7i84 - matrix keypad possible?

I'm reading the matrix_kb.comp description and it appears that this comp isn't necessarily limited to 7i73's.

Just wanted to confirm that it's possible to set up a 4x8 matrix on a 7i84?  I've got a 7i73, but using the 7i84 would make wiring and related issues much easier for me.

Edit...

Question 2 - if the 7i84 is put in software process mode 2 and I'm only using one encoder input pair (I-16 & I-17) for an MPG, can I still use the other pair (I-18 & I-19) for general purpose inputs?

Thx,
Ralph

It should be possible to use a 7I84 with the matrix_kb comp
You would need to add diodes at the row/column intersections if
you expect valid outputs if more than one key is pressed at once.

The process modes do not affect the normal digital input operation
so both the MPG and analog input pins are always usable as digital
inputs with the normal (~ 1/2 field voltage) input thresholds.

Diodes are on the shopping list.

Final Q... columns connected to inputs, rows to outputs?

Yes, it looks like the matrix_kb comp drives the rows are reads the columns

Yes, the matrix_kb component suffered feature-creep and in retrospect should have been two separate components.

In one mode it scans rows and columns to scan codes, and in another it converts scancodes to HAL pins.

So, yes, it can be used to wire up anything (including a parport) to a matrix keyboard.

Thanks Andy.

You wouldn't happen to know where I can find an example of the 'optional scan-generation mode'?  Since I'm not using an separate driver mentioned in the first mode, I suspect I need the other mode.

If its not clear from the manual page:

loadrt matrix_kb config=4x8s

will create a 4x8 matrix (4 row output pins and 8 column input pins)

Revisiting this question as I'm working up a wiring diagram and I just had an 'uh-oh' moment...

I've got a 7i84D - sinking outputs.  Will this still drive a matrix keypad?  My understanding is that LCNC cycles through the outputs and inputs and looks for a state change and figures out the right key from the I/O combo.

If the inputs and outputs are both sinking, there's nothing to drive any of the pins...?

You might be able to invert the outputs (software) and pull them up (hardware) to make it work.
But it might be easier to use the 7i73 at that point. (or buy a second one)

Maybe a USB keyboard would work?

Thanks Andy.

I might as well just cram the 7i73 in the panel and use that instead of (or along with) the 7i84D.

I'm already planning to use a USB keyboard for data input, but I want an array of dedicated hardware buttons.  Cycle start & feed hold will be direct I/O, but time-insensitive functions will be on the matrix.

Yes, I have a touchscreen... but I can't stand touchscreens - need some tactile feedback.  And I've found that good old Cherry MX keyboard buttons are cheap, reliable, and feel great when you put heavy springs in them.  3D printers make it easy(ish) to cook up a Cherry-compatible grid panel.

Basic concept below.  Haas-ish flavored fuctions.

A panel-mount USB keyboard will be mounted on a hinged swing-up thing attached to the bottom of this panel.  Most times the keyboard will be flat, but if I'm doing a fair amount of editing/typing I can angle it up for better ergonomics.