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The "SmartWye"™ PC USB Keyboard Encoders make it easy to convert switch or contact closures to standard USB keyboard codes for input to a PC's USB port. The USB keyboard encoders enumerate as a standard HID keyboard, and support USB bus suspend and remote wake-up. If enabled by the USB host, an input contact closure will generate a remote wake-up signal on the USB bus. The USB Encoder model USB-312 contains an on-board USB hub providing an input for an USB peripheral. If any device is connected to the hub, its current draw must not exceed 400 mA.
The encoder detects and debounces switch closures, generates appropriate key codes, and sends them to the PC. When the switch is opened, the encoder sends a code indicating that the key is open.
The USB Keyboard Encoder can generate one of four different USB keyboard code output configurations, selected by settings of jumpers JP3 and JP4. Jumpers MUST BE set prior to applying power to USB Keyboard Encoder for correct keyboard code configuration outputs. The USB codes generated are shown in the table below:
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USB-311/312 Matrix Key Codes, see Table 2 |
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USB-311/312 Function Key Codes, see Table 1, column -24F |
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USB-311/312 Numeric Key Codes, see Table 1, column -24N |
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USB-311/312 Alpha Key Codes, see Table 1, column -24A |
The keyboard code generated for a given switch closure is shown in the two tables (maps) below in terms of US keyboard key cap legends. J3 is the switch input connector to the USB PC keyboard encoder.
The first table, Table 1, shows three standard maps for the keyboard encoder models that accept up to 24 discrete contact closures to ground. The key code is generated when the J3 pin in the table is closed to the GND pin. The "A" (ALPHA) map generates mostly alphabetic keys, the "F" (FUNCTION) map generates functions keys, and the "N" (NUMERIC) map generates numeric keys.
Table 2 applies to matrix-connected switches, such as found on many membrane keypads. The matrix configuration of the keyboard encoder contains the complete Windows 104 keys of the standard PC keyboard with switches connected in an 8 by 13 matrix.
In order to assure proper operation of the "SmartWye", certain conditions should be observed in its application. The following is a list of these conditions:
ALL CONNECTIONS SHOULD BE MADE WITH THE PC POWER OFF!!
1. Set-up: You can connect the "SmartWye" USB Keyboard Encoder to the PC at any time (plug-and-play). You do not have to power-down the PC to make this connection. Use a standard USB Type A-B cable (may be purchased separately from Vetra) to connect the keyboard encoder to any convenient USB port on the PC. The USB Keyboard Encoder is powered from the PC via this cable. After plug-in, the Pc takes a short time to recognize (enumerate) the USB Keyboard Encoder; then the USB Keyboard Encoder is ready for operation. Jumpers (JP3 and JP4) must be set prior to applying power to the encoder board for correct keyboard code configuration. To set the encoder for a different key code output configuration, the encoder must be unplugged from the PC, jumpers reconfigured and than plug the encoder back into the PC.
2. Alternative host connection: Connection via the J1 connector location is provided if a connection other than USB Type A-B cable is required. Vetra does not manufacture an Interface cable for this connection. (See the pin out information at end of these instructions for connections to J1).
3. Hub Connection (USB-312 Encoders only): Connect an USB keyboard or any low or full-speed USB device to the built-in USB hub on the encoder at connector J6. The device can be connected at any time. The PC takes a short time to recognize (enumerate) the device, and then is ready for operation. The total current draw of the device connected to the hub must not exceed 400 mA.
4. Alternative Hub connection: Connection via the J2 connector location
is provided if a connection other than USB Type A connection is
required. Vetra does not manufacture an Interface cable for this
connection. (See the pin out information at end of these instructions
for connections to J2).
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The "Smart-Wye" USB Keyboard Encoders also support Num Lock, Caps Lock, and Scroll Lock status indicating LED's. By adding the J4 header, the "Smart-Wye" USB Keyboard Encoders can be configured to support keyboard indicator LED's. The encoders will source 2 mA on the folowing pins:
| J1-1 Vcc | J2-1 Vcc |
| J1-2 USB D- | J2-2 USB D- |
| J1-3 USB D+ | J2-3 USB D+ |
| J1-4 Not Used | J2-4 Not Used |
| J1-5 Shield | J2-5 Shield |
| J1-6 Gnd | J2-6 Gnd |
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275 Marcus Blvd. Ste-J, Hauppauge, NY 11788-2022 USA Toll Free 1-800-537-9296 Tel: 631-434-3185 Fax: 631-434-3516 e-mail: sales@vetra.com |