Replacement Keyboard Project Update

Discuss the CreatiVision hardware: models, revisions, fixing, hacking and modding.
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Scouter3d
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Re: Replacement Keyboard Project Update

Post by Scouter3d » Mon Apr 05, 2021 12:42 pm

Hi,

Done a bit of testing:
With 1x CD4066 (4 switches) hooked up to the Arduino UNO and to Pins 1,2,3,4 and 10 of the left CV controller i was able send Keypresses :0)
with only the 4 switches the CV recognizes the characters "2,3,6,SHIFT,",#,&" :0) see image of endless keystroke loop with errors in CV Basic every time the line gets too long ;0) and reflexion of my window :0)
4066_loop.jpg
using DC4066s instead of the MT8808 may become my preferred way... as they are readily available, very cheap and the arduino code may be faster and smaller...

Even so, here is how i will try to connect the MT8808 (when it arrives from china in a few weeks :0()

WARNING: WITH THIS HOOKUP OF THE MT8808 YOU CAN DAMAGE THE CREATIVISION!
MT8808_hookup_small.jpg
Cheers, TOM:0)
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Last edited by Scouter3d on Mon Apr 12, 2021 5:28 am, edited 1 time in total.
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cheshirenoir
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Re: Replacement Keyboard Project Update

Post by cheshirenoir » Tue Apr 06, 2021 9:47 am

Aaah clever! I didn't spot that we only had to parse the 4 lines if we bridged the left and right pins.

I'll redo it in KiCAD tonight. Maybe I'll even add the Arduino :-D
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Scouter3d
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Re: Replacement Keyboard Project Update

Post by Scouter3d » Tue Apr 06, 2021 11:34 am

Hi Chesh,

the left and right pins are allready internaly bridged! (in fact they are the same 8 lines, they are only present on both handsets because they are physically seperated)

Cheers, TOM:0)
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Scouter3d
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Re: Replacement Keyboard Project Update

Post by Scouter3d » Mon Apr 12, 2021 5:26 am

Hi, a quick warning! the solution with one MT8808 is possibly harmful to the CV! (i burned two PIA chips inside the CV...) so please do not try this at home :0)
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Mobsie
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Re: Replacement Keyboard Project Update

Post by Mobsie » Tue Apr 13, 2021 9:35 am

Oh no, hopefully easy to fix for you
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Scouter3d
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Re: Replacement Keyboard Project Update

Post by Scouter3d » Tue Apr 13, 2021 12:33 pm

Mobsie wrote:
Tue Apr 13, 2021 9:35 am
Oh no, hopefully easy to fix for you
Hi Mobsie, now i have a socket in my CV for easy replacement of the PIA :0) (luckily i had 3 spare PIAs)
Greetings, TOM:0)
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cheshirenoir
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Re: Replacement Keyboard Project Update

Post by cheshirenoir » Thu Apr 15, 2021 1:16 am

Oww! Any idea what went wrong? The design logic you used looked "sane". You're just "shorting together" pins.

Cheers!

Chesh.
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Scouter3d
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Re: Replacement Keyboard Project Update

Post by Scouter3d » Thu Apr 15, 2021 5:43 am

cheshirenoir wrote:
Thu Apr 15, 2021 1:16 am
Oww! Any idea what went wrong? The design logic you used looked "sane". You're just "shorting together" pins.

Cheers!

Chesh.
Hi Chesh,

here is my guess what went wrong:
On the CV the 8 left and right controller-PB port lines are the same, but they are also seperated from each other internally by diodes, so no high PA line can get thru from one side to the other ... using only the 8 lines on one side to send all the codes can create some "killer keycombinations" where three "high" PA lines connect thru the MT8808 to one low PA line (which than burns...) ... (one the real keyboard at the most 1 high PA line can be connected to 1 low PA line and even that is bad... like pressing both firebuttons or Shift + CTRL at the same time)

I am looking into seperating the PA lines from each other using schottky diodes (at least it worked yesterday, today a few keys are not working, could be a "wobbly" breadboard or something else... at least the PIA is not fried again, as the normal CV keyboard still works fine...)

cheers, TOM:0)
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cheshirenoir
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Re: Replacement Keyboard Project Update

Post by cheshirenoir » Mon Apr 19, 2021 7:40 am

Well, my 8808s just arrived :-)

I'll have a "play" later.

Chesh
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Scouter3d
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Re: Replacement Keyboard Project Update

Post by Scouter3d » Mon Apr 19, 2021 8:12 am

Hi Chesh,

great news!

Good luck with your "play" :0) - Please be careful..
I killed 2 PIAs in the CV during testing, my version with diodes for protection did also fail :0( (Or as Edison said: “I have not failed. I've just found 10,000 ways that won't work.” )

At the moment a version with 2x MT8808 looks the most promissing (and only way if the Joysticks are added or passed thru. it allready works even with different PS/2 Keyboard language support) but i have to test it thoroughly and try to burn a PIA again (or hopefuly NOT burn the PIA :0))

Im my recent design i use both MT8808s inputs "parallel" but the outputs are split left + right: 1 MT8808 is connected to the "left" controllerport and the 2. MT is connected to the right port, that way the PA lines from left + right controllerport won´t short inside a MT...
When the design has hopefully proven save for the CV, i will post a schematic...

Cheers, TOM:0)
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