AR# 3205: 1.5i Foundation Logic simulator - Bus ordering reversed after bus has been flattened, then combined
1.5i Foundation Logic simulator - Bus ordering reversed after bus has been flattened, then combined
The confusion lies in the function of the Flatten and Combine options.Bus -> Flatten actually breaks the bus. After you have peformed a Bus -> Flatten, the bus is no longer a bus. When you perform Bus -> Combine, it creates the bus. When the bus is Combined, the bit order is determined by the order in which the signals are listed in the Simulator window.The top-most bit becomes the LSB.Note that even if BIT7 is on top, and BIT0 on the bottom of the list, BIT7 is the LSB after you do a Bus -> Combine.
This icon performs the function of simply expanding and collapsing the bus to be able to VIEW the individual bits.This is different than the Bus -> Flatten and Bus -> Combine which actually break and create the bus. With the Buses icon, the bus always remains a bus, but what changes is the view of it, ie, whether you see it as a bus or as indivual bits.
In case the bit order or your bus has been switched, (by inadvertantly using the Bus -> Flatten, Bus -> Combine) you can restore the correct order by selecting: