Help: ICE_FLAGS_PREFX

This option uses the eXternal or clock pin as a reference for the Programmable Clock


This option uses the eXternal or clock pin as a reference for the Programmable Clock 
(MUXCLK=P) instead of the internal crystal.  It MUST be a stable 10 MHz sine wave 
present at all times.  The Programmable clock is a digital phase lock loop and will 
maintain a stable phase alignment with the reference clock.

For IO modules that have their own programmable clock (newer analog modules), the 
10MHz reference clock must be connected to the clock input on that module.

For older analog modules and most digital modules, the programmable clock is on the 
mainboard and the 10MHz clock must be connected to the eXternal pin at the center of 
the PCI card edge plate.

Note: On PIC4 and earlier cards, the PREFX flags must also be present during card reset
to load the correct IOC code into the FPGA.  PIC5 and later cards do this at runtime.
The PREFX flag should always be specified at runtime whether or not it is needed at reset.

Note: When using D2Ar9 modules, the PREFX=f can be used to specify a reference
frequency other than the 10MHz default.  For instance PREFX=20e6 is necessary to
generate clocks above 250MHz.  The internal reference is a 10ppm 20MHz crystal.