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Subject: Re: [korgpolyex] New Voice Chips?

From: Michael Hawkins <korgpolyex800@...>
Date: 2014-05-31


I am also looking at the STM32F107RC. ARM 32-bit-M3 running at 72Mhz, 256K flash, 64K RAM with 2x12 bit D/A converters, 80 I/O ports and tons of other good stuff. All for about 10 bucks.

I also happen to be working on another project that uses the same device. So I have to set up the development environment and get familiar writing code for it anyway.

Mike


On Friday, May 30, 2014 11:45 AM, "bperkins211@... [korgpolyex]" <korgpolyex@yahoogroups.com> wrote:


 
Don't know why you'd bother with PIC, the toolchain is shite and they are electrically "fragile". If you use a low-end ARM chip you may need to do something to convert between 5V and 3.3V logic, but you'll have enough grunt for all eight voices.

Doing two voices and all four outputs for square and saw ought to be doable in a single atmega 328.

Use a PWM output to generate the "analogue" output instead of an R/2R DAC. Use the counter for the PWM to trigger the sample calculation at around 32kHz and allow it to run asynchronously from the control loop. When the PWM rolls over it'll call an ISR that you use to load the comparison register with the calculated sample value.

Pish easy.

--
Gordonjcp MM0YEQ



I suggested the PIC since it is the only uC I have any kind of experience with and currently studying, for now..  I was trying to offer ANY help on this attempt to revoice the HAWK.

Your suggestion sounds nice.  I remember you posted something on this and some code as well awhile back.
Is the PWM outputs from it require any filtering at all?

Do you have any docs to point to on using wavetables on a ARM chip?  Can you maybe lend more detailed advice on this?
I take it to get 8 voices total, that we'd need two atmega 328's?

I'd like to know more about any chip used for Arduino projects anyway...
I am looking to start building quadcopters and other UAV's using some of the open source Flight Controllers available like 3dRobotics APM.

~Blaine