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Messages - norbim1

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PreenFM2 / Re: New beta firmware 2.00 beta 1 (August 28th)
« on: September 04, 2015, 10:27:57 AM »
That's interesting i modified slightly the enveloppes.

Hi Xavier,

By further analyzing I realized, that it is now the correct behavior according the envelope time and level values! So the enhancement showed me, that there were wrong parameters in my sound, but it didn't turn out in earlier versions. So thanks a lot, it's way better than before!

By the way the bootloader works the same way as on original HW, I'm using the "Access Usb" - "flash from USB" method to upgrade the FW.


PreenFM2 / Re: New beta firmware 2.00 beta 1 (August 28th)
« on: September 03, 2015, 09:19:59 PM »

I upgraded my Discovery port with the new poly firmware, and it definitely sounds better then before! It's a Huge step I think. As I tested it, I noticed a small difference in an organ voice. I think, that the difference related to OP envelope. If I set both the sustain and release levels to zero, the release time has some effect on the sound, but I think it shouldn't have to be. Maybe it is a bug in my port, can somebody please check this on an original PreenFM2 hardware?

Thanks, Norbim

PreenFM2 / Re: Stm32F4Discovery port
« on: December 23, 2014, 04:20:51 PM »
I've never tried it without LCD. The control surface works exactly the same way as the original pFM2, I didn't change it.
Related to build errors I'm sorry, but I'm not an expert in it.

PreenFM2 / Re: Stm32F4Discovery port
« on: December 22, 2014, 09:29:59 PM »
I'm using Eclips and MidiBox toolchain without any problem.
Anyway here is the binaries. I've made only the overclocked version for Stm32F4Discovery, so bootloader and overclocked only.

PreenFM2 / Re: Stm32F4Discovery port
« on: August 13, 2014, 03:20:00 PM »
Thanks a lot, but it's definitely your fantastic project's merit.
I'll try to keep the fork sync with the upstream repository.

PreenFM2 / Re: Stm32F4Discovery port
« on: August 12, 2014, 09:47:14 PM »
Schematic and a suggested veroboard wiring:

PreenFM2 / Re: Stm32F4Discovery port
« on: August 12, 2014, 09:45:45 PM »
Some pics about the gadget:

PreenFM2 / Re: Stm32F4Discovery port
« on: August 12, 2014, 12:24:40 PM »

I've managed to fork it and merged with the latest 1.04 fw:

- STM32F4Discovery module based PreenFM2
- uses the onboard I2S codec, audio data send through DMA
- the CS buttons and encoders are directly connected to the IO ports of the module
- made some minor changes to the display driver, (I use a cheaper OLED module: Raystar REC002004AYPP5N00000)

I'll post the schematic and some pics of my newly built module soon. It was built on veroboard, so no PCB design has been made for it.

Regards Norbert

PreenFM2 / Re: Stm32F4Discovery port
« on: June 27, 2014, 02:49:50 PM »
Hi Xavier,

I'm just a hobbyist so I  don't have registered yet to Github and I'm quite new with it.
The CS part of my project is still left. As soon as it's ready, i'll fork it.

Thanks, Norbert

PreenFM2 / Re: Stm32F4Discovery port
« on: June 27, 2014, 09:50:13 AM »
It works! Thanks again for the info.

PreenFM2 / Re: Stm32F4Discovery port
« on: June 26, 2014, 02:59:22 PM »
Thanks for the info. I found the offset, but didn't found the scale. I'll try it today evening.

Yes, the codec accepts padded 32 bit samples, the 24 bit part has to be justified to the right. Actually the codec accepts 2*16bit words for one stereo side sample, so I need to swap the half words of the 32 bit int when filling the DMA buffer.

PreenFM2 / Stm32F4Discovery port
« on: June 26, 2014, 11:10:19 AM »

First of all thank you Xavier for this wonderful project and making it open source.

I've started to port the project to the STM32F4Discovery board, which has a nice audio codec on board. I haven't built the control surface yet, but in the current state I'm able to play notes from USB midi. The board have enough free IO pins left to direct connect the CS buttons and enc-s, so I'll try to eliminate the cs s/p converters too.
To use the onboard I2S audio codec I changed the Systic interrupt to DMA int. Currently I'm using 32 samples long DMA buffer, and it works perfectly. In that way the DMA int is fired only at every 16th sample.
I'm wondering if I can use the full 24 bit resolution of the codec. As far as I see the sample block contains 18 bit normalized uint samples, but I couldn't find where it is normalized. I plan to change the timbre summing at the end of the buildNewSampleBlock(), but I'm sure that it has a better place for it.
Would You mind helping me with the place of the "float to 18 bit" normalizing?

Thank's a lot,

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