USB Keyboard Shield for VT100

Rev. 2.1

About

The USB Keyboard Shield for VT100 connects a standard USB keyboard to Digital's VT100 terminal.

Features:

All keys on the VT100 keyboard are mapped to the USB keyboard keys.
VT100 keyboard LEDs and bell are implemented on the shield.

The Gerber file, BOM, schematic and Arduino sketch for the shield are included in the project folder. The steps to assemble, program and connect the shield are described in this document.

This shield requires the USB Host Shield by Circuits@Home.

Please use the information in this project at your own risk. No warranty or guarantee is provided.

Required Components

USB Keyboard Shield for VT100 (the shield from this project)
USB Host Shield by Circuits@Home, the "full-sized board"
Arduino Uno
Keyboard cable for VT100 (see "Keyboard Cable" below)
USB Keyboard

Required Steps

Assemble the shield
Make a keyboard cable
Program the Arduino
Connect the shields and cables

The details of each step are described in the next few sections.

Shield Assembly

The USB Keyboard Shield for VT100 can be assembled using the following info:

PCB Gerber File: usbkbd_vt100_2_1_gerber.zip
Schematic: usbkbd_vt100_sch.pdf
BOM: usbkbd_vt100_BOM_2_1.pdf

Keyboard Cable

To make the keyboard cable, connect these components:

1/4 inch stereo plug/cable
5-pin header connector

PIN CONNECTION

Pin	Plug	Value
1*	-	(spk+)*
2*	-	(spk-)*
3	Tip	+12V
4	Sleeve	GND
5	Ring	Signal

* optional

The pin connector is attached to J1 header on the USB Keyboard shield for VT100. The stereo plug is connected to the keyboard port on VT100 terminal.

Programming Arduino Uno

It is recommended to program the Arduino Uno before attaching the shields.

Install USB Host Shield Library 2.0 and Timer1 Library into Arduino IDE.
Clone or download this project.
Open the sketch usbkeyboardvt100/usbkeyboardvt100.ino in Arduino IDE, and program the Arduino Uno.

Configuration Options

There are two options in usbkeyboardvt100.ino:

// SWAPCAPS: If defined, LeftCtrl and CapsLock are swapped on USB Keyboard.
#define SWAPCAPS

// SWAPLFBAR: If defined, swap LineFeed and '|\' key codes for VT100.
//#define SWAPLFBAR

Comment out/uncomment the #define lines as needed.

Connecting the Shields and Cables

Connect the USB keyboard to the USB connector on the USB Host Shield.
Connect the keyboard cable for VT100 to J1 header on the USB Keyboard Shield for VT100.
Connect the keyboard cable to the keyboard port on VT100 terminal.
Stack and connect the Arduino Uno, the USB Host Shield, and the USB Keyboard Shield for VT100, in this order, from the bottom to the top.
No external power supply is needed. The power is supplied by the VT100 terminal via the keyboard cable.

Key Mapping

Some hard-to-guess keys:

VT100 Key	USB Keyboard Key
SET UP	F1, SysRq
CTRL	Caps Lock
CAPS LOCK	Left Ctrl
BREAK	Break
LINE FEED	End
NO SCROLL	Scroll Lock
PF1	Num Lock, F9
PF2	(pad) /, F10
PF3	(pad) *, F11
PF4	Page Up, F12
(pad) ,	(pad) +

The key mapping is defined in usb_key_tbl[] in usbkeyboardvt100.h. Also see "Configuration Options" above.

Reference Configuration

The following configuration was used during development of the shield:

USB Host Shield 2.0
Arduino Uno R3
VT100-WA
USB Keyboards: HP K1500 and Logitech K310

Known Issues

When the VT100 terminal is turned off, a short beep may be generated on the shield.
Keyboard connected via a USB hub is not supported.

GPL

The code is released under the GNU General Public License.

VaxCavalera/usbkbdshield_vt100