W6694 Datasheet, PDF (17/33 Pages) Winbond – USB Bus ISDN S/T-Controller

Preliminary W6694
XDOV Transmit Data Overflow
The corresponding XFIFO has overflow condition. Data in XFIFO are overwritten by incoming
USB data. For D and B channel, the XFIFO is reset and disabled for that channel. This bit is
cleared when XFIFO is enabled by XEN bit.
RDOV Receive Data Overflow
The corresponding RFIFO has overflow condition. Data in RFIFO are overwritten by incoming
ISDN data. When overflow condition occurred, the D and B channel RFIFO is reset and
disabled for that channel. This bit is cleared when RFIFO is enabled by REN bit.
7.1.8 Suspend and Resume
W6694 supports USB suspend and resume function as described in USB specification 1.1. When
there is more than three millisecond period of inactivity on the USB, W6694 will automatically enter
into a low-power suspend state. In this state, most of the ISDN and USB module will be powered off
to consume minimum power. But the internal register values are preserved. Therefore it is
recommended that the software perform necessary control to W6694 before power-down. The W6694
will leave suspend mode only when one of the two condition happens: host or device wake-up. A
ISTA:WAKE bit will indicate to software which source the wake-up event is originated from.
(i). Host-Initiated Wake-up
The USB host may wake-up W6694 by sending traffic on USB. On detected this wake-up signal,
W6694 will automatically resume to normal operation.
(ii). Device Remote Wake-up
In suspend mode, W6694 will ignore any ISDN traffic on S/T bus, except for incoming broadcast
messages. When there is an incoming broadcast message from ISDN switch, such as SETUP
message, W6694 will automatically wake-up, and signal the USB host that it has left suspend mode.
The incoming SETUP message will be saved in D channel RFIFO. After returning from suspend
mode, software should immediately read the RFIFO, and perform necessary operation as specified in
ISDN protocol.
7.2 Configuration EEPROM
A 9346/93C46 type serial EEPROM can be used to store customized USB device configuration data.
These configuration data will be read by W6694 after power on or reset, and sent to the USB host
during enumeration. If EEPROM is not presented, or the first 16 bits in EEPROM is FFFFh, the
default value in W6694 will be sent to the USB host instead.
EEPROM wire connection:
W6694
EEPROM
EPCS
EPCS
EPSK
EPD
O
EPDI
Chip
Select
Serial Clock
Data In
Data Out
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Publication Release Date: October 2000
Revision A1