gbadev.org forum archive

ampz wrote:

Keyboard support for GBA is easy!
alt 1: Try my ericsson chatboard hack, it's really cheap and simple.
alt 2: Connect any standard keyboard to the GBA comm port. PS/2 keyboards use 5V, GBA use 3.3V, but that's the only difference, the protocol is compatible.

That 2nd option intriged me :).

I've got loads of PS2 keyboards here, I wouldn't mind breaking some of them in order to make it work on the GBA!

How would one connect the pins in order to make it work?

Also, could it be possible to connect a CAT5 cable to the GBA?
Would be nice to hook it up to a router/hub :).
I know a CAT5 cable has 8 pins, but maybe you don't actually need some...

Forget ethernet. You don't even kow what you're talking about.

There is more than just hooking a PS/2 keyboard up to the GBA, there is, as I said, issues of voltage conversion, and you have to write a driver.
If you know how to do it, then do it, if you don't, then there is no way I can teach you all you need to know about electronics and serial communication protocols in order to do it.

With a little simple knowledge (and a ton of money) all things are possible. The keyboard would be very easy because it's a simple little async serial protocall, all you'd need to do is level conversion (should be quite easy if you only have unidirectional communication).

As for ethernet, you'd need some sort of ethernet chip to controll things (one is at http://www.embeddedethernet.com/). You'd also have to do level conversion. The big trick here would be that (at least in the example link given above) is that it uses an 8 bit interface. So you'd either have to use shift registers to convert to/from serial, or you'd have to have a microcontroller do everything for you and act like a simple serial device to the GBA.

But as for directly connection something to the GBA, you can do it, but you'll probably need a new GBA.
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--Michael

mbcook: Keyboards use a synchronous protocol, not a async. protocol.
Aside from voltage conversion of the signals you also have to generate 5V power to the keyboard.

There are no voltage conversion issues involved with interfacing a GBA to a ethernet controller.

I don't have time to do this, but building an ethernet interface for the GBA would actually be *VERY EASY* using the right tools!

http://www.lantronix.com/products/eds/xport/index.html

The above linked product is essentially a 3.3v low power serial device server with space for a user application. It supports 10/100 operation and is the size of a female ethernet connector. Depending on power requirements, it (99% certain)could be powered directly off of the link port. The "user" application could be used to interface to the special coms needs of the GBA link port and protocols, or could be accessed using a special API to allow an application to do device configuration or talk to the network directly. TCP/IP is entirely offloaded to the device server and configuration can even be done via an internal webserver, so there need not be any protocol intelligence on the part of the application.

I can see two basic applications for this:

1) Emulation of the link cable to allow for LAN/Internet gaming between even commercial games (latency would probably be a big big issue, though)

2) Network access by homebrew software

How about a serial mouse - wot voltage do they work on?
All you would have to do on the software side is peek at the serial registers and convert the data into usable info.

:) GBA mouse - Doom would be easier!
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gbadev.org forum archive

Hardware > Keyboard, CAT5, bla bla bla.. just some thoughts

#1504 - NEiM0D - Sun Jan 19, 2003 5:41 pm

#1520 - ampz - Sun Jan 19, 2003 8:43 pm

#3095 - mbcook - Tue Feb 18, 2003 5:05 am

#3104 - ampz - Tue Feb 18, 2003 8:23 am

#4803 - GoRK - Thu Apr 10, 2003 6:47 am

#11844 - www-fmsoftware-info - Tue Oct 21, 2003 1:11 pm