Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
Product codes
ATSAMD21-XPRO
795
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
31.8.4.4 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.
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: VARIABLE
These bits define the VARIABLE field of a received extended token.These bits are updated when the USB has
answered by an handshake token ACK to a LPM transaction. 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 read as described below.
These bits define the VARIABLE field of a received extended token.These bits are updated when the USB has
answered by an handshake token ACK to a LPM transaction. 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 read as described below.
Table 31-17. VARIABLE bit fields for LPM application
(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".
(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 Man-
agement Addendum" and "Table X-X1 in Errata for ECN USB 2.0 Link Power Management.
USB 2.0 Link Power Management Addendum".
(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 Man-
agement Addendum" and "Table X-X1 in Errata for ECN USB 2.0 Link Power Management.
z
Bits 3:0 – SUBPID: SUBPID
These bits define the SUBPID field of a received extended token.These bits are updated when the USB has
answered by an handshake token ACK to a LPM transaction. See Section 2.1.1 Protocol Extension Token in the
reference document “ENGINEERING CHANGE NOTICE, USB 2.0 Link Power Management Addendum”.
These bits define the SUBPID field of a received extended token.These bits are updated when the USB has
answered by an handshake token ACK to a LPM transaction. See Section 2.1.1 Protocol Extension Token in the
reference document “ENGINEERING CHANGE NOTICE, USB 2.0 Link Power Management Addendum”.
Bit
15
14
13
12
11
10
9
8
+1
VARIABLE[10:4]
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
X
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
+0
VARIABLE[3:0]
SUBPID[3:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
X
X
X
X
X
X
X
X
VARIABLES
Description
VARIABLE[3:0]
bLinkState (1)
VARIABLE[7:4]
BESL (2)
VARIABLE[8]
bRemoteWake (1)
VARIABLE[10:9]
Reserved