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EX II Serial Controllers Reference Guide
3M Touch Systems Proprietary Information
S
= Status byte, first byte of data. Refer to Table 4.
Xx
= X (horizontal) coordinate data; second and third bytes of data
Yy
= Y (vertical) coordinate data; fourth and fifth bytes of data.
Table 4 Data Sequence
MSB*
Bits
LSB*
Data Sequence
7
6
5
4
3
2
1
0
S- Byte 1
1
S6
Reserved
X-
Byte
2
0 X3 X2 X1 X0 Reserved
x-
Byte
3
0 Xs**
X9 X8 X7 X6 X5 X4
Y-
Byte
4
0 Y3 Y2 Y1 Y0 Reserved
y-
Byte
5
0 Ys**
Y9 Y8 Y7 Y6 Y5 Y4
*
MSB = Most Significant Bit, LSB = Least Significant Bit
**
s = sign bit
Table 5 describes the meaning of the bits in the status byte (Byte 1).
Table 5 Calibrate Raw Status Bits
Bit
Description
Values
S0 – S5 Reserved
—
S6
Proximity (touch state) 1 = Touch screen is being touched (a touchdown or a continued touch).
0 = Touch screen 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.
S7
Packet synchronization Always 1.
Diagnostic Command
Syntax:
<SOH>
DX
<CR>
Description:
This command requests the controller to check for touch screen failures such as broken
corners, broken wires, etc.
Response: <SOH>
0
<CR> Positive
response.
<SOH>
1
<CR>
Command not supported.
<SOH>
2
<CR> Failure
detected.
