Honeywell Micro Switch Reverse Engineering and Conversion thread

Firebolt1914

15 Dec 2015, 18:37

Some of you may have seen my Wang keyboard. I am going to attempt to convert it to USB. I will find out if it is 2KRO and report back.

Anyways, what logic analyzer is recommended?

Also, should I do a controller swap or should I get wires connected to the connector?
Last edited by Firebolt1914 on 15 Feb 2016, 20:04, edited 1 time in total.

Engicoder

15 Dec 2015, 18:47

I don't think I've seen your wang :shock: , but I like the Saleae Logic series. They are simple to use and the software is nice. An oscilloscope is helpful as well. Sometimes a scope will catch details that are hidden from a logic analyzer.

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seebart
Offtopicthority Instigator

15 Dec 2015, 19:05

His Wang is old and bulky, I've seen it! :lol: XMIT recently got one just like that.

http://deskthority.net/keyboards-f2/wan ... hilit=wang

Good link btw Engicoder.

Engicoder

15 Dec 2015, 19:07

I feel like and idiot, but the wang jokes are irresistible.

Firebolt1914

15 Dec 2015, 19:16

Engicoder wrote: I don't think I've seen your wang :shock: , but I like the Saleae Logic series. They are simple to use and the software is nice. An oscilloscope is helpful as well. Sometimes a scope will catch details that are hidden from a logic analyzer.
I have access to an oscilloscope albeit a bad one.

Would a Logic 4 be suitable or should I just go for the 8?

Engicoder

15 Dec 2015, 19:53

The 4 will be enough for most serially driven keyboards (i.e. XT/AT/PS/2/ASCII) but the 8 would be useful for externally strobed keyboards.

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XMIT
[ XMIT ]

15 Dec 2015, 23:01

Turns out I'm planning to convert mine to USB as well. It's in the mail, should be here for the weekend.

The Saleae are really nice but you can also get cheap Saleae knockoffs for about one twentieth the price that work with the Saleae software.

Sorry for the quick post, I'll give a much more substantial update once the keyboard is here. I'm hoping to convert mine to USB with NKRO and to move some switches to make an inverted-T arrow cluster. Should be fun.

Can you post more photos of yours when you get a chance? I'd like one photo with all the key caps in place.

Firebolt1914

16 Dec 2015, 00:07

Currently it is completely disassembled. I'll possibly get a picture with the keycaps all layed out. I may also have a picture with all the keycaps somewhere.

What company is your hall effect from? From dorkvader's testing, most 'normal' hall effect boards have 2KRO. My other two hall effects are 1KRO however.

I'm planning on converting the keyboard to USB and possibly getting the solenoid to work as well; that would be amazing!

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XMIT
[ XMIT ]

16 Dec 2015, 03:14

I think I ordered the same Wang keyboard you have.

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Muirium
µ

16 Dec 2015, 07:57

All this talk of getting hands on wangs is making it difficult to drink my coffee!

2KRO is the devil. Well, when poorly allocated. IBM did it right on the SSK, where the modifiers get priority, yet they fucked up good on the terminal M122. Nothing much you can do with a flawed matrix, other than replace it entirely.

But that's a lot of quality time with your wang, and they don't all like being handled that way…

andrewjoy

16 Dec 2015, 10:30

Nothing wrong with wang jokes :P

This should help you analyse your wang

http://www.ebay.co.uk/itm/Hewlett-Packa ... Sw~bFWI~Cr

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XMIT
[ XMIT ]

18 Dec 2015, 14:41

It's here! It's gorgeous! Complete metal casing, unlike the plastic of its foam-and-foil brother. I've never had USPS deliver something before 8am. Wow.
DSC_6886.JPG
DSC_6886.JPG (451.13 KiB) Viewed 3610 times
Wang terminal keyboard, Micro Switch Hall effect

Expect a full disassembly and reverse engineering for this one, it's one of the nicest keyboards I've ever seen! A full sculpted spherical double shot Hall effect board with a heavy metal casing in an almost perfect PC compatible layout. Wow.

andrewjoy

18 Dec 2015, 15:09

That wang is quite big.

Would you keep your wang at home or take it work and show it off ?

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chzel

18 Dec 2015, 15:11

Nice wang! Just be careful swinging it around!

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scottc

18 Dec 2015, 15:11

I've never been so happy to see an unexpected picture of a Wang before. Nice catch, XMIT.

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klikkyklik

18 Dec 2015, 15:13

Looks like you wouldn't even have to worry about leaving your Wang in the sun and having it turn yellow!

andrewjoy

18 Dec 2015, 15:15

Well grey ABS does yellow to be fair but you just wont notice it.

Thinking on that , i know its the bromide that oxidises but i wonder why this does not happen to PBT , do they not have the bromide ( fire retardent) in them ? Or do they use another form of fire retardent ?

Firebolt1914

18 Dec 2015, 16:20

I was working with dfj: we can't seem to figure out how the controller (the mess of chips and resistors) works yet. I am currently writing up a spreadsheet of where on the chips the switches output to.

The 3 744148s take 8 inputs and outputs 3. The 7408N is a quadruple 2 input and gate.

I have no idea what any of these do or are too well. The switches' first output which is the second pin from the top outputs to the third 744148 on a specific pin for the whole row (will edit if incorrect.) The second output of the switch goes to the first two 744148s in a specific pattern. There is only one output per pin per row.

This is all I know for now, however the 744148s connect to the and gates.

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XMIT
[ XMIT ]

18 Dec 2015, 17:12

Are you chatting with dfj on IRC? I may join you there in a few hours. I was thinking of taking my board to the TechShop today for some reverse engineering fun. They have some nicer logic analyzers than I do.

I know it's tedious but schematics would be really helpful. I'm planning to hand draw some, snap some photos and share them here. This is what lab notebooks are for.

Mine also needs a good cleaning, some of the switches are sticking. Not that Hall effect switches go bad (well maybe if you over-voltage them) but if absolutely necessary I may be able to cannibalize another board for switches and parts. I really hope it does not come to this.

Firebolt1914

18 Dec 2015, 18:10

XMIT wrote: Are you chatting with dfj on IRC? I may join you there in a few hours. I was thinking of taking my board to the TechShop today for some reverse engineering fun. They have some nicer logic analyzers than I do.

I know it's tedious but schematics would be really helpful. I'm planning to hand draw some, snap some photos and share them here. This is what lab notebooks are for.

Mine also needs a good cleaning, some of the switches are sticking. Not that Hall effect switches go bad (well maybe if you over-voltage them) but if absolutely necessary I may be able to cannibalize another board for switches and parts. I really hope it does not come to this.
My switches are very scratchy; I have taken them all off, and will eventually spray them with CorrosionX once I find out how to convert this keyboard.

I have no schematics yet, but I will upload my spreadsheet soon tm.

BTW, here is a PDF of a brochure of the VS workstations: https://ia801601.us.archive.org/9/items ... _Dec82.pdf

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XMIT
[ XMIT ]

18 Dec 2015, 23:24

Life bites again. I've only gotten as far as removing key caps, making a note of what types of switches go where, and taking some photos. I'll see what I can do over the weekend but I probably won't get back to this until Tuesday.

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seebart
Offtopicthority Instigator

18 Dec 2015, 23:30

XMIT wrote: It's here! It's gorgeous! Complete metal casing, unlike the plastic of its foam-and-foil brother. I've never had USPS deliver something before 8am. Wow.Expect a full disassembly and reverse engineering for this one, it's one of the nicest keyboards I've ever seen! A full sculpted spherical double shot Hall effect board with a heavy metal casing in an almost perfect PC compatible layout. Wow.
Nice one XMIT, congrats! Looking foreward to your review.

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XMIT
[ XMIT ]

18 Dec 2015, 23:36

Oh this will be one better: full schematics, documentation of switch properties, the works.

TechShop has air lines that run through the building. I must say, cleaning a board with central compressed air is *amazing*.

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seebart
Offtopicthority Instigator

18 Dec 2015, 23:43

XMIT wrote: Oh this will be one better: full schematics, documentation of switch properties, the works.

TechShop has air lines that run through the building. I must say, cleaning a board with central compressed air is *amazing*.
I bet, sounds like fun. Of course it will get a wiki page also.

Firebolt1914

19 Dec 2015, 00:04

I'm possibly going to run this thing through a shoddy logic analyzer (my arduino mega) tonight.

I found out that the connector socket on the bottom of the PCB has 4 grounds and 2 power inputs... Not sure if it would work with only 1 5V going through it and 1 gnd.

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XMIT
[ XMIT ]

19 Dec 2015, 00:12

The board itself does not appear to have a controller. All I see are four ICs with 7400 series logic: one 7408 and three 74148s. It seems to use a simple row-column arrangement for the switches.

So, it looks like you could keep the original cable, and attach a controller to it, to drive the MUXes directly.

Does yours have a solenoid too? Mine does. :o

That's all for now.

Firebolt1914

19 Dec 2015, 02:42

Yes, mine has a solenoid. I will try to get that working as well once I get the board fixed.

Is the bottom of your keyboard's case metal? Mine is some sort of plastic, while the top is metal.

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XMIT
[ XMIT ]

19 Dec 2015, 21:01

Reverse engineering continues.

This afternoon I had a chance to spend some time tracing continuity on the board and assigning some functions to some pins.

The board uses a cable with 24-pin Amphenol connector to the terminal, and a 24-pin DIP socket connector on the PCB. The cable is straight through: pin n on the Amphenol connector corresponds to pin n on the DIP socket.

I can confirm these pin assignments:

Vcc: 2, 3
GND: 4, 6, 8, 10

As noted earlier there is some 7400 series logic on the board:

7408 - Quad 2-input AND gate
http://www.ti.com/lit/ds/symlink/sn7408.pdf

74148 - 8 Line to 3 Line Priority Encoder (8 data lines to 3-line binary/octal)
http://www.ti.com/lit/ds/symlink/sn74148.pdf

These were mostly helpful to figure out exactly where Vcc and GND were. I'm still working on a schematic of the board to figure out just how much work a replacement controller will need to do. My current thinking is to write a patch against TMK to support this board, and to connect a Teensy to either the keyboard PCB, or the end of the existing cable.

This board may use a fair amount of power and may require an additional power supply. I don't know just how much power these Hall effect switches will use.

Most importantly, I figured out some of the pinouts of the Hall effect switches themselves. As viewed from the typist's point of view, the top pin (furthest from the Space bar) is Vcc, and the bottom pin (closest to the Space bar) is GND.

I'm not exactly sure how sensing works on the two middle pins. It will be helpful for me to re-read "Chapter 4: Electrical Considerations" of the application guide here:

http://sensing.honeywell.com/honeywell- ... 5-2-en.pdf

According to the Wiki (specifically, according to an edit Mejeep made on 2014009-03) these are "dual open-collector outputs". So, presumably, there are pull-up resistors on the board (there are a number of 6.8k resistors along the top edge of the board).

http://deskthority.net/wiki/Honeywell_Hall_Effect

Does anyone have a favorite circuit drawing package? I seem to recall there is some LaTeX extension for this.

Firebolt1914

19 Dec 2015, 21:26

I use kicad for designing circuits. As with power, I think it is possible to power it over usb as hall effect switches use 5V.

According to dfj there are indeed pull up resistors. There are at least pull ups going to the AND gate. I think the hall effect switches output a high signal on both. I have yet to test this theory.

We are close to finding out where on the connector is needed to be analyzed. We have the outputs of the AND gate to the connector. These are most likely the signals required to get keystrokes.

Firebolt1914

21 Dec 2015, 20:24

I think I have the outputs on the connector. I attempted to power it with an arduino, but the voltage drops to 4.3v, so it's not working :(

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