did anybody build an USB-keyboard to serial adapter?

StefanL38

Hello,

I know PS/2-keyboards and mice are still available and can be directly connected to the propeller
and there are drivers for it.

Anyway I would like to ask

did anybody build a USB-keyboard to serial adapter?
NOT directly to the propellerchip as I know that this is very difficult.
But by using any kind of additional hardware Atmel 90USB1287 FTDI-chips or what ever

I mean connect a PURE USB-keyboard (which has NO PS/2-protocol implemented) to this adapter
and the adapter is outputting serial string messages or is outputting on PS/2-protocol ?

best regards

Stefan

Post Edited (StefanL38) : 7/28/2009 4:36:39 PM GMT

Leon

It's difficult, because host mode is required on the USB interface. It could be done with a Vinculum chip, or a PIC or something like it with USB OTG.

Leon

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SamMishal

Stefan,

There are converter plugs that cost a few $ that convert a USB board to PS2

I did not open one of them so I do not know what is inside. However from the size and

looks of it, it seems to me just a matter of wiring.



These plugs convert the purely USB keyboard to a PS2 and work perfectly even on

PCs that predate the USB era and do not know anything about a USB (like Windows 95).

I have one and I use it with my antiquated PC running W95 and Even a sometimes with the

DOS 6.2 machine that I keep for the sake of running some REAL old programs.



The USB keyboard works perfectly with the plug converter....it is about an inch by two

by 1/4 inch thick with a female USB on one end and a PS2 on the other.



I bought it from CompUSA back when they were still a store.



Samuel

localroger

SamMishal, those wiring-only converters only work with keyboards whose electronics are PS/2 aware. They don't convert USB to PS/2, they depend on the keyboard doing a check and going into PS/2 mode (with the pins on its USB connector redefined so that they work as redirected by the PS/2 adapter).

There are also converters for converting PS/2 keyboard/mice to USB for people who have PS/2 peripherals and newer computers with USB ports only. But I've never seen a commercial device that goes the other way, adapting a pure USB keyboard or mouse that isn't PS/2 aware for PS/2 service. The market for such a thing would be extremely limited (mainly to industry) and it would probably be very expensive if anyone bothered to make it.

In DIY land you would need a controller capable of doing USB host mode and running the PS/2 interface at the same time.

RobotWorkshop

I believe you may be looking for an adapter like this:

http://www.microcenter.com/single_product_results.phtml?product_id=0280942

It is supposed to work with USB only keyboards and may have a bit more smarts inside than just mapping pins from one connector to another.

Robert

Post Edited (RobotWorkshop) : 7/28/2009 9:34:55 PM GMT

StefanL38

Hello Sam,

I think most keyboards do (still) support both protocols USB and PS/2. But how long will this be available ?

So this kind of plug-converter will only work with USB / PS/2-keyboards but not with pure USB-keyboards

best regards

Stefan

WBA Consulting

USB to PS2 adapters are a simple relayout of pins to a different connector. For a USB keyboard/mouse to work on a PS2 port, however, it must support the PS2 protocol. Usually the box or device will state "PS2 compatible" or "USB/PS2". Sometimes they even come with a USB-PS2 adapter. (the two PS2 compatible keyboards I have came with adapters).

More info:

USB to PS2 Pinout:
pinouts.ru/InputCables/usb_ps2_mouse_pinout.shtml

PS2 Protocol:
www.computer-engineering.org/index.php?title=PS/2_Mouse/Keyboard_Protocol

There are numerous active devices on the market that utilize only PS2 (think dumb terminals, thin clients, machinery, etc) so PS2 mice and keyboards have a long way to go before they are end of life.

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Andrew Williams
WBA Consulting
IT / Web / PCB / Audio

Marka32

Is there a particular reason for this? What are you trying to do? Is there a particular keyboard that you are trying to convert? There are ways to do it, but I wonder if maybe just chopping off the USB hardware would make it easier. Or, buying a bare keyboard (which will likely have much better quality than a Pee-Cee keyboard) and wiring it for serial output. I haven't checked the catalogs lately for the chips, but I'm sure there are still keyboard chips available. Or, use an old PC/XT keyboard, and convert the scan codes. Or use just the controller.