Bus contention checking
Bus contention checking detects bus fights on nodes that have multiple drivers. A bus fight occurs when two or more drivers drive a node with the same strength and that strength is the strongest of all drivers currently driving the node. The following table provides some examples for two drivers driving a std_logic signal:
driver 1 driver 2 fight Z Z no 0 0 yes 1 Z no 0 1 yes L 1 no L H yesDetection of a bus fight results in an error message specifying the node and its drivers' current driving values. If a node's drivers later change value and the node is still in contention, a message is issued giving the new values of the drivers. A message is also issued when the contention ends. The bus contention checking commands can be used on VHDL and Verilog designs.
These bus checking commands are in "Commands" :
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