28 USB FUNCTION CONTROLLER (USB)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
28-13
time
DetectSuspend
Snooze
DisBusDetect
LineState[1:0]
USBDP/USBDM
Internal clock
T
0
T
1
T
2
T
3
T
4
T
5
Last Activity
"J" State
"J" State
Fully meet USB2.0 required frequency
5.1.9 Suspend Timing (FS mode)
Figure 28.
Reset detection
When the USB_Control.DisBusDetect bit is set to 0, the macro hardware automatically performs the fol-
lowing Reset detection sequence.
(1) The internal timer checks that it has continued to detect “SE0” in USB_Status.LineState[1:0] for 2.5 µs
or longer (T
1
).
(2) At T
2
, if “SE0” is detected in USB_Status.LineState[1:0], the macro sets the SIE_IntStat.DetectReset
bit.
(3) If the SIE_IntEnb.EnDetectReset and MainIntEnb.EnSIE_IntStat bits are set, the macro asserts the
#INT signal.
If the SIE_IntStat.DetectReset bit is set, on the firmware that controls this macro, set the USB_Control.Dis-
BusDetect bit to 1.
time
DetectReset
DisBusDetect
LineState[1:0]
USBDP/USBDM
T
-1
T
0
T
1
T
2
Last Activity
"J" State
"J" State
Driven SE0
SE0
5.1.10 Reset Timing (FS mode)
Figure 28.
Issuing resume
This section describes how to enable automatic resume to be triggered by some cause when remote wakeup
is supported and the remote wakeup function is enabled from the host.
Remote wakeup can only be enabled 5 ms after the bus enters the Idle state. Furthermore, the current used
before the USB Suspend state cannot be pulled from the VBUS until 10 ms has elapsed after the Resume
signal output.
The S1C33L26 supports Snooze state. This section describes the operation for issuing Resume when the
oscillation circuit is in operation (USBCLK_EN/CMU_CLKCTL register = 1, not in Sleep). Steps (3), (4),
(8) and (9) below are handled by the macro hardware automatically. Perform steps (1), (2), (6), (6a) and (10)
on the firmware that controls this macro.
(1) Clear the SIE_IntEnb.EnNonJ and USBSNZ bits. This is to cause this macro return from Snooze for
automatic wakeup.
(2) Set the USB_Control.SendWakeup bit and send out the Resume signal.