Add Makefile

src/Makefile

@@ -0,0 +1,21 @@
+MCU    = attiny85
+# TODO: change frequency after moving to external oscillator
+F_CPU  = 1000000UL
+TARGET = main
+
+CC      = avr-gcc
+OBJCOPY = avr-objcopy
+
+# check if this is legit with assembly code only
+CFLAGS  = -mmcu=$(MCU) -Wall -Os -DF_CPU=$(F_CPU)
+
+all: $(TARGET).hex
+
+$(TARGET).elf: $(TARGET).S
+	$(CC) $(CFLAGS) -o $@ $<
+
+$(TARGET).hex: $(TARGET).elf
+	$(OBJCOPY) -j .text -j .data -O ihex $< $@
+
+clean:
+	rm -f *.elf *.hex