After my EPM7128LC84-6 was auto assigned pins ,I found that the 84th pin(INPUT/OE1) was assigned as a 'in' pin. The 1st pin(INPUT/GLCRn) and the second pin(INPUT/OE2) were 'GND'.What should i do,trust them or amend them?
After my EPM7128LC84-6 was auto assigned pins ,I found that the 84th pin(INPUT/OE1) was assigned as a 'in' pin. The 1st pin(INPUT/GLCRn) and the second pin(INPUT/OE2) were 'GND'.What should i do,trust them or amend them?
You should assign the pin according your CPLD's pin connection on the PCB, the software assigns these "INPUT/GLCRn) and the second pin(INPUT/OE2) were 'GND' " is that these pin is not used in your design, it is best to tie them to GND.
1. First allow the FPGA software to route your initial design and give you a set of pin allocations.
2. Design your PCB based on this pin assignment and FIX this pin assignment so that any future iterations of resynthesis and P&R will not deviate much from this pin assignment.
Generally the pin assignment provided by the FPGA P&R tool is optimized for its P&R.
And of course reserve plenty of IOs to external connectors on your board in case you want to use extra signals.