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TIP-4131SCE-1

Vishay Dale

Document Number: 37070

Revision 28-Jun-01

COMMAND/RESPONSE DESCRIPTION (Contd.)

Sound beeper, tt = duration (00 to FF) (2Ftt)

This command sends a logic 0 (active state) to pin 2 of J4.

The duration of the beep can be controlled in 10 msec incre-

ments from 0 msec (00) to 2.55 sec (FF). Note - 2C may not

be used as an argument as it will cause a reset.

*Normal X

(36)

Invert X

(37)

*Normal Y

(38)

Invert Y

(39)

The standard configuration for the touch panel places the XY

origin at the lower left corner, consistent with the Cartesian

coordinate system. Upon issuing the INVERT Y command,

the origin becomes the upper left corner, consistent with the

video industry standard. These commands allow the user to

move the origin to any corner to accomodate different stan-

dards or third party mechanical packages which may have the

touch panel rotated 180 degrees on the display. To cancel an

INVERT X or INVERT Y command, a NORMAL X or NORMAL

Y command must be executed. These commands may also

be implemented with jumpers. Placing a shunt on NOR X

causes X data to be normal (default), and removing the shunt

causes inverted X data. Similarly, placing a shunt on NOR Y

causes Y data to be normal (default), or removal causes in-

verted Y data. The jumper selected options may be over-rid-

den with the software commands.

Failed beam time-out (3A t)

If any IR beam is broken for an extended time due to blockage

of the beam or failed optical components, the touch panel will

ignore that beam after a predetermined number of scans. (This

is to prevent failed beams from interfering with touch sens-

ing). The actual failed beam detection time depends on the

modes of operation and the size of the touch matrix. When

using the CONTINUOUS mode with AUTOMATIC REPORT-

ING enabled, the time is typically 25-30 seconds. If the appli-

cation requires longer touch times, then the time may be ex-

tended using the FAILED BEAM TIME-OUT command. The

command accepts arguments from 1 to F.

Request failed beam report (28)

This command returns the address of any infrared diode/

phototransistor pair that are blocked (as when a stylus is in

the panel) or have several failed scans. (The time period can

be extended by using the FAILED BEAM TIME-OUT com-

mand). The report uses the following format:

47 = start of failed beam report

aa-nn = physical address of failed LED/Phototransistor pair.

FF = end of report

Reset touch panel (2C)

After issuing the RESET command, the touch panel is returned

to its power up condition and all operating modes are returned

to their default state and the buffer cleared.

Request software revision number (30)

Request touch matrix size (33)

Request model number (35)

These commands are provided for configuration control and

diagnostic purposes.

RS-232 framing or overrun error (45)

An RS-232 error indicates communication problems.

Buffer overflow error (4F)

Buffer overflow occurs when the input command buffer is ex-

ceeded due to lack of handshaking.

INITIALIZATION

Initialization is performed by the host computer and must be

done each time the touch panel is powered up or the RESET

TOUCH PANEL command is issued. The initialization pro-

cess requires setting the desired coordinate reporting modes,

enabling or disabling AUTOMATIC REPORTING, and enabling

or disabling the touch panel. Default settings are shown in the

COMMANDS table.

When touch coordinate information is required by the host

computer, the touch panel must be enabled. The flow of touch

coordinates from the touch panel to the host computer can be

controlled by enabling or disabling AUTOMATIC REPORTING.

With AUTOMATIC REPORTING enabled, coordinate reports

are sent to the host as soon as they become available. If the

host computer is performing a task which does not require

touch coordinate information, AUTOMATIC REPORTING may

be disabled.

INITIALIZATION/OPERATION-EXAMPLE

In the following example the touch panel is initialized to report

coordinates only when a stylus is entered into the touch panel.

The touch panel is enabled by default, and coordinate report-

ing is not desired unless requested, so AUTOMATIC REPORT-

ING is left disabled by default.

As a result the touch panel must be continuously polled with

REQUEST ONE COORDINATE REPORT (2B) to determine if

an enter point coordinate report is available. When a report is

available, it will be sent to the host. If no report is available,

the touch panel will send code 48 (hex) to the host.