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22 USB 2.0 FS DEVICE CONTROLLER (USB, USBMISC)
SUSPEND state
NONJDETEN != 1
LineState != K || SE0
LineState == K
LineState == K
RESUME state
(1) DISABLE
The USB controller is placed into DISABLE state when the USBCTL.AUTONEGOEN bit = 0. To enable the
auto-negotiation function from this state, perform the procedure shown below.
1. Set the USBSIEINTE.RESETIE bit to 1.
2. Set the USBSIEINTE.SUSPENDIE bit to 1.
3. Set the USBMAININTE.SIEIE bit to 1.
4. Set the USBCTL.AUTONEGOEN bit to 1.
When the auto-negotiation function is enabled, the controller hardware automatically clears the USBCTL.BUS-
DETDIS bit to enable the event detection function. While the auto-negotiation function is enabled, never set the
USBCTL.BUSDETDIS bit.
(2) NORMAL
This is a state of waiting for Reset or Suspend detection. The state is determined to be Reset if SE0 of 2.5 µs
or more is detected, and it is determined to be Suspend if no activities are detected beyond 3 ms. Concurrently
with judgment as described above, the USBSIEINTF.RESETIF bit or the USBSIEINTF.SUSPENDIF bit is set
and a Reset detection or Suspend detection interrupt is generated. If the state is determined to be Suspend, the
USB controller enters IN_SUSPEND state.
22-14
AUTONEGOEN != 1
AUTONEGOEN == 1
BUSDETDIS = 0
DetectSeq = start
RESETIF == 0 and
SUSPENDIF == 0
NORMAL state
SUSPENDIF == 1
DetectSeq = stop
NONJDETEN = 1
IN_SUSPEND
NONJIF == 1
NONJDETEN == 0
LineState == SE0
CHK_EVENT
DetectReset
WAIT_SE0
LineState == SE0
Figure 22.5.7.1 Auto-Negotiator
Seiko Epson Corporation
AUTONEGOEN == 0
DISABLE
RESETIE = 1
SUSPENDIE = 1
NORMAL
RESETIF == 1
DetectSeq = stop
WAIT_SE0END
DetectSeq = start
(Enable Reset detection interrupt)
(Enable Suspend detection interrupt)
(Enable SIE interrupt)
(Enable auto-negotiation)
RESET state
LineState == SE0
LineState == J
S1C31W74 TECHNICAL MANUAL
(Rev. 1.1)
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