Converting an IBM Multistation with an xwhatsit

Hey everyone! It's Matt here with a new wacky project :P

I recently acquired an IBM Multistation keyboard from Wingpad (who got it from alh) with the intention of actually using it unlike most. I decided to choose xwhatsit vs other controllers b/c I wanted to use a solenoid with this project :evilgeek:

The board as I got it:
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My current layout/caps (Thick PBT P70 keycpas w/ 5140 spacebar and stab used!!!)
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Here's where I am currently with the conversion:

I have traced out both PCB's - yes two. The "early" style PCB that is used on spherical cap multistation is quite different than the later nonspherical type, but use the same IC's. I have the later type, but someone with an early type should also be able to convert in basically the same fashion.

These PCB's are rather complicated :shock:

Early:
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Late:
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xwhatsit wiring diagram:
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Stock IC's
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I have the xwhatsit wired up and it is detecting keypresses, but a single key can light up the whole column/row, so I need to go back through my wiring and check for grounding/bridges. I also had to desolder these diodes that connected the rows and replace them with jumpers, in order for any keypresses to be detected.

Jumpers:
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Current wiring setup:
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Mattr567
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Unread post15 Apr 2018, 22:39

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Good work so far! Looking forward to seeing the final result!
orihalcon

Unread post18 Apr 2018, 02:42

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Good luck, one of these with the spherical caps is my absolute holy grail... I would love to get one working.

I guess replacing the controller is really the way to go for these since they do not seem to be convertible to a modern protocol with a modern layout noninvasively
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Unread post21 Apr 2018, 20:35

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So, I'll confess being confused... As I understood it, xwhatsit was designed for capacitive keyboards, not switches. I wouldn't have expected it to work at all. I wonder if the tmk/converter for pingmaster would have worked with the original controller as this almost looks like a latter version of it?

Hard to say as most people don't have the test equipment to answer that question.

Did you succeed in completely isolating all of the other circuitry on the PCB other than the matrix?

Regardless, we can help you get this working.
__red__

Unread post22 Apr 2018, 09:16

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__red__ wrote:So, I'll confess being confused... As I understood it, xwhatsit was designed for capacitive keyboards, not switches. I wouldn't have expected it to work at all. I wonder if the tmk/converter for pingmaster would have worked with the original controller as this almost looks like a latter version of it?

Hard to say as most people don't have the test equipment to answer that question.

Did you succeed in completely isolating all of the other circuitry on the PCB other than the matrix?

Regardless, we can help you get this working.

Xwhatsit works on regular switches too which is awesome mostly for the ease of configuration and solenoid adding potential :)

I believe I was the first to post a project using it for regular switches back in 2015 with a hand wired M0110. If you scroll to the bottom, I put one in an SSK as well with a solenoid:

https://geekhack.org/index.php?topic=69394.0
orihalcon

Unread post22 Apr 2018, 14:03

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I also have a SSK with Xwhatsit, sadly the solenoid output is broken.
Currently I do also a cherry mx handwire with another one, this hopefully with working solenoid output.
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Unread post22 Apr 2018, 14:55

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__red__ CS will also work on resistive keyboards. You'll just need to configure ADC to 8 bit and set thresholds to 99 (side note - should I allow thresholds up to 255? They're bytes internally..)
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Unread post22 Apr 2018, 19:48

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So how does it work with no diodes? 1kro?

... And yes, you should allow all the way up to 255... Not only in the setting of the limits but also in the status display.

Secret Santa had to "cheat" when building a handmade board last year (so he told me last year seeking support) :-)
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Unread post22 Apr 2018, 23:05

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__red__ wrote:So how does it work with no diodes? 1kro?

... And yes, you should allow all the way up to 255... Not only in the setting of the limits but also in the status display.

Secret Santa had to "cheat" when building a handmade board last year (so he told me last year seeking support) :-)

Status display is trickier, because 99 is 2 digits, and more than that is 3 digits so displays will be WIDER.

With no diodes it will work like with diodes, only with no diodes. So, you'll be able to press second key in the same row - no restrictions. You'll also be able to press a second key in another row - also no restrictions. 3rd key you gonna be careful - you don't want to create a configuration that will short rows.
Microsoft had a good article on ghosting, IIRC
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Unread postYesterday, 07:26

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__red__ wrote:So, I'll confess being confused... As I understood it, xwhatsit was designed for capacitive keyboards, not switches. I wouldn't have expected it to work at all. I wonder if the tmk/converter for pingmaster would have worked with the original controller as this almost looks like a latter version of it?

Hard to say as most people don't have the test equipment to answer that question.

Did you succeed in completely isolating all of the other circuitry on the PCB other than the matrix?

Regardless, we can help you get this working.

As it was triggering the whole column I was going through my wiring again and it might be wrong? You can see in my PCB trace pictures. This PCB looks to have more than 8 rows :(

Isolating all of the other circuitry?

I DID try the TMK Pingmaster converter, didn't work sadly.

Also this PCB is NKRO, so I should be ok in regards with diodes?

In the end it might be easier to handwire...
DMA wrote:__red__ CS will also work on resistive keyboards. You'll just need to configure ADC to 8 bit and set thresholds to 99 (side note - should I allow thresholds up to 255? They're bytes internally..)

Could this be my issue?
Mattr567
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Unread postYesterday, 07:39

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The Xwhatsit is limited in that you can only have up to 8 rows and up to 16 columns. If you are getting an entire row to light up at once your voltage threshold may be too low. Increase it slowly until you get only a single key to light up on the matrix. See where you get with that first.
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Unread postYesterday, 20:44

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Mattr567 wrote:
DMA wrote:__red__ CS will also work on resistive keyboards. You'll just need to configure ADC to 8 bit and set thresholds to 99 (side note - should I allow thresholds up to 255? They're bytes internally..)

Could this be my issue?

Nope. You're using xwhatsit, we're talking about CS.
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Mattr567 wrote:Also this PCB is NKRO, so I should be ok in regards with diodes?

Yah, I just looked again and see the diodes this time.

I just had a curious thought, and it aligns as to why you had to replace those diodes with jumpers before you saw anything. Others on the thread, please give your thoughts in my hypothesis.

I'm wondering if the rows/cols is "backwards".

All controllers strobe and sense. I don't know which way around xwhatsit is, but I'm wondering if it's backwards relative to this PCB. It's not like there's a standard or anything. That could explain the symptoms we're seeing...
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__red__ wrote:I don't know which way around xwhatsit is

It drives columns. Driving by rows is a clowny idea - i.e. mine.
DMA

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