RM0402 Rev 6 1041/1163
RM0402 USB on-the-go full-speed (OTG_FS)
1122
29.15.35 OTG device status register (OTG_DSTS)
Address offset: 0x808
Reset value: 0x0000 0010
This register indicates the status of the core with respect to USB-related events. It must be
read on interrupts from the device all interrupts (OTG_DAINT) register.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Res. Res. Res. Res. Res. Res. Res. Res. DEVLNSTS[1:0] FNSOF[13:8]
rrrrrrrr
1514131211109876543210
FNSOF[7:0] Res. Res. Res. Res. EERR ENUMSPD[1:0]
SUSP
STS
rrrrrrrr rrrr
Bits 31:24 Reserved, must be kept at reset value.
Bits 23:22 DEVLNSTS[1:0]: Device line status
Indicates the current logic level USB data lines.
Bit [23]: Logic level of D+
Bit [22]: Logic level of D-
Bits 21:8 FNSOF[13:0]: Frame number of the received SOF
Bits 7:4 Reserved, must be kept at reset value.
Bit 3 EERR: Erratic error
The core sets this bit to report any erratic errors.
Due to erratic errors, the OTG_FS controller goes into suspended state and an interrupt is
generated to the application with Early suspend bit of the OTG_GINTSTS register (ESUSP
bit in OTG_GINTSTS). If the early suspend is asserted due to an erratic error, the application
can only perform a soft disconnect recover.
Bits 2:1 ENUMSPD[1:0]: Enumerated speed
Indicates the speed at which the OTG_FS controller has come up after speed detection
through a chirp sequence.
11: Full speed using embedded FS PHY
Others: reserved
Bit 0 SUSPSTS: Suspend status
In device mode, this bit is set as long as a suspend condition is detected on the USB. The
core enters the suspended state when there is no activity on the USB data lines for a period
of 3 ms. The core comes out of the suspend:
– When there is an activity on the USB data lines
– When the application writes to the remote wakeup signaling bit in the OTG_DCTL register
(RWUSIG bit in OTG_DCTL).
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