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Clnilsen

Looking for a working CX85->USB connector

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I really want to connect my CX85 keypad to my work windows laptop via USB to use for spreadsheets. I've done some searches and found some people who have done this, but no real instructions. Anyone have a working adapter board / kit / dongle they would be willing to part with to connect a CX85 -> USB that works simply?? Thanks!

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Unless you are specifically needing it to have the retro look, there are actual non-Atari USB numeric keypads available.

 

As to your request. I don't recall ever seeing a converter to take the joystick output of the Atari keypad and converting that to USB, but if there were I would love to see something about it.

 

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There are USB encoders used regularly for MAME setups and arcade control boards. Windows (as an example) “sees” them as HID “Human Interface Device” items and maps the inputs to keypresses. It’s conceivable you could wire up a 9-pin joystick connector and map the signals to whatever simulated keypresses you want, but it will take some effort to get it working the way you want. 

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I don't currently own a CX85, but if I get one I can test it out with the Raphnet adapter I have.

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Technical notes http://www.atarimania.com/documents/Atari_CX85_Numerical_Keypad_Technical_Reference_Notes.pdf

 

A USB adaptor project here https://geekhack.org/index.php?topic=51321.0

 

The noteworthy thing is that you can't just read the pad straight up - the BPOT signal valid trails the STRIG by 150 microseconds so might have to be accounted for by any interface software or firmware - the Atari uses the capacitor dump transistors (in fast scan mode?) - if an external interface was using digital values then possibly that signal becomes valid sooner.

Edited by Rybags

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On 2/26/2020 at 4:54 AM, Goochman said:

Would a Stelladaptor work with the CX85?

Stelladaptor no, but my 2600 D9 supports it.  Note it works as joystick buttons - use a joy-2-key app if you need keyboard keys.

 

Tom

http://2600-daptor.com/

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34 minutes ago, dualcam said:

Stelladaptor no, but my 2600 D9 supports it.  Note it works as joystick buttons - use a joy-2-key app if you need keyboard keys.

 

Tom

http://2600-daptor.com/

Strictly out of curiosity, Tom, why won’t Stelladaptor work if it’s just sending joystick button “presses”?

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Posted (edited)
23 hours ago, jamm said:

Strictly out of curiosity, Tom, why won’t Stelladaptor work if it’s just sending joystick button “presses”?

The "it works as joystick buttons" was in reference to my 2600 D9, not the CX85.  The 2600 D9 shows to the USB host as USB joystick, with the CX85 keys mapped to the USB joystick buttons. 

 

The CX85 uses some of the DB9 pins differently than the 2600 controllers.  There is a handshake with a ready signal, and a bit pattern to decode which CX85 key is pressed.  The Stelladaptor does not know about any of this.

 

Tom

http://2600-daptor.com/

Edited by dualcam
clarify

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I finally got one, I need to test it with the raphnet DB9 adapter and see if it works.  I usually just test with the jstest-gtk program under Linux, so not sure what it'll do outside of act like a joystick?  But would be cool to use that style of keypad for something, especially if I could attach it to my work laptop.

 

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3 hours ago, dualcam said:

The CX85 uses some of the DB9 pins differently than the 2600 controllers.  There is a handshake with a ready signal, and a bit pattern to decode which CX85 key is pressed.  The Stelladaptor does not know about any of this.

I see - thanks for the explanation.

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It also uses POT B.

 

Here's the schematic for the CX85, which includes the truth table for the output.  You need to read POTB in order to differentiate between '0' & 'F1 (ESC)'.

 

 

atari_cx85_field_service_manual_0008.jp2&scale=8&rotate=0

 

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"Atari CX85 Numerical Keypad Technical Reference Notes" PDF is on the 'net.  Includes that schematic and how to read the CX85.

 

My reference to "joystick buttons" was that the 2600-D9 represents as a USB joystick to the host, not the controller jack pins.

 

Tom

http://2600-daptor.com/

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