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Altera_Forum's avatar
Altera_Forum
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17 years ago

Error: Cannot drive signal 'data' of mode IN

Hi, I am new user to ModelSim and writing VHDL code.. I've got the follwing msg when I compiled a vhdl code "Error controller.vhd(64): Cannot drive signal 'data' of mode IN." ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

If I understand right, you are trying to assign a value to a port signal of IN type. This isn't possible by basic VHDL rules - and can't create a meaningful logic behaviour, to my opinion. A signal can either be driven externally or from internal logic. If the signal source is intended to be changed during operation, a multiplexer would be necessary.