Microcontroller VU

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182.694 Microcontroller VU Martin Perner SS 2017 Featuring Today: A Deep Look into the Processor Core Getting Code onto the Microcontroller Chip Weekly Training

2.5 Digital I/O 2.4.1 precompiled LCD Until Exam 2.2.3 LED Rain 2.2.8 LED curtain 2.4.2 Calling conventions I 2.4.3 Calling conventions II Martin Perner Microcontroller Basics March 6, 2017 2 Organizational Stuff Make your slot suggestions in myti (https://ti.

1 Microcontroller VU Martin Perner SS 2017 Featuring Today: A Deep Look into the Processor Core Getting Code onto the Microcontroller Chip Weekly Training Objective This week 1.2 Board test Assembler demo program Makefile Logical operations Next week Input with floating pins Monoflop buttons Digital I/O precompiled LCD Until Exam LED Rain LED curtain Calling conventions I Calling conventions II Martin Perner Microcontroller Basics March 6, Organizational Stuff Make your slot suggestions in myti ( Martin Perner Microcontroller Basics March 6, Use the lab!

2 Organizational Stuff Slots The Tutors will be in the lab for 3 hours at a time. Check for the exact times. Your slot suggestions are for one hour in the lab, during a tutor slot. During your assigned slot you have priority for a microcontroller-target. Nonetheless, you can work at any time in the lab (not limited to tutor hours), given that the lab is open. Check the timetable on the TILab homepage! Martin Perner Microcontroller Basics March 6, A Deep Look into the Processor Core We are using Atmel AVR microcontroller in lab Overview not restricted to AVR Every microcontroller works nearly the same In-depth knowledge of a CPU inner workings are taught in Computer Organzation and Design (3. semester BTI) AVR Core Martin Perner Microcontroller Basics March 6, Martin Perner Microcontroller Basics March 6,

3 A Microcontroller Executable Motorola S-Record File: (*.srec) S00C D6F2E S C940C002F93202F015618F F07E S F2F FEF0DBF01E20EBF62 S E002B90FEF01B904E40EBB00E00FBB1E S F00E B90C941800C6 S C C6C6F20576F726C6421AF S A S FC Is a printable form of an exe file for a microcontroller. Martin Perner Microcontroller Basics March 6, Motorola S-Record Format Record Type (S1) S0 Block Header S1-3 Data Records S5 Record Count S7-9 End of Block S C940C002F93202F015618F F07E Byte Count (0x13) Address + Data + Checksum Address (0x0000) Data (only for S0-3) Checksum (0x7E) (ones complement of the sum of: byte count, address bytes, and data bytes) & 0xFF Martin Perner Microcontroller Basics March 6, A Microcontroller Executable Intel Hex File: (*.hex) : C940C002F93202F015618F F082 : F2F FEF0DBF01E20EBF66 : E002B90FEF01B904E40EBB00E00FBB22 : F00E B90C941800CA : C C6C6F20576F726C6421B3 : E : FF Same data, other format. Martin Perner Microcontroller Basics March 6,

4 Intel Hex Format Start Code (:) Byte Count (0x10) Data only Address (0x0000) Record Type (00) 00 Data Records 01 EOF Record... Data : C940C002F93202F015618F F082 Checksum (0x82) (two s complement of the sum of: byte count, address bytes, record type, and data bytes) & 0xFF AVR Core Martin Perner Microcontroller Basics March 6, Instructions Martin Perner Microcontroller Basics March 6, : C940C002F93202F015618F F082 : F2F FEF0DBF01E20EBF66 : E002B90FEF01B904E40EBB00E00FBB22 : F00E B90C941800CA : C C6C6F20576F726C6421B3 : E : FF AVR Instructions 16/32 bit opcodes Instructions directly readable from hex file (little endian) e.g., 01E2 opcode 0xE b ldi r16, 0x21 (loads value 0x21 into register r16) Martin Perner Microcontroller Basics March 6,

5 AVR Core Register Martin Perner Microcontroller Basics March 6, : C940C002F93202F015618F F082 : F2F FEF0DBF01E20EBF66 : E002B90FEF01B904E40EBB00E00FBB22 : F00E B90C941800CA : C C6C6F20576F726C6421B3 : E : FF Used to perform operations ldi r16, 0x21 (loads value 0x21 into register r16) subi r16, 0x61 (subtract 0x61 from value stored in register r16) Store the result of operations Martin Perner Microcontroller Basics March 6, General Purpose AVR 32 GP Register à 8 bit Mapped into SRAM at first 32 addresses Some operations have restrictions on the use of registers, e.g., subi only works on registers 16 R26 31 can be used as 16 Bit address pointers X, Y, Z (see addressing modes) and are also accessible via XL, XH,... Martin Perner Microcontroller Basics March 6,

6 AVR Core Status Register Martin Perner Microcontroller Basics March 6, Special register containing information about result of the last (few) instruction I Global Interrupt Enable T T-bit (can be used for bit copy) H Half Carry Flag S Sign Bit (N XOR V) V Two s Complement Overflow Flag N Negative Flag Z Zero Flag C Carry Flag Status Register Martin Perner Microcontroller Basics March 6, Affected flags can be seen in the Instruction Set Flags can be used to determine program flow Martin Perner Microcontroller Basics March 6,

7 Flag Example AVR Core Martin Perner Microcontroller Basics March 6, Control Flow Martin Perner Microcontroller Basics March 6, Branch Flags in the status register can also be used for conditional branch (jump-if-statements). Very limited range, though! BREQ label1 ; jumps to label1 if Z=1 BRLO label2 ; jumps to label2 if C=1... Unconditional Jumps JMP (reaches complete memory range) RJMP (one cycle faster but smaller range) Martin Perner Microcontroller Basics March 6,

AVR Core RAM Martin Perner Microcontroller Basics March 6, 2017 22 General Purpose Register and IO-Register mapped into SRAM address range ATmega1280.

8 AVR Core RAM Martin Perner Microcontroller Basics March 6, General Purpose Register and IO-Register mapped into SRAM address range ATmega kb SRAM Multiple addressing modes Register Direct Data Direct Data Indirect (Pointer) Powerful displacement, pre-decrement, and post-increment modes! AVR Core Martin Perner Microcontroller Basics March 6, Martin Perner Microcontroller Basics March 6,

9 IO-Modules Configured by IO-Registers Digital IO Ports: DDRx, PORTx, PINx EEPROM: EEARH/L, EEDR, EECR Ext. Interrupts: EICRA, EIMSK, EIFR Timer UART... Detailed explanations in the manual Depend on used microcontroller IO-Modules Martin Perner Microcontroller Basics March 6, Attention Opcodes in and out only work on the 64 I/O Registers, not on the External ones! PORT{H,J,K,L}, TIMSK*, ADC,... are all in the External range Using lds/sts on the 64 I/O Registers directly does not work! The assembler only complains if you try in/out with a value > 64. There are comments in m1280def.inc, if you are unsure. Alternatively, Chapter 33 Register Summary of the ATmega1280 manual also lists these registers. AVR Core Martin Perner Microcontroller Basics March 6, Martin Perner Microcontroller Basics March 6,

10 Example Program. NOLIST. INCLUDE m1280def. inc. LIST ; Name t h e r e g i s t e r s you a r e u s i n g. ;. equ temp, 0 x10 ; r16. equ x, 0 x10 ; r16 (! ). equ temp1, 0 x11 ; r17. equ temp2, 0 x12 ; r18 ;. s e c t i o n. t e x t. g l o b a l main. org 0 x0000 ; r e s e t v e c t o r jmp main Unconditional Jump Function toupper : push temp2 mov temp2, x ; backup x i n temp2 s u b i x, ' a ' ; s u b t r a c t ' a ' from x b r l o e n d o f s u b ; i f x < ' a ' do nothing ; e l s e s u b i x, ' z ' 'a ' ; s u b t r a c t ' z ' 'a ' from x b r l o e n d o f s u b ; i f x 'a ' >='z' a '+1 ; do n o t h i n g. e l s e s u b i temp2, 0x20 ; t o u p p e r backup end of sub : mov x, temp2 ; r e s t o r e x pop temp2 r e t main : l d i temp, l o 8 (RAMEND) ; i n i t i a l i z e s t a c k p o i n t e r out SPL, temp l d i temp, h i 8 (RAMEND) out SPH, temp l d i temp, 0 x00 ; s e t PORTA to z e r o out PORTA, temp l d i temp, 0xFF out DDRA, temp Register ; and Direct i n i t i a l i z e as IO-Register Direct o u t p u t l d i temp, l o 8 ( mydata ) ; i n i t i a l i z e Z to p o i n t a t data out ZL, temp l d i temp, h i 8 ( mydata ) out ZH, temp l o o p : Program Indirect lpm temp, Z+ ; r e a d data from f l a s h Post ; u s i n gincrement p o s t i n c r e m e n t c p i temp, 0 x00 breq end Conditional ; got t e r mjump i n a t i o n c a l l t o u p p e r Function ; c a l l t o ucall p p e r ( temp ) out PORTA, temp ; o u t p u t jmp l o o p end : jmp end mydata :. b y t e 'H', ' e ', ' l ', ' l ', ' o ', ' ', 'W', ' o ', ' r ', ' l ', ' d ', '! ', '\0 ' Martin Perner Microcontroller Basics March 6, Getting Code onto the Microcontroller Chip Starting with an assembler program... How do we get a running program on the microcontroller? Martin Perner Microcontroller Basics March 6, Starting with an Assembler File Assembler file not directly download-able because file is not binary includes (m1280def.inc) names of registers (temp) calculations ( z - a ) jump-labels (toupper) comments... Martin Perner Microcontroller Basics March 6,

11 Starting with an Assembler File File needs to be assembled so that... mnemonics are replaced by their opcodes includes directives are resolved register-names are translated to addresses calculations are replaced by their results jump-labels are replaced by addresses comments are removed... Martin Perner Microcontroller Basics March 6, Easy Way Makefile Use Makefile and type make and make install to assemble and download a program Problem Makefile might not be there (e.g., new toolchain or first MC exam!) Solution Get to know the toolchain and learn how to write a Makefile (Ex 2.1.2) Martin Perner Microcontroller Basics March 6, Short Makefile Primer Targets A Makefile consists of targets. A target can have dependencies (files, other targets). The target s name is a file which will be created by the target (exception: phony targets). The first target in the Makefile is the default target. Targets can have patterns, e.g., %.c matches c-files. Usually there are implicit targets shipped with Make. You can try make -n -p to see the effective Makefile used. Martin Perner Microcontroller Basics March 6,

12 Short Makefile Primer.PHONY: clean demo.elf: demo.s avr-as -mmcu=atmega1280 -o demo.o demo.s avr-ld -mavr51 -o demo.elf demo.o clean: rm -f demo.o demo.elf Note: Indentations in Makefile must be with tabulator! Spaces will not work! Martin Perner Microcontroller Basics March 6, Short Makefile Primer demo.o: demo.s avr-as -mmcu=atmega1280 -o demo.o demo.s demo.elf: demo.o avr-ld -mavr51 -o demo.elf demo.o Martin Perner Microcontroller Basics March 6, Short Makefile Primer This looks nice. But what if you have a different file name, e.g., main.s? Variables You can define variables to, e.g., allow for simple file renaming. Variables can be set in the shell environment. Using $(CC) or $(CFLAGS) may also be benefical. Make has automatic variables. They are very useful with pattern targets, e.g., $@ holds the (expanded) name of the target. Martin Perner Microcontroller Basics March 6,

13 Short Makefile Primer FILENAME MCU ARCH AS LD ASFLAGS LDFLAGS = main = atmega1280 = avr51 = avr-as = avr-ld = -mmcu=$(mcu) = -m$(arch) all: $(FILENAME).elf $(FILENAME).elf: $(FILENAME).s $(AS) $(ASFLAGS) -o $(<:.s=.o) $< $(LD) $(LDFLAGS) -o $@ $(@:.elf=.o) Martin Perner Microcontroller Basics March 6, Short Makefile Primer TARGETNAME = main.elf [...] all: $(TARGETNAME) %.o: %.s $(AS) $(ASFLAGS) -o $@ $< %.elf: %.o $(LD) $(LDFLAGS) -o $@ $< Martin Perner Microcontroller Basics March 6, Short Makefile Primer Can we get even shorter? $ make -p -f/dev/null [...] COMPILE.s = $(AS) $(ASFLAGS) $(TARGET_MACH) [...] %.o: %.s # recipe to execute (built-in): $(COMPILE.s) -o $@ $< [...] Note: this depends on the implict rules available! Martin Perner Microcontroller Basics March 6,

14 Short Makefile Primer FILENAME MCU ARCH AS LD ASFLAGS LDFLAGS = main.elf = atmega1280 = avr51 = avr-as = avr-ld = -mmcu=$(mcu) = -m$(arch) all: $(FILENAME) %.elf: %.o $(LD) $(LDFLAGS) -o $@ $< Martin Perner Microcontroller Basics March 6, Generating an Executable for a Microcontroller file1.s Assembler file1.o file2.s Assembler file2.o Linker project.elf / project.out avr-as Libraries avr-ld can be done inside avrprog2 project.elf / project.elf project.out Locator flash.hex eeprom.hex Programmer MC avr-objcopy avrprog2 Martin Perner Microcontroller Basics March 6, Generating an Executable for a Microcontroller Assembler Transforms mnemonics into opcodes (binary) Performs inline calculations Includes other files Linker Links multiple files Calculates addresses (Jumps to ISR!) Martin Perner Microcontroller Basics March 6,

15 Generating an Executable for a Microcontroller file1.s Assembler file1.o file2.s Assembler file2.o Linker project.elf / project.out avr-as Libraries avr-ld can be done inside avrprog2 project.elf / project.elf project.out Locator flash.hex eeprom.hex Programmer MC avr-objcopy avrprog2 Martin Perner Microcontroller Basics March 6, Generating an Executable for a Microcontroller project.elf Needs to be split to adhere to the physical realization of microcontroller (Flash, EEPROM, RAM).text Flash.eeprom EEPROM.data SRAM?!? RAM not directly programmable!!!!! in C initialized from Flash by init-code automatically linked into the program Done by avr-objcopy (or by the programmer) AVR - Toolchain Martin Perner Microcontroller Basics March 6, Features many other useful programs avr-objdump (disassemble object files) avr-size... These programs have various options Martin Perner Microcontroller Basics March 6,

16 Programming Typical Programming Interfaces Parallel SPI JTAG (also debugging capabilities) Bootloader (read executable from an interface) Thus, there are various programmers Programming Martin Perner Microcontroller Basics March 6, avrprog2 Used in the lab USB host interface SPI target interface UNIX command line interface (maintained by us) Not only Flash and EEPROM are programmable, but also Fuses (WARNING know what you are doing no need to change anything at the lab hardware) Lock Bits Martin Perner Microcontroller Basics March 6, Questions? Martin Perner Microcontroller Basics March 6,

EE 308: Microcontrollers

EE 308: Microcontrollers Introduction Aly El-Osery Electrical Engineering Department New Mexico Institute of Mining and Technology Socorro, New Mexico, USA January 6, 2018 Aly El-Osery (NMT) EE 308: Microcontrollers