3M Touch Screen Controller RX141, Справочное руководство

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3M™ MicroTouch™ Controller RX141 Reference Guide 27
3M Touch Systems, Inc. Proprietary Information
Response
If the command cannot be processed, the device stalls endpoint 0. The command cannot
be processed if the memory area is not valid. It cannot be processed if the request is
attempting to access data that is outside the specified memory area. This may happen if
the index is too large or too much data has been requested.
The host can send a status request, as long as the endpoint is not stalled, to determine if
this request was executed properly.
Get Feature – Get Controller Number
This command is used to get a controller number for application use. The controller does
not use this value. This process is useful for identifying individual controllers in a
multiple controller system.
Due to HID functionality, retrieving data from the controller involves two steps.
1. Requesting the controller number parameter
2. Retrieving the controller number value
Table 26. Get Controller Number Parameter Request
Offset Field Size Value Description
0 bmRequestType 1 0x21 Device to host
1 bRequest 1 0x09 Set Report
2 wValue 2 0x0303 03 = Feature
03 = Feature Report ID
4 wIndex 2 0 Always 0
6 wLength 2 0 Always 8
Table 27. Data Stage
Offset Field Size Value Description
0 bReport ID 1 0x03 Feature Report ID
1 bmReport
Subtype
1 0x02 Indicates a set param index
2 bArea 1 0 Memory Area (always 0=Ctrl
EEPROM )
3 Not used 1 0 Not used
4 bSubArea 1 0x05 Block number
5 bIndex 1 0x00 Index into block.
6 bDataLength 1 0x04 Number of valid data bytes for
xfer (always padded to 64)
7 Not used 1 0 Not used