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M451
May. 4, 2018
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6.19.7 Register Description
OTG Control Register (OTG_CTL)
Register
Offset
R/W
Description
Reset Value
OTG_CTL
0x00
R/W
OTG Control Register
0x0000_0000
31
30
29
28
27
26
25
24
Reserved
23
22
21
20
19
18
17
16
Reserved
15
14
13
12
11
10
9
8
Reserved
7
6
5
4
3
2
1
0
Reserved
WKEN
OTGEN
Reserved
HNPREQEN
BUSREQ
VBUSDROP
Bits
Description
[31:6]
Reserved
Reserved.
[5]
WKEN
OTG ID Pin Wake-up Enable Bit
0 = OTG ID pin status change wake-up function Disabled.
1 = OTG ID pin status change wake-up function Enabled.
[4]
OTGEN
OTG Function Enable Bit
User needs to set this bit to enable OTG function while USB frame configured as OTG
device. When USB frame not configured as OTG device, this bit is must be low.
0= OTG function Disabled.
1 = OTG function Enabled.
[3]
Reserved
Reserved.
[2]
HNPREQEN
OTG HNP Request Enable Bit
When USB frame as A-device, set this bit when A-device allows to process HNP
protocol
—A-device changes role from Host to Peripheral. This bit will be cleared when
OTG state changes from a_suspend to a_peripheral or goes back to a_idle state.
When USB frame as B-device, set this bit after the OTG A-device successfully sends a
SetFeature (b_hnp_enable) command to the OTG B-device to start role change
—B-
device changes role from Peripheral to Host. This bit will be cleared when OTG state
changes from b_peripheral to b_wait_acon or goes back to b_idle state.
0 = HNP request Disabled.
1 = HNP request Enabled (A-device can change role from Host to Peripheral or B-device
can change role from Peripheral to Host).
Note:
Refer to OTG specification to get a_suspend, a_peripheral, a_idle and b_idle state.
[1]
BUSREQ
OTG Bus Request
If OTG A-device wants to do data transfers via USB bus, setting this bit will drive VBUS
high to detect USB device connection. If user w
on’t use the bus any more, clearing this
bit will drop VBUS to save power. This bit will be cleared when A-device goes to
A_wait_vfall state. This bit will be also cleared if VBUSDROP (OTG_CTL[0]) bit is set or
IDSTS (OTG_STATUS[1]) changed.
If user of an OTG-B Device wants to request VBUS, setting this bit will run SRP protocol.
This bit will be cleared if SRP failure (OTG A-device does not provide VBUS after B-