My comments follow:
This was done in purpose. I have taken a look at the documents and it does not state that the crossing must be coherent across rows and columns. I could avoid the crossing on the last row only.wcass wrote: ↑One thing i noticed is that the bottom row (pin 3) does not cross any columns. All of IBM's designs have every row crossing every column exactly one time and I made sure i did that with the XTant, but I'm not sure how much difference this makes or what it does. My best guess is that it is an attempt to make all of the rows/columns as uniform as possible vis-a-vis Cx and Cp.
But I will take your advice and route it in a way that it crosses one time each column also.
You mean this -> http://deskthority.net/styles/deskthori ... target.gifI think you see what i was talking about earlier; this being difficult to do with IBM's original capacitive pad design due to the number and location of the model M rivets. You might look at some of the other capacitive pad designs that i suggested earlier in this thread that allow the rows to pass through the center of the switch rather than forcing them to always go around. At worse you will have one trace competing with a hole in the space between rows rather than two.
Yes, I read it. Very good documents. Lots of information.
The problem that I see with the alternative design is that we do not want to replace the top plate and it is not made out of metal. This means that the keyboard may be affected by noise. I am actually afraid of the 50 Hz (60 in the USA). This is why I tried to use the IBM design. Also because you have demonstrated already that can be done.
We could attach a long flat connector to the xwhatsit controller and design three PCBs (my feeling is that the triangles will work well). It will be more expensive that's the drawback.
I am thinking also to reduce the width of the X and Y traces. It will reduce the noise also.
I will create a new version with these two changes: (1) last row crossings (2) reduced width of X and Y traces
I post the two pages of the documents that you pointed that talk about routing: