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[Midibox AY 3 8912... ]


lemonhorse
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A minor Update (mbay38912v004.zip):

http://www.midibox.org/dokuwiki/doku.php?id=midibox_ay_3_8912

Greetings,

- Lemonhorse

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  • 5 weeks later...

Hi, and thanks for the spec/code.

Just filled myself a breadboard with a spare 8910, and uploaded 0004.

(im not using the menu or c64 kb, just bare MIDI)

CCs seem to work, but volume is odd.  I sampled and analyzed the signal using my audio interface

->

All notes sound @ -22dBFS until i mess with CC7

and when it hits the val=54-55 range the volume jumps to -7dBFS (much more acceptable)

But only for the length of the current note.

I feel like some values are getting overwritten somehow, but i cant figure it out from the code.

The envelope CCs dont do a thing, but Noise and tones can be turned on and off ok, and the tuning is alright

so im a bit puzzled.

I took the 8910/8912 sheets and im pullup'ing more things than 8912 (since theres more on the 8910)

But before i go on i just wanted to ask if you had an idea of what i should check first...

3973_IMG_1527_jpgb7b0c46dbf376485d1d6c36

3973_IMG_1527_jpgb7b0c46dbf376485d1d6c36

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Hi vedge the first 8910  :)!,

CCs seem to work, but volume is odd.

The VELOCITY TO VOLUME TONE ABC MODE is ON by default (MIDIBox AY 3 8912 - VOLUME MENU)

...I feel like some values are getting overwritten somehow

Right - the CC Value will only take effect if the VELOCITY and the ENVELOPE mode is off.

Here you'll find some Background:

http://www.midibox.org/dokuwiki/doku.php?id=midibox_ay_3_8912_volume

... im not using the menu or c64 kb

I want to implement cc switches for enable/disable the VELOCITY and ENVELOPE mode. Sorry, for now You'll need the Keyboard/LCD.

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Thanks Lemonhorse,

I want to implement cc switches for enable/disable the VELOCITY and ENVELOPE mode. Sorry, for now You'll need the Keyboard/LCD.

OK! Just wanted to check if the behavior i was experiencing wasn't due to bad wiring/components first.

If it can be explained by the current requirement for the C64kb in 0004, i know where to look next.

More progress reports! soon...

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  • 1 month later...

Changes @ V0.05: Rudimentary Pitch Bend implementation, some smal improvements …

http://www.midibox.org/dokuwiki/midibox_ay_3_8912

Another interesting AY chip projecct:

-hard plAYer- an 8 bit tunes hardware player

http://tolaemon.com/hplayer/

And new Stuff to think about:

http://leonard.oxg.free.fr/ymformat.html

;)

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  • 1 month later...

hi Sirkit,

hope You'll build a MIDIBox AY with keyb. and a 4x16 LCD - for I need a firmware tester! ;-)

project state (just to let you know):

for a better code-management i started to use subversion (on my local linux machine) - the next ay step will be to implement the MIDIBox AY "Patch Menu" - name, write and load an internal ay sound patch (by using the eeprom of the 18F452, bankstick support will come later) - I'm afraid this will take some time (because i'm a spare time newby programmer, and there is not enough spare time...  :( ;)  ).

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great project, lemonhorse!!

i'd like to try to build that synth too. but it seems as if i had thrown away my old C64 after salvaging its 8580, stupid but i can't find it anymore.

so i wonder whether the C64 keyboard could be replaced by a something like a self built button-matrix?

i'm sure it would take some time for me to build and to understand... but it's a good sounding synth!

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hi rosch,

...so i wonder whether the C64 keyboard could be replaced

a good point, it's not so easy to have a c64 keyboard at hand in these times.

i actually thought about a "at keyboard option" - maybe someone is willing to design a at keyboard midibox-interface?!

here are some starting points:

http://www.subfrequenz.net/linklist/index.php/topic,56.0.html

i suppose a self made button-matrix (c64 keyboard replica) is not easy to create - or would you like to try (should we start such a project) ?

:)

How to drive a button matrix of 8x8 = 64 buttons. See also this connection diagram:

http://www.ucapps.de/mbhp/mbhp_scan_matrix1.pdf

http://www.c64-wiki.de/index.php/ASCII-Code (sorry some information is in german)

http://en.wikipedia.org/wiki/PETSCII

http://sta.c64.org/cbm64petkey.html

http://www.zimmers.net/anonftp/pub/cbm/manuals/anthology/p073.jpg

http://www.zimmers.net/anonftp/pub/cbm/manuals/anthology/p074.jpg

C64 CIRCUIT THEORY

http://www.devili.iki.fi/Computers/Commodore/C64/Service_Manual/Page_12.html

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i suppose a self made button-matrix (c64 keyboard replica) is not easy to create - or would you like to try (should we start such a project) ?

i would like to learn how to do that. but i wouldn't call me the right person to start such a project with because i actually don't know anything about it. at the moment i'm still trying to understand the basics (messing around with my sid). so if even you regard it as not easy to create then i'd think looking for another C64 keyboard and trying to build it as recommended would still be difficult enough for me, at least at the moment.

but i can try it of course but that will take a long time as far as i know me, and probably very stupid questions from my side.  :)

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hi Sirkit,

hope You'll build a MIDIBox AY with keyb. and a 4x16 LCD - for I need a firmware tester! ;-)

I should be ordering everything tomorrow!  I already have my keyboard.  I'm gonna get my AY through this site.  http://www.arcadechips.com/product_info.php?cPath=27_22&products_id=111

Hope it works!

Also with that HardplAYer, would you be interested in playing YM's off this box (like how the sid can play sid files)?  Yours could be a lot more functional. A full keyboard!  The HardplAYer had some interesting features like looping and such.  Cheers!

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I did a group buy for AY chips through this site. When Lemonhorse received his chips from the group buy, he discovered that the chips were unable to add NOISE to Tone A, B or C.

The chips received had these markings: AY38912A/P 9151 CCA

Before you order, you may want to ask the seller to give you the markings on the chips and compare them to the markings listed above to ensure you don't get the same issue. I haven't been able to prove it out, since I haven't built my AY midibox yet, but I believe all the chips in the group buy have this issue, simply because all of the chips received by Lemonhorse had this issue. This may not be a "flaw" as much as it is a design for this particular version of the chip. I'm just not sure. But, it is a bummer that I have a bunch of chips that won't be used to their full potential. However, I still plan on using these chips! So, just do your homework with the seller before you order...

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