3M M2256PW manual Touch Data Format, Bit Description, Data Sequence Bits

383M™ Multi-touch Display M2256PW User Guide

AD Indicates the PX series of controllers

Ffff = Four ASCII characters that indicate the features supported by the controller.

****Indicates no additional features configured

Ss	= Two ASCII characters that provide status information about the
	controller hardware. The two characters represent one byte. Each
	character is in the range 0 to 9 and A to F.
	Table 2 defines the meaning of each bit in the status byte. Each bit
	can be set to 1 or 0, where 1 = an error and 0 = no error. So a
	response of:

00 = No diagnostic errors (normal response)

The PX running with no errors returns the following string:

<SOH> AD****00 <CR>

The format includes two bitmapped ASCII hex status bytes. A “00” indicates no errors.

Table 19 Bit Meanings in Status Byte

Bit	Description	Notes
0	Not used
1	ROM_ERROR	Code area checksum error
2	PWM Error	Touch screen not connected or potential problem.
3	NOV_ERROR	Parameter Block1 checksum error
4	HDW_ERROR	Problem with ADCs
5	Not used
6	Not used
7	Not used

Touch Data Format

The format is a six byte packet that includes one status byte, four bytes of binary X,Y position data and a touch ID. The X,Y coordinates are 14 bits, providing a range of 0 to

16,383. The data is sent in the following format:

Table 20 Touch Data Format Settings

Data Sequence	Bits
	7	6	5	4	3	2	1	0
Status - Byte 1	1	P1	0	0	0	0	0	0
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

3M Touch Systems, Inc. Proprietary Information – 37531 Rev D