FTG Serial Light Pen
¬

¬	Pointing Devices

Overview

The FTG serial light pen device driver provides support for an FTG Light Pen attached via an FTG PXL-780 serial interface.  

An FTG light pen may be used in conjunction with a mouse or other pointing device.  You can keep both devices active, allowing you to choose which pointing device is more useful for a given task.

Using the Light Pen over Black regions

The light pen must be able to detect light from the screen in order to know where to move the cursor.  This presents a problem when using the light pen over large black areas on the screen.  While this is not generally a problem with OPENSTEP for Mach's user interface, you should be careful to avoid setting the background to a very dark color.

You can attach an FTG Blue Flood Unit to the PXL-780.  The blue flood unit will give the screen a blue cast if the light pen is in use over a dark area, allowing it to detect light and move the cursor correctly.

Installing and Configuring an FTG Light Pen

First, connect the PXL-780 to the serial port and monitor as described in the FTG PXL-780 User Manual.  Second, use Configure.app to configure the FTG serial light pen device driver.  

The FTG serial light pen driver must be used in conjunction with the Serial Port driver.  When configuring the Light Pen driver, you will notice a box titled "Serial Port #" that contains a number.  This number tells the Light Pen driver which Serial Port instance to use.  If only one instance of the Serial Port driver is configured, then the number in the box should be 1.  

Note:	The FTG serial light pen device driver is not compatible with the Serial Ports (v4.00) device driver that shipped on the OPENSTEP for Mach 4.0 CD-ROM.  You must use version 4.00 or later of the Serial Port device driver.

After setting the Serial Port number, save the configuration and quit Configure.  Restart the computer.  Log in as root and proceed to the Calibration process.

Calibrating the FTG Light Pen driver

You must calibrate the FTG serial light pen driver the first time it is installed and any time a new display mode is selected.  Also, you can re-calibrate the light pen driver any time to improve cursor tracking.

Run Configure.app and select the FTG light pen driver.  If the light pen driver successfully registered at boot time, the Calibrate button will be enabled.  Click the Calibrate button and follow the instructions presented.  After calibrating, you should save the configuration.

Setting the Response control

After completing calibration, you may wish to change the value of the Response field.  This controls the number of consecutive samples the driver averages to control the cursor location.  The higher the number, the slower and smoother the cursor motion.  The lower the number, the faster and more responsive the cursor is.  Larger numbers will help make the pen less jittery over large black regions.

After setting the Response control, save the configuration.

¬
	
See also

·	The topics in Configure's on-line help for the Serial Port device driver.  

·	"Add a Device" in Configure's on-line help.

·	See NeXTAnswer 1824 for general information on installing and configuring device drivers.