Format Tablet - 3M Touch Screen Controller SX112 Reference Manual

3M™ MicroTouch™ Controller SX112 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 sensor
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.
With the controller in Format Tablet mode, touching the sensor causes the controller to
return a response in the following format:
SXxYy
= Status byte, first byte of data. Refer to Table 10.
S
Xx = X (horizontal) coordinate data; second and third bytes of data.
Yy = Y (vertical) coordinate data; fourth and fifth bytes of data.
Table 10 Data Sequence
Data Sequence 7
S
X
x
Y
y
*MSB = Most Significant Bit, LSB = Least Significant Bit
Table 11 defines the status bits (Byte 1) for the Format Tablet data.
Table 11 Format Tablet Status Bits
Bit Description
S0 – S5 Reserved
S6 Proximity (touch state)
S7 Packet synchronization
MSB*
6
Byte 1 1 S6
Byte 2 0 X6
Byte 3 0 X13
Byte 4 0 Y6
Byte 5 0 Y13
Values
—
1 = Sensor is being touched (a touchdown or a continued touch).
0 = Sensor is not being touched (a touch liftoff or inactive).
When the proximity bit changes from 1 to 0 (touch liftoff), the
controller outputs one final set of X/Y coordinate data with the bit
equal to 0 and the X/Y coordinate data equal to the last touch point.
Always 1.
3M Touch Systems, Inc. Proprietary Information
Bits
5 4 3
S5 S4 S3
X5 X4 X3
X12 X11 X10
Y5 Y4 Y3
Y12 Y11 Y10
LSB*
2 1 0
S2 S1 S0
X2 X1 X0
X9 X8 X7
Y2 Y1 Y0
Y9 Y8 Y7
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