[sdiy] Arpeggiator1 / Arduino UNO

[Roman Sowa]

And when you decide to add glide in software, then what? Oh, you already 
answered that, a chip...
Or this can be better done as gated analog glide like for example in MC202.

I had this idea of using 2 DACs in MIDI2CV module before, but it all 
collapses when Pitch Bend needs to be added. At the end it turned out 
cheaper/easier/better to use regular 16bit DAC.

Roman

W dniu 2015-04-10 o 10:26, Rick Jansen pisze:
>
> No idea, and I don't care :-) All I want is 12 discrete voltages per
> octave. As far as I can tell, without actually measuring, the voltages
> are reached quick enough, and are repeatable.
>
> The arpeggiator code has a list of 48 values, one for each pitch. You
> can tweak each value to obtain the perfect pitch, eh, voltage.
>
> So, this is not a DAC where changes from 0x40FF to 0x4100 or 0x4000 to
> 0x3FFF are an issue. And if they are I'll use a chip.
>
> I'm quite happy to have found this componentless solution, as I did not
> have a DAC (well, I have an old ZN426), and it was Easter, so no shops
> were open..
>
> rick
>
>
> On 10/04/2015 10:08, Roman Sowa wrote:
>> How does your 8+8 bit PWM DAC perform in terms of DNL at the MSB
>> boundary? I mean when for example it goes from 40FFh to 4100h, as well
>> 4000h to 3FFF.
>>
>> Roman
>>
>> PS. I put so many tehnical sounding mumbo jumbo in first sentence that
>> it sounds even funny :)
>>
>> W dniu 2015-04-10 o 01:03, Rick Jansen pisze:
>>> Hi all,
>>>
>>> Well, at long last I'm a bit back to synth-diy-ing. Here is my first
>>> Arduino UNO based project: an arpeggiator:
>>> <http://dropmix.xs4all.nl/rick/Emusic/Arpeggiator1/>
>>>
>>> It serves two purposes: 1. getting to know the Arduino, and 2. finally
>>> using that 1-octave piece of keyboard that was in a box for 20 years.
>>>
>>> It's still in the breadboard phase, as a tryout for the upcoming
>>> sequencer, but it works, and I'm having a lot of fun with it.
>>>
>>> A longer writeup, images and sketch are in the web page
>>>
>>>    <http://dropmix.xs4all.nl/rick/Emusic/Arpeggiator1/>
>>>
>>> Here are some keywords:
>>>
>>> - I2C 8574 ic's as in/out expander: 2 chips to read the 12-key 1-octave
>>> keyboard, interrupt based; 4 bits spare;
>>> - I2C 8574 ic's as LED outputs: 12 LEDs, one per key, displaying the
>>> note playing as a sequencer; 4 bits spare;
>>> - Can easily be expanded to 64 keys in + 64 LEDs out, or 128 things in
>>> or out, or whatever. (I2C is great!)
>>>
>>> - ~16 bit "DAC" without a DAC: using two PWM pins combined, and
>>> RC-filters, to produce the control voltage;
>>> - gate signal; gate may be shorter than the note duration for
>>> "staccato", etc;
>>>
>>> - TimerOne interrupt based timing, 120BPM, 24 ppqn, like midi does, if I
>>> understand that correctly;
>>>
>>> - sequence mode: up / down / up-down / random ;
>>>
>>> - For each note there's a pitch, a duration and a gate duration,
>>> internally, although for the arpeggiator note and gate duration are
>>> currently fixed value (all quarter notes, @ 24 ppqn)
>>>
>>> - Operation:
>>> 1. press START
>>> 2. press one or more keys of the keyboard
>>> 3. while you keep the keys pressed the machine loops through the
>>> corresponding notes
>>> 4. press STORE to store the melody; you can now release the keys
>>> ...
>>> 8289. press STOP
>>>
>>> rick
>>>
>>>
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>>
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>
>