1758 - MachXO2: Can the MachXO2 device support PCI-compliant signaling on any GPIO?
Yes. However, there are considerations to keep in mind when choosing pins.
The MachXO2 implements two aspects of PCI buffers independently:
- PCI-level compliant inputs/outputs
- PCI complaint internal clamps.
MachXO2 implements PCI-level compliant inputs/outputs on all the IO (All Banks), but PCI complaint internal clamps are only available on the bottom bank (Bank 2).
In the Lattice Diamond software, specify IOTYPE=PCI33 and CLAMP=PCI in the spreadsheet view to force placement of the IO in Bank 2.
In some of the smaller MachXO2 device/footprint combinations, the number of pins available in Bank 2 may be fewer than required for typical PCI 32- or 64-bit data interfaces. In this case, the bus can be extended into others banks where external PCI-compliant clamping diodes may be utilized. For these IO, again set IOTYPE=PCI33, and set CLAMP to either 'OFF' or 'ON'.
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