ID:13065 The bidirectional pin "<name>" is fed by multiple output buffers

CAUSE: The specified bidirectional pin has fan-ins from multiple output buffers. This is illegal. This can happen, for example, if multiple bidirectional I/O primitives are connected to the same bidirectional pin. So, the following usage results in this error.

     input i1, i2, oe; 
    output o1, o2; 
    inout bidir; 
    alt_iobuf my_iobuf1 (.i(i1), .oe(oe), .o(o1), .io(bidir)); 
    alt_iobuf my_iobuf2 (.i(i2), .oe(oe), .o(o2), .io(bidir)); 
    
            

This can also happen if a differential bidirectional I/O primitive has its positive and negative ports both connected to the same bidirectional pin. So, the following usage also results in this error.

     input i1, oe; 
    output o1; 
    inout bidir; 
    alt_iobuf_dff my_iobuf_diff (.i(i1), .oe(oe), .o(o1), .io(bidir), .iobar(bidir)); 
    
            

Additionally, this error can also occur if a third party Synthesis tool makes an error while generating the synthesized output.