor]

Videos of oscilloscopes never seem to work very well.
But it's interesting to watch the way the mirror image works.

Let's call it BAM-BAM.

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/4eZho2fN3r8&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/4eZho2fN3r8&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

It's going through a ramp from 0-255 and back down.

[Ioannis]

Hi Darrel. It looks very good! Congratulations on that!

Very good job.

Ioannis

[JEC]

I'd run in to the exact same issues between 127 and 128. Never had time to investigate it further.

My implementation just used a state machine in the interrupt routine - 1 state for each bit.

Each state sets TMR1 to a different level, then sets / clears the appropriate pins.

I assume that you're implementing the 2xF 'mirror' method in a similar way? Very clever.

[Darrel Taylor]

Hi Ioannis

Hi John,
&nbsp; Just yesterday I was thinking about how this might be good for your Christmas Lights.
&nbsp; Apparently, the thought had not escaped you.

I assume that you're implementing the 2xF 'mirror' method in a similar way?

Well, the best method, is still to be determined. I'm trying every way I can think of ...

Currently, I'm rotating the DutyCycle out to the Pin, and when rotating it left, I shift the timer value Right to give 1/2 the period for the next bit, when rotating right, the timerval gets shifted left for 2x the period.

I'm also trying to incorporate the "Cylon Scanner" that Bruce and I were playing with last year.
With the mirror image, the bit's are scanned back and forth much like a Cylon (or Kitt the car).

Never thought that optimization exercise would actually be useful some day.
<br>

[JEC]

&nbsp; Just yesterday I was thinking about how this might be good for your Christmas Lights.
&nbsp; Apparently, the thought had not escaped you.

Pity the 10F doesn't have a TMR1...

[RadikalQ3]

Let's call it BAM-BAM.

Better... BAM-MAB

[Darrel Taylor]

Better... BAM-MAB

I had thought of that ... but it was too hard to say (unless you're drunk).
Besides, I thought maybe Pebbles would show up to see what BamBam was doing.

Progress is cranking.
Should have an update soon.
<br>

[mister_e]

Should be BAMAB... unless your program stick too much on a side of the PWM cycle ;o)

[bcd]

I played with BAM some time ago, but always found this step in the middle of the range to be its big issue. Thank you for a workable solution !!!

Its interesting that Artistic License (the inventor, or populariser of BAM) make no mention of this issue.

Bill.