Reset Detection In Hs Mode - Epson S2R72V18 Technical Manual

1. Functions
1.3.7.2.3

Reset Detection in HS Mode

If a reset is detected in HS mode, a DetectRESET interrupt status is issued and the auto
negotiator performs the reset sequence. The XINT signal is asserted if the
D_SIE_IntEnb.EnDetectRESET bit or USB_DeviceIntEnb.EnD_SIE_IntStat bit is set here
and MainIntEnb.EnUSB_DeviceIntStat is set.
The auto negotiator switches to FS mode automatically if no transmission is sent or received
within 3 ms (HS termination is disabled and FS termination (Rpu) is enabled). If reset, the
DP line remains at "L" even when this operation is performed. This allows detection of
"SE0" even with the D_USB_Status.LineState[1:0] bit. The D_SIE_IntStat.DetectRESET bit
is set if "SE0" is still detected at point T2. The D_NegoControl.DisBusDetect bit is then set
before performing the HS Detection Handshake (described later).
time
XcvrSelect
TermSelect
DetectRESET
DisBusDetect
LineState[1:0]
DP / DM
Timing
Parameter
T0 Last bus activity.
T1 XcvrSelect and TermSelect are set to "1," and the LSI
switches from HS mode to FS mode if there is still no bus
activity detected at this point.
T2 Samples LineState[1:0]. If "SE0" is detected here,
DetectRESET is set to "1," and the LSI determines a transition
to reset. Sets DisBusDetect to "1" after detecting a reset
command, then performs the HS Detection Handshake.
Note: Brackets {} indicate names defined in the USB 2.0 standards.
30
T0
SE1
Last
Activity
Driven SE0
HS Mode
Fig. 1-11 Reset timing (HS mode)
Table 1-12 Reset timing values (HS mode)
Description
T1
EPSON
S2R72V18 Technical Manual (Rev.1.00)
T2
SE0
FS Mode
HS Detection
Handshake
Value
0 (reference)
HS Reset T0 + 3.0 ms < T1 {T
HS Reset T0 + 3.125 ms
T1 + 100 µs < T2 {T
WTWRSTHS
T1 + 875 µs
} <
WTREV
} <