coding a LFO

[julienvoirin]

Hi

I would like to code a LFO with different waveforms (sin, square, saw for example) in order to modulate a CC value.

It would be sync to the BPM received by the midi In.

It seems that Audiocommander did something to get the bpm with the clockbox.

Any other idea ?

Cheers

[audiocommander]

Hi julienvoirin,

to get the BMP is a relatively trivial task; if you're working with a master, the current version of the clockBox is already implementing everything. I did some slave-extensions to the code as well.

To generate a square or saw waveform should be no prob: you just have to set up a timer (or use the relevant functions in the clockBox example) and change the form appropriately.

Generating a sinus wave in C - however sounds like trouble to me, because (as you surely know), there are no highLevel mathmatical functions on the PIC. So I guess you have to find some ASM-optimized code for this (MB SID? MB FM?).

Dunno if something helpful can be found in the lib; but I'm no friend of this lib anyway, because it blows up your code dramatically - and I'm not sure if it's as efficient as it should be.

Hope this helps

best,

Michael

[julienvoirin]

thnaks for a so fast reply

slave-extensions

the clockbox must be sync to the BPM. I 'll dig onto your code.

some ASM-optimized code for this (MB SID? MB FM?)

hardcore ! but good idea

can be found in the lib

what is this lib ? sdcc ?

thanks again

[bill]

http://ucapps.de/mios/mios_libsdcc_v2_5_0.zip

[stryd_one]

I would look to two places - MIOS code, and piclist.com

[TK.]

It's better to generate the sine wave table-based

The analog toolbox has some code for this, you can easily create any periodic waveform (just have a look into lfo.c and map.c)

Best Regards, Thorsen.

[audiocommander]

Brilliant!

azz- I ought to think of lookup-tables in my first post...

Cheers,

Michael  :)