Revamp rp examples

tutorials/rp/pico-rm2/Makefile

@@ -0,0 +1,37 @@
+# Environment setup: https://mongoose.ws/docs/getting-started/build-environment/
+
+CWD ?= $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
+SDK_PATH ?= $(CWD)/pico-sdk
+RM = rm -rf
+MKBUILD = test -d build || mkdir build
+
+ifeq ($(OS),Windows_NT)
+  RM = cmd /C del /Q /F /S
+  MKBUILD = if not exist build mkdir build
+endif
+
+.PHONY: build
+
+all build example: build/firmware.uf2
+
+build/firmware.uf2: pico_sdk_import.cmake mongoose/mongoose.c mongoose/mongoose.h
+
+pico_sdk_import.cmake: $(SDK_PATH)
+	cp $(SDK_PATH)/external/$@ $@
+
+mongoose/mongoose.c mongoose/mongoose.h:
+	cp ../../../$(notdir $@) $@
+
+build/firmware.uf2: $(SDK_PATH) $(wildcard *.[ch]) CMakeLists.txt Makefile
+	$(MKBUILD)
+	cd build && PICO_SDK_PATH=$(SDK_PATH) cmake -G "Unix Makefiles" .. && make
+
+flash: build/firmware.uf2
+	picotool load $< -f
+
+clean:
+	$(RM) build pico_sdk_import.cmake mongoose/mongoose.c mongoose/mongoose.h $(SDK_PATH)
+
+$(SDK_PATH):
+	git clone -c advice.detachedHead=false --quiet --depth 1 -b 2.1.1 https://github.com/raspberrypi/pico-sdk $@
+	cd $@ && git submodule update --quiet --init