Re: remote unit for emc

["D.F.S." <dfs-at-xmission.com>]

> 
> 
> Hi!
> I want to design a remote to be used with emc. I dont
> need it to be wireless.I was thinking to use another
> keyboard connected in parallel or with some (AND/OR
> logic) with the primary keyboard. I am thinking to
> modify and use the pc-keyboard circuit with push
> buttons for jogging, homing etc for this remote.
> 
> Please suggest what may be the best method to
> accomplish this task?
> or has anyone already done that?

The keyboards run a serial protocol.
a simple electrical AND/Parallel approach won't work.
A logical OR where the 'keyboards' are swapped completely MAY.
As to hacking a keyboard it straightforward but likely to look like a 
rube goldberg contraption when you are done.
Compact and 'Crud Tight' would be important in this application IMHO.

There are several versions of the Atmel AVR uController chips that should
work well. 
There are appnotes and sample code and projects to act as keyboards.

You can get a simple part in single qty that could do this for $1.75.

Now for $6.00 you can get a part with 8 10bit analog inputs, serial ports
512 bytes of non-volatile memory 1K of RAM and 16K Program memory.

That one part could everything up to and including the whole user interface.

Having a microcontroller allows lots of other options like keyboard macros
e.g. button 1 sends 4 key press codes necessary to make the machine do X.

Marc