comment of pins in UCF

[saman1969]

Hi , I thought by commenting a pin in UCF file (by # sign) in program(VHDL)it is considered as 'Z' , and has no role in the chip , in a project for driving a camera for getting view in LCD , i allocated 8 pins for each color R,G,B . in first try i used all pins in code but commented R and G pins and in second try i repeated test but did not used those pins in code . normally i thought that result of these two test would be same . but it did not . at second try lcd had a blue view but in first try view was not blue . shouldnt these two try had the same result?
where i make mistake? thanks

 

[ads-ee]

Sigh, another post lacking useful information...Making huge assumptions about your "invisible code" and your "invisible UCF file".

You can't just comment out the pin location constraints in a UCF file and expect something to keep working. The pin location constraints are used to place the input and output ports of your top level file on pins that are attached to specific hardware on the board the FPGA is mounted on. If you don't supply pin locations the place and route tools are free to put the pins anywhere it likes including possibly on pins that are supposed to be used as inputs (driven by another device) and are now configured as outputs due to removing the placement constraint.