Add UART test code

Makefile

@@ -0,0 +1,22 @@
+buildpath = build/
+filename = uart_test
+files = top.v
+pcf_file = io.pcf
+
+.PHONY: build prog prog_flash clean
+
+build:
+	#yosys -p "synth_ice40 -blif $(buildpath)$(filename).blif -top top" $(files)
+	#arachne-pnr -r -d 5k -P sg48 -p $(pcf_file) $(buildpath)$(filename).blif -o $(buildpath)$(filename).asc
+	yosys -p "synth_ice40 -json $(buildpath)$(filename).json -top top" $(files)
+	nextpnr-ice40 --up5k --json $(buildpath)$(filename).json --pcf $(pcf_file) --asc $(buildpath)$(filename).asc
+	icepack $(buildpath)$(filename).asc $(buildpath)$(filename).bin
+
+prog: build #for sram
+	iceprog -S $(buildpath)$(filename).bin
+
+prog_flash: build
+	iceprog $(buildpath)$(filename).bin
+
+clean:
+	rm -rf $(buildpath)/*