Different Output Voltage to IO (3.3 and 1.2)

Hi,

I want to set my output pins such that some of the pins can generate 1.2V and some of the pins can generate 3.3V. I tried to do this by changing IOSTANDARD in the UCF file.

For example, I would have

NET “a” LOC=U20 | IOSTANDARD=LVCMOS33; #JP2-42
NET “a” DRIVE = 2;

NET “b” LOC=L17 | IOSTANDARD=LVCMOS12; #JP3-41
NET “b” DRIVE = 2;

I got the following errors:
Place:864 - Incompatible IOB’s are locked to the same bank 1
ERROR:Pack:1654 - The timing-driven placement phase encountered an error.

Can someone please help me and suggest the proper way of doing this on XEM6110-LX45?

Many thanks.

Please refer to the Spartan-6 Select IO documentation.

Individual outputs cannot be set to arbitrary voltage standards. You need to establish voltage standards for entire banks.