Resolved ICESugar pro blink.v :
ERROR: Module rst_gen contains processes, which are not supported by JSON backend (run `proc` first). Edit Makefile $(TARGET).json: $(OBJS) # yosys -p “synth_ecp5 -json $@” $(OBJS) yosys -p “read_verilog -sv $<” -p “synth_ecp5 -json $@” $(OBJS)