Did anybody hear about "NCO" with PIC 16F1507

[albpower2seq4sid]

Hello! This es what I found in the PIC16F1507 Datasheet

• Numerically Controlled Oscillator (NCO):

- 20-bit Accumulator

- 16-bit Increment

- Linear frequency control

- High-speed clock input

- Selectable Output modes

- Fixed Duty Cycle (FDC) mode

- Pulse Frequency (PF) mode

• Complementary Waveform Generator (CWG):

- 6 selectable signal sources

- Selectable falling and rising edge dead-band

control

- Polarity control

- 2 auto-shutdown sources

- Multiple input sources: PWM, CLC, NCO

Does anybody see the possibility of any interesting module to be build with this PIC? may be an VCO controlled via MIDI or something else?

[jojjelito]

Hmm, this could make a fine NCO/DCO using direct digital frequency control. So, MIDI control would be possible. However, this looks like it's intended for high resolution motor control. It's possible that it can also go lower in frequency in the audio band. Note that it only outputs square and pulse-waves so you need a waveshaper in order to get any other waveform. The CWG is for more servo or stepper control trickery.

But, add a CEM3396 or a similar waveshaper and you're good to go. This is what DSI (Dave Smith) is doing with the DSPic and the PA397 (later derivative of the CEM3396) in the Prophet-08, Mopho etc.

[albpower2seq4sid]

Ok, I saw cem3396 datasheet and it also looks good for almost a complete synthesizer, It features 4 VCA, 1 four pole VCF, it is really interesting, so I look other way to add a VCO, like the CEM3340, or a dual VCO, CEM3374; but they are very expensive at ebay. In this case ( Using VCO's ) I would have to control them via the AOUT_NG Module ( and therefore via MIDI with MBSEQ ), although such module presents half tracking in their bipolar configuration, ( 1/2 Volt / Oct ).

Perhaps using a very cheaper CD4046, a PLL with an internal VCO to generate pulse signals to drive the CEM3396 could be enough, I think the CD4046 was used inside the PolyMoog, wasn't it? but in order to drive a MO83 and MM5823, Octave dividers

Hmm, this could make a fine NCO/DCO using direct digital frequency control. So, MIDI control would be possible. However, this looks like it's intended for high resolution motor control. It's possible that it can also go lower in frequency in the audio band. Note that it only outputs square and pulse-waves so you need a waveshaper in order to get any other waveform. The CWG is for more servo or stepper control trickery.

But, add a CEM3396 or a similar waveshaper and you're good to go. This is what DSI (Dave Smith) is doing with the DSPic and the PA397 (later derivative of the CEM3396) in the Prophet-08, Mopho etc.

Edited October 22, 2011 by albpower2seq4sid

[jojjelito]

Well, the slight issue with the 4046 is that you need it to be under exponential control to be musically useful. Take a gander at the fine work of Thomas Henry who coaxes 7 octaves out of some PLL chips. Watch your brand! Matthias Herrman (Fonik) made some very nice looking PCBs a short while ago. The thing is that those make a complete VCO with it's own waveshapers. It has the nastiest sync sound I've yet to hear!

You then need to send the square-waves (and nothing else!) through the 3396 waveshapers if you want to use that IC fully. Otherwise you'll end up with a glorified VCF/VCA combo better buiit using other means.

You'd be better off if you could get direct control over the generation of square-waves for the timing of the 3396 VCO/Waveshaper. It's easy to set up a V/Oct VCO in your lab, but very much overkill for cost reasons. That's why lots of polys used timer chips under control of 8-bit micros plus several 3396's for the synth voices. It would be very expensive to use discrete VCOs, even VCO chips as the Matrix 12/Xpander/JP6/8 etc once did. Today you could get away with finding slightly dedicated MCU's such as the dsPIC and waveshapers and you've entered DSI analog territory.

/Fan of analog synths

[albpower2seq4sid]

Ok, I download dsPIC33 datasheet and it look's interesting to search, besides that I saw the site of Dave Smith Instrument and some of the devices there, but I will try to read more about pulses digitally generated and the possibility of use an CEM3396

As a complete Synth solution, CEM 3394 seems pretty good, but nobody sells it at ebay, I would try then CD4046 and CEM3396 with an exponential converter like that present at MS-02 interface from KORG, the schematic shows a linear to exp amp, and a log amp, to convert expo to linear, may be it could work?

I found it at this link:

http://www.korganalogue.net/korgms/mssermans.html

Well, the slight issue with the 4046 is that you need it to be under exponential control to be musically useful. Take a gander at the fine work of Thomas Henry who coaxes 7 octaves out of some PLL chips. Watch your brand! Matthias Herrman (Fonik) made some very nice looking PCBs a short while ago. The thing is that those make a complete VCO with it's own waveshapers. It has the nastiest sync sound I've yet to hear!

You then need to send the square-waves (and nothing else!) through the 3396 waveshapers if you want to use that IC fully. Otherwise you'll end up with a glorified VCF/VCA combo better buiit using other means.

You'd be better off if you could get direct control over the generation of square-waves for the timing of the 3396 VCO/Waveshaper. It's easy to set up a V/Oct VCO in your lab, but very much overkill for cost reasons. That's why lots of polys used timer chips under control of 8-bit micros plus several 3396's for the synth voices. It would be very expensive to use discrete VCOs, even VCO chips as the Matrix 12/Xpander/JP6/8 etc once did. Today you could get away with finding slightly dedicated MCU's such as the dsPIC and waveshapers and you've entered DSI analog territory.

/Fan of analog synths

Edited October 24, 2011 by albpower2seq4sid