Interface a USB computer keyboard.

[Frankontheinterweb]

Hello,
Would anyone know how i could get the data of the keystrokes from the keyboard.

It's a USB connection and i can't find anywhere online that tells me how to get say ASCII codes from the usb keyboard.

What i would like to do it be able to get the data and be able to see bit by bit the ASCII code.

Could anyone give me any hints or suggestions on where to go from here?

Thanks

 

[Raven Luni]

Have a read at these:

http://www.usb.org/developers/docs/

 

[Harald Kapp]

Hello Frank,
a USB keyboard does not send ASCII codes directly to the PC. It relies on the so called HID (human interface device) protocol (http://en.wikipedia.org/wiki/Human_interface_device). So you will need a USB stack and HID driver to access the keyboard.

For your purposes a serial keyboard (PS2) would be more appropriate. This you can interface to a UART. See e.g. here http://www.computer-engineering.org/ps2keyboard/ for more details.

Regards,
Harald

 

[Raven Luni]

If youre using simple bit banging it shouldnt matter - as long as youre following the protocols correctly.

 

[Harald Kapp]

Right.
The tricky part is following the protocol.
Personally I think this is easier using a UART protocol than a USB HID protocol.
But then again, I'm only a hardware guy.

Harald

 

[Raven Luni]

Probably right. I'm only a software guy

 

[Frankontheinterweb]

Right thanks guys,
I did look into ps/2 keyboards, but as i have thrown out my old keyboard i would have to buy another (this is why i wanted to use usb). Though there does seem to be alot more documentation on the ps/2 keyboard interfacing.

The USB protocol seems amazingly complicated. It there anywhere on the web that gives info on someone who has done something similar? Rather than reading long protocol specifications.

Thanks for the help. If worst comes to the worst i will buy a ps/2 keyboard, as i saw some pretty good documentation on that.

Thanks

 

[Raven Luni]

A keyboard will never use anything above 1.1 so that narrows the list a bit. I dont know of anyone personally whos working with it but I plan to at some point with my z80 projects (that doesnt help you right now though). You might want to try the linux community.

 

[Raven Luni]

Then again theres probably an arduino module or something similar you could get. I wouldnt know much about that stuff though (I'm allergic to over-simplification )

 

[Harald Kapp]

You know that there are USB-to-PS/2 adapters? Starting at 1€ on the internet.

Harald