Data Sheet

839
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181G–SAM-D21_Datasheet–09/2015
31.8.7.4 Extended Register
Name:
EXTREG
Offset: 0x08
Reset: 0xxxxxxxx
Property: NA
z Bits 15 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z Bits 14:4 – VARIABLE: Extended variable
These bits define the VARIABLE field sent with extended token. See “Section 2.1.1 Protocol Extension Token in
the reference document ENGINEERING CHANGE NOTICE, USB 2.0 Link Power Management Addendum.”
To support the USB2.0 Link Power Management addition the VARIABLE field should be set as described below.
Table 31-29. VARIABLE bit fields for LPM application
z Bits 3:0 – SUBPID: SUBPID
These bits define the SUBPID field sent with extended token. See “Section 2.1.1 Protocol Extension Token in the
reference document ENGINEERING CHANGE NOTICE, USB 2.0 Link Power Management Addendum”.
To support the USB2.0 Link Power Management addition the SUBPID field should be set as described in “Table
2.2 SubPID Types in the reference document ENGINEERING CHANGE NOTICE, USB 2.0 Link Power Manage-
ment Addendum”.
Bit151413121110 9 8
+1
VARIABLE[10:4]
Access R R/W R/W R/W R/W R/W R/W R/W
ResetXXXXXXXX
Bit76543210
+0
VARIABLE[3:0] SUBPID[3:0]
Access R/W R/W R/W R/W R/W R/W R/W R/W
ResetXXXXXXXX
VARIABLE Description
VARIABLE[3:0] bLinkState
(1)
1. for a definition of LPM Token bRemoteWake and bLinkState fields, refer to "Table 2-3 in the reference document ENGINEERING CHANGE NOTICE, USB
2.0 Link Power Management Addendum"
VARIABLE[7:4] BESL (See LPM ECN)
(2)
2. for a definition of LPM Token BESL field, refer to "Table 2-3 in the reference document ENGINEERING CHANGE NOTICE, USB 2.0 Link Power
Management Addendum" and "Table X-X1 in Errata for ECN USB 2.0 Link Power Management.
VARIABLE[8] bRemoteWake (1)
VARIABLE[10:9] Reserved