w6691 Winbond Electronics Corp America, w6691 Datasheet - Page 26

• Manufacturer Part Number: w6691
• Description: Isdn S/t Interface Transceiver
• Manufacturer: Winbond Electronics Corp America

7.2.3 Layer 1 Activation/Deactivation
TE/LT-T/LT-S mode. The state transitions are triggered by signals received at S interface or commands issued
from microprocessor. The state outputs signals to S interface and indication to microprocessor. The CIX
register is used by microprocessor to issue command, and the CIR register is used by microprocessor to
receive indication.
continuous zeros" and "send single zero".
7.2.3.1 States Descriptions And Command/Indication Codes in TE/LT-T
F3 Deactivated without clock
reset pulse. After reset, once the indication "1111" has been read out, internal clocks will turn off and stay at
this state if INFO 0 is received on the S line. The turn off time is approximate 93 ms. The ECK command must
be issued to activate the clocks.
F3 Deactivated with clock
entered by the ECK command.
command, depending on the crystal capacitances. (It is about 0.5 ms for 12pF to 33pF capacitance).
F3 Awaiting Deactivation
constant prevents spurious effect on S interface. Any non-INFO 0 signal on the S interface causes transition to
"F5 Identifying Input" state. If this transition does not occur in a specific time (500 - 1000 ms), the
microprocessor may issue DRC or ECK command to deactivate layer 1.
F4 Awaiting Signal
transmits INFO1 and INFO 0 is received from the S interface. The software starts timer T3 of I.430 when
issuing activate request command. The software deactivates layer 1 if no signal other than INFO 0 has been
received on S interface before expiration of T3.
The layer 1 activation/deactivation procedures are implemented by a finite state machine according to
Some commands are used for special purposes. They are "layer 1 reset", "analog loopback", "send
This is the "deactivated" state of ITU-T I.430. The receive line awake unit is active except during a hardware
This state is identical to "F3 Deactivated without clock" except the internal clocks are enabled. The state is
The W6691 enters this state after receiving INFO 0 (in states F5 to F8) for 16ms (64 frames). This time
This state is reached when an activate request command has been received. In this state, the layer 1
The clocks are enabled approximately 0.5 ms to 4 ms after the ECK
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Preliminary W6691
Publication Release Date: Sep 2001
Revision 1.1