OneAccess Crocus CNV - Special Points of Interest Concerning Clocking on the X21 Interface

Step-by-step configuration Crocus CNV
64 User manual
5.3.5 Special points of interest concerning clocking on the X21 interface
The following are some special points of interest concerning clocking on the X21 interface:
• In internal clocking modes, the S clock is the transmit clock. There is always a retiming buffer in the
receive direction (slave transmit), independent of the rxClk attribute value. The receive data is clocked
out with the internal clock.
• In slave receive clocking modes, the transmit and receive clocks are the same. Hence, there is no
difference with other interfaces.
• In external clocking mode, the S clock is the receive clock.
• It is possible to invert the transmit sample clock on the X21 interfaces. In case of alternative clocking
modes, inversion solves the possible problem of too long delays on the transmit data (from DTE to
DCE) in comparison to the transmit clock (from DCE to DTE). The inversion can be done by means of
DIP switches (refer to Section 3.2.3 - DIP switches of the Card Version).