updated the makefile to create the build directory as needed.

makefile

@@ -1,9 +1,10 @@
 ASM=avra
 #INCLUDE=/opt/microchip/mplabx/v6.05/packs/Microchip/ATmega_DFP/3.0.158/avrasm/inc/m328pdef.inc
 INCLUDE=/opt/microchip/mplabx/v6.05/packs/Microchip/ATmega_DFP/3.0.158/avrasm/inc/
-SRC=./src/main.s
-OUT=./build/prog
-MAPFILE=./build/prog.map
+SRC=./src
+PROG=main
+OUT=./build
+MAPFILE=prog.map
 
 F_CPU=1000000UL
 MCU=atmega328p
@@ -17,20 +18,22 @@ OBJDUMP = avr-objdump
 AVRSIZE = avr-size
 AVRDUDE = avrdude
 
-PROG=./src/main.s.hex
+#PROG=${OUT}/main.asm.hex
 
 all:
-	${ASM} -I ${INCLUDE} ${SRC} -o ${OUT} -m ${MAPFILE}
+	if [ -d ${OUT} ]; then return 0; else mkdir ${OUT}; fi
+	${ASM} -I ${INCLUDE} ${SRC}/${PROG}.asm -I ${OUT}/${PROG}.hex -m ${OUT}/${MAPFILE}
+	mv ${SRC}/*.hex ${OUT}
+	mv ${SRC}/*.obj ${OUT}
+	mv ${SRC}/*.cof ${OUT}
+
 
 flash: ${PROG} 
 	$(AVRDUDE) -c $(PROGRAMMER_TYPE) -p $(MCU) $(PROGRAMMER_ARGS) -U flash:w:$<
 
 clean:
-	if test -e ${SRC}.hex; then
-		echo "cleaing hex files!";
-		rm ${SRC}.hex;
-	done;
-	fi
+	echo "cleaing hex files!";
+	rm ${OUT}/*
 
 flash_usbasp: PROGRAMMER_TYPE = usbasp
 flash_usbasp: PROGRAMMER_ARGS =  # USBasp works with no further arguments