Read Parameter Request 16 - 3M Touch Screen Controller EX 111 Reference Manual

3M™ MicroTouch™ Controller EX USB Reference Guide

Read Parameter Request 16

This is a request to send the contents of a parameter via the control endpoint. This is a
one-time transfer of data. The request is used to access data in the controller.
This request provides a means for reading the configuration parameters. The request uses
parameter numbers to determine what data is being requested and where that data is
located.
Table 18. Read Parameter Request
Offset
0
1
2
4
6
The direction bit in bmRequestType has been set to 1 (device-to-host) to return the
contents of the requested parameter.
The byte bRequest is set to 16 to indicate that this is the Read Parameter request.
The wValue field is set to the number of the parameter being requested.
This request does not use the wIndex field. This field should be set to zero to ensure
future compatibility.
The wLength field is the number of bytes being sent by the device to the host. The data is
returned to the host in the format of the Parameter Data report, which has a 3-byte header,
so 3 must be added to the number of parameter bytes desired. The following table lists
the parameters currently supported and the appropriate settings for the request fields.
Table 19. Supported Parameters
Parameter
(wValue) wIndex
0 0
1 0
2 0
Field Size
bmRequestType 1
bRequest 1
wValue 2
wIndex 2
wLength 2
wLength
(bytes+3) Range
0 0
5 0 – 3
7 0 – 2
3M Touch Systems, Inc. Proprietary Information -- 29489v05
Value Description
11000000 Characteristics
16 Command number
0xXXXX Parameter number
0x0000 Not used
0xXXXX Length of Parameter Data report
Description
Reserved for future use
Sensor orientation - where the lower left
corner of the display maps to the sensor.
0000 – Upper right
0001 – Lower right
0002 – Upper left
0003 – Lower left (standard, not rotated)
32
-1 Controller serial number
27