Electronic – Why can’t I assign pin 18 on Lattice MachXO2-256-HC FPGA in the design

fpgalattice

I'm using a Lattice spreadsheet view inside of Diamond with a MachXO2-256-HC-4TG100C. When I assign pin 18 to a port on my design, I get an error:

ERROR - The pin [18] is not user assignable and cannot be assigned to the port [clk_sel_in]; for details, please refer to the device datasheet.

  • phys pin on board is connected to slide switch, gnd on one side, n/c on other side, pulled up in fpga.
  • datasheet says pin 18 is just PL7B on Bank 1
  • there are no special functions associated with the pin.
  • all special functions (except JTAG) are disabled just in case in global preferences
  • I don't see any asterisks anywhere in DS1002 for the pin/package.
  • Other datasheets / docs I've checked TN1199, DS1035, TN1204, DS02056, Design Planning Guide, Diamond Users Guide.

I've only used one lattice on one other project so very possible I'm doing something silly or don't understand something about how they do things. Does anyone know what may cause this? I'm using Lattice Diamond 64-bit on Windows version 3.11.2.446. Thanks in advance.

Best Answer

The pinout files for your device can be found here. Based on the "MachXO2-256 Pinout" document, looking at the TQFP 100 package ("TG100" from part number):

Table Excerpt

We see that Pin 18 is a No-Connect pin.


Looking further, did you read "18" from the "PAD" column? (That would be PL5B). That corresponds to pin 17 of the TQFP package, not pin 18.

Excerpt from table

Related Topic