BBD-MN3010 and MN3011- is a MN3101 clock necessary?

[Theo]

> Will you be able to smoothly sweep the BBD clock  frequency of the
> microcontroller (assuming you want to do things like chorus and
> flanging)?
>
It depents on the type of processor AVRs are much faster than PICs on the
same frequentie.
A PIC will do nicely but the AVRs offer more options here.
The ATtiny15 runs on a internal 1.6MHz clock,  in praxis this will do for
about 1.2 mips.
It operates in the same speed range as a 8MHz 68000!!
The one of the timers can use a internal 25MHz clock, that should be a solid
basis for smooth sweeps.

> I wonder if it would be possible to clock the microcontroller
>  from a high-speed VCO?
>
No that won't work, there would be no way to generate the constand dead time
bedween the BBD clockpulses.

Note that the uP IS the highspeed VCO, a single 8pin chip solution.
The real advantage of the uP is that it can generate all needed timing
signals, SH and BBD clock.
You can hang poti's on the analog inputs and let the uP be the LFO, ENV
Follower,...., or feed the uP a CV signal.
The internal 10bit DAC will be fast enough for CV input applications.

>Or maybe have the microcontroller operate from a
> crystal, but have an interrupt routine which toggles the BBD clock lines
> (with suitable non-overlap time) every time the microcontroller detects
> that an external VCO has put out a new pulse? Mike
>
Hang the VCO on the exsternal interupt line, responce will be whitin 4 clock
cycles (worst case).
If you use a external high speed VCO there would be no need for analog
inputs on the uP.
A much cheaper ATtiny10 or 11 will do in this case.
These can run on a exsternal crystal, 6 or 8 MHz max. the main source of
failure may be the uP boaring it self to dead ;^)
ATtiny10 and 11 have some additional sram (128 bites or so) may be handy.

The AT90S1200 ($5, 16MHz max) may also be an option, gives 15 I/O lines but
no sram,
enough power left for a soft UART though (somehow the word MIDI crosses my
mind :)   ).
Last but not least there is the AT90S2300 ($6, 10MHz), offers sram, 15 I/O
lines and a hardware UART.

Other uP will work as well o'cause, it's just me being a risk fan.


Hope this helps.
Regards Theo