Hi all,
guess it's time now to present my little Keyboard Adapter to the public.
What it does is - take a PS2 or AT Keyboard and convert the keycodes to something compatible with
a DEC LK402 / 201 / other(?) Keyboard. I am using it to interfere with a VT320 terminal.
The controller is a PIC18f2520 that i had laying around. If you take another, you have to adjust the baud
rate and the internal speed settings.
The max232 can be used by datasheet specification for the capacitors and connects the terminal
rs232 data to the ttl level on the controller
The LM340 is just any 5V voltage regulator
R1 and R2 are just for safety. They can be 100ohms
RB0 on the controller is the input for the Clock Line of the PS2 Keyboard,
RC1 is the input for the PS2 data.
The ICSP header is for in-circuit programming and debugging purposes.
The source-code is a Microchip MPLAB 8.8 Project written in C18. It is somehow hacked together.
NO real initialization takes place when the terminal requests it. We just fake some ACK messages.
If you have another terminal device you may have to tweak my *cough* ack-fake-loop to get the desired results....
In general there is NO communication between the host and keyboard, AKA no keyboard LEDs.
Sometimes the SHIFT Key gets stuck. Thank you IBM for your completely insane AT keyboard mappings. If you
are stuck just press shift again. On the other side this it not too bad since capslock is not implemented either
What works are (mostly) all characters, escaping with ctrl works. F-Keys work, . Arrow keys work. Implementing new scancodes is
not too hard. Just look up the AT Keyboard scancode and enter your desired output keycode in the sourcecode definition array.
Feel free to improve my source. For me it is working good enough to install and use a OS.
Have fun
http://bigalpha.ath.cx/schaltplan.png
View attachment vtadap.zip
guess it's time now to present my little Keyboard Adapter to the public.
What it does is - take a PS2 or AT Keyboard and convert the keycodes to something compatible with
a DEC LK402 / 201 / other(?) Keyboard. I am using it to interfere with a VT320 terminal.
The controller is a PIC18f2520 that i had laying around. If you take another, you have to adjust the baud
rate and the internal speed settings.
The max232 can be used by datasheet specification for the capacitors and connects the terminal
rs232 data to the ttl level on the controller
The LM340 is just any 5V voltage regulator
R1 and R2 are just for safety. They can be 100ohms
RB0 on the controller is the input for the Clock Line of the PS2 Keyboard,
RC1 is the input for the PS2 data.
The ICSP header is for in-circuit programming and debugging purposes.
The source-code is a Microchip MPLAB 8.8 Project written in C18. It is somehow hacked together.
NO real initialization takes place when the terminal requests it. We just fake some ACK messages.
If you have another terminal device you may have to tweak my *cough* ack-fake-loop to get the desired results....
In general there is NO communication between the host and keyboard, AKA no keyboard LEDs.
Sometimes the SHIFT Key gets stuck. Thank you IBM for your completely insane AT keyboard mappings. If you
are stuck just press shift again. On the other side this it not too bad since capslock is not implemented either
What works are (mostly) all characters, escaping with ctrl works. F-Keys work, . Arrow keys work. Implementing new scancodes is
not too hard. Just look up the AT Keyboard scancode and enter your desired output keycode in the sourcecode definition array.
Feel free to improve my source. For me it is working good enough to install and use a OS.
Have fun
http://bigalpha.ath.cx/schaltplan.png
View attachment vtadap.zip
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