28EX II 3000SP Controller Reference Guide

Format Tablet

Syntax:

<SOH>FT<CR>

 

 

 

 

 

 

 

 

Description:

Outputs the X/Y touch coordinate data in a 5-byte packet. The packet

 

 

includes 1 status byte and 4 bytes of binary X/Y coordinate data. The

 

 

protocol also establishes the X and Y coordinate output as 14 binary bits

 

providing a range of 0 to 16,383.

 

 

 

 

 

 

 

The low order bits (X3 – X0 and Y3 – Y0) are not significant in a 1024 by

 

1024 touch screen because data can fluctuate with each touch, and therefore

 

may not be completely accurate.

 

 

 

 

 

 

 

To use Format Tablet, the controller and host system must be in an 8-bit

 

data communication mode. The Format Tablet command returns a negative

 

response if the controller is in 7-bit format.

 

 

 

 

Response:

<SOH>0<CR> Positive response

 

 

 

 

 

 

After the controller is in Format Tablet mode, touching the screen causes

 

the controller to return a response in the following format:

 

 

 

SXxYy

 

 

 

 

 

 

 

 

 

 

S

=

Status byte, first byte of data. Refer to Table 8.

 

 

 

 

Xx

=

X (horizontal) coordinate data; second and third bytes of data.

 

Yy

=

Y (vertical) coordinate data; fourth and fifth bytes of data.

 

 

Table 8 Data Sequence

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MSB*

 

 

Bits

 

 

 

LSB*

 

Data Sequence

7

6

5

4

3

2

1

0

 

S

 

- Byte 1

1

S6

S5

S4

S3

S2

S1

S0

 

X

 

- Byte 2

0

X6

X5

X4

X3

X2

X1

X0

 

x

 

- Byte 3

0

X13

X12

X11

X10

X9

X8

X7

 

Y

 

- Byte 4

0

Y6

Y5

Y4

Y3

Y2

Y1

Y0

 

y

 

- Byte 5

0

Y13

Y12

Y11

Y10

Y9

Y8

Y7

*MSB = Most Significant Bit, LSB = Least Significant Bit

Table 9 defines the status bits (Byte 1) for the Format Tablet data.

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