Document Number: 37078

www.vishay.com

Revision: 14-Jan-10

5

TIP-4735SEE-1

14" Infrared Touch Panel

Vishay Dale

Invert X (37)

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 standards or third party mechanical

packages which may have the touch panel rotated 180° 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 inverted Y data. The jumper

selected options may be over-ridden 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 sensing). 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 reporting enabled, the time is typically 25 s

to 30 s. If the application requires longer touch times, then

the time may be extended 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 command).

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

exceeded 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 process

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

reporting is not desired unless requested, so automatic

reporting 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.

HOST

TOUCH PANEL

ACTION

Send 22

Send 2B

Enables enter point mode

Request report

Send 48

No report is available

Send 2B

Request report

Send 42, 1D, 12

A stylus entered the touch

panel. The coordinates are

X29, and Y18 (decimal)

(See touch point format)

Send 2B

Request report

Send 48

No report is available