Help: ICE_GENERAL_CLOCKING

Clock sources and selection


Most IO Modules provide their own clock, either derived from the data or 
from an external source.  

The two IO Module sites on ICE cards can operate independently or from a 
global muxed clock.  The global clock is necessary when:

 1) Multiplexing data from the A and B ports 
 2) VeryHighSpeed mode when the resources from both ports are bridged
 3) Synchronizing sampling clocks to both modules
 3) Driving a module without its own clock source (i.e. D2E,D2T)

The IOC code _II is for 2 independent input modules, each with their own clock.
The IOC code _IIX is for 2 inputs with a global muxed clock.
The IOC code _IO or _OI is for 1 input and 1 output.  The input gets its 
  clock from the module, the output from the global muxed clock.
The IOC code _OO is for 2 outputs with a global muxed clock.

To set the source for the global muxed clock, add the MUXCLK=s flag to the
card configuration string handed to the pic_open() call.

There 7 possible sources for the muxed clock signal:
 
   s=N No MUXCLK
   s=I Internal clock = 40MHz/N where (N=1,1024)
   s=X External clock SMB on series 3/4 card edge
   s=A Module A input clock (or s=1)
   s=B Module B input clock (or s=2)
   s=C Alternate Crystal CCLK on series 3/4 cards
   s=D Alternate Crystal CCLK/N where (N=1,16)
   s=P Programmable Clock on series 4 cards (.1 to 105 MHz)
   s=PX Programmable Clock using the external reference (PREFX)

When using the global clock, the CLKI flag can be used to invert the clock.
The DEGLITCH flag will run the A and B sources through a deglitching circuit.