AR# 4678: map 1.4:ERROR:baste:263 - The LOC constraint "P21" (a IOB location) is not valid..
map 1.4:ERROR:baste:263 - The LOC constraint "P21" (a IOB location) is not valid..
Keywords: map, alliance, leonardo
General Description: Trying to source a global clock buffer from a non-dedicated clock I/O. In VHDL, by making a signal assignment to the input signal in order to force an ibuf between the input signal and the clock buffer.
When the design is run through MAP, M1 falls over with the error:
ERROR:baste:263 - The LOC constraint "P21" (a IOB location) is not valid for symbol "reset_200msn.PAD" (pad signal=reset_200msn), which is being mapped to the following site types: CLKIOB
Leonardo optimizes the ibuf out which is reflected in the resulting netlist.
The reason this has occurred is because the netlist dictates that the clock signal comes into the device and directly into the input of a global buffer. However, because the clock signal is not placed to an IOB with this direct access to a global buffer, this is an illegal connection.
The solution is to insert an input buffer between the pad and the global buffer.