Introduction to AVR-STUDIO

Size: px

Start display at page:

Download "Introduction to AVR-STUDIO"

Jeffery Martin
6 years ago
Views:

DEPARTAMENTO DE TECNOLOGÍA ELECTRÓNICA ESCUELA TÉCNICA SUPERIOR DE INGENIERÍA INFORMÁTICA Introduction to AVR-STUDIO Computer Structure 1.

Writing assembler programs for the ATMEGA328P microcontroller and simulating its execution. Debugging using the AVR Simulator.

We will use the files shown in table 1 during the lab session. Some of the files must be completed as a previous work. Others will be completed during the session. Filename Description Notes sum.

1 DEPARTAMENTO DE TECNOLOGÍA ELECTRÓNICA ESCUELA TÉCNICA SUPERIOR DE INGENIERÍA INFORMÁTICA Introduction to AVR-STUDIO Computer Structure 1.Introduction and goals The goals of this session are the following: Using the AVR-STUDIO microcontroller programming and debugging environment from ATMEL 1. Writing assembler programs for the ATMEGA328P microcontroller and simulating its execution. Debugging using the AVR Simulator. We will use the AVR-STUDIO development environment to edit, debug, and simulate code for the Atmel AVR8 processor. AVR-STUDIO can be downloaded for free from the ATMEL web page ( We will use the files shown in table 1 during the lab session. Some of the files must be completed as a previous work. Others will be completed during the session. Filename Description Notes sum.asm order.asm median.asm A program to calculate the sum of numbers written in a table A program to order from lowest to highest numbers written in a table using 2's complement notation A program to count pulsations unsing BCD notation You must complete this before the lab session. You must complete this before the lab session. You must complete this during the lab session. Table 1. Files to be used during de lab session. It is mandatory to prepare and bring the programs described in the previous work to use them during the lab session. 1 A microcontroller supplier, more info at

2 Computer Structure 2 2.Previous work You must write two assembler programs. The first one will sum numbers stored in a table. The second will order a list of numbers (least to greatest). These programs are detailed bellow: 1.Program SUM: The program must sum a table of numbers starting at memory location table. Each number is coded in a location using 2's complement notation. The result must be coded in a 16-bit 2's complement notation (the most significant part in register R1 and the least significant part in register R0). The program must follow an algorithm similar to the following: X table address count table size result 0 while (count > 0) temp data_mem[x] X X+1 if ( temp>0) sign_extension $00 else sign_extension $FF end if result result + (sign_extension:temp) count count-1 end while list 1. algorithm for sum.asm. In order to write the program just complete the file sum.asm:.include "m168def.inc" // Include IO address definitions, register alias, bits....equ tablesize=... //table size //variable definitions.def temp=r16.def count =r18... //code segment.cseg.org 0 //The firs instruction will be stored at position 0 call initab //this will copy the table from EPROM to SRAM starting at memory position $100 suma: ldi xl,low(table) ldi xh,high(table) // X table... //write here the missing code end: jmp end initab: push r0 push temp push yl push yh push zl push zh ldi zl, low(2*tablaeeprom) ldi zh, high(2*tablaeeprom) ldi yl, low(table) ldi yh, high(table) ldi temp,tablesize loop: lpm r0,z+

3 Computer Structure 3 st Y+,r0 subi temp,1 brne loop pop zh pop zl pop yh pop yl pop temp pop r0 ret /*modify this list. Write any list of numbers*/ TablaEeprom:.db 10, 4, -1, 0, 0, 6, 3, 10, 100, -100, 24, 23, -56, 4, 15, 16.dseg.org $100 table:.byte tablesize //space reserved for the table list 2. file sum.asm 2.Program order: This program must order a table of numbers from least to greatest. Num_Rep table size do X table address Y X+1 Num_Rep Num_Rep -1 count Num_Rep ordered true do a data_mem[x] b data_mem[y] if (a > b) data_mem[x] b data_mem[y] a ordered false end if X X +1 Y Y +1 count count -1 while count > 0 while ordered = false list 3. algorithm for order.asm In order to write the program just complete the file order.asm:.include "m168def.inc".equ tablesize=....def Ordered=r17... //table size //define variables here.cseg.org 0 call initab //this will copy the table from EPROM to SRAM starting at memory position $100 //here the order algorithm Order: ldi NumRep, tablesize // Num_Rep <- tablesize

4 Computer Structure 4... end: jmp end //to finish initab: /* This is the same function of the file sum.asm */... ret TablaEeprom:.db 10, 4, -1, 0, 0, 6, 3, 10, 100, -100, 24, 23, -56, 4, 15, 16 ;/*modify this list. Write any list of numbers*/.dseg.org $100 table:.byte tablesize //space reserved for the table list 4. file order.asm 3.Lab work First you must execute the program of the previous work using the AVR-STUDIO development environment. Then you will have to complete and verify programs using some code from the programs of section 2. Make sure you have all the files listed in table An introduction to AVR-STUDIO You will execute the programs from the previous work using the AVR-STUDIO development environment. The process to create and carry out an AVR project is described in this section. Init AVR-STUDIO. The wizard depicted at fig 1 will pop up. It will let us create a project or open and existing one. If the wizard does not appear open the Project menu and choose the Project Wizard option. Figure 1. Project Wizard window Push the New Project button and the window depicted at fig. 2 will pop up. Fill in the project name, the project directory and enable the Atmel AVR Assembler option. If you enable the Create initial file option, an empty text file will be created where you will have to write your program. If you do not enable it, no new file will be created (useful if the assembler program file already exist).

Computer Structure 5 Figure 2. Type and program name selection After pushing the Next button, the window depicted at fig. 3 will appear.

If you did not enable the Create initial file option, you will have to add the file with your program to the project.

Choose the Add files to project option to add the desired assembler file. Figure 4.

5 Computer Structure 5 Figure 2. Type and program name selection After pushing the Next button, the window depicted at fig. 3 will appear. In this last window you must choose the options AVR Simulator and ATMega328P. Figura 3. Device and platform selecton. If you did not enable the Create initial file option, you will have to add the file with your program to the project. To do so right-click on the root of the project tree. The floating menu depicted if fig. 4 will appear. Choose the Add files to project option to add the desired assembler file. Figure 4. Adding files to the project After this the name of the added assembler file wile be shown at the project tree. You can edit this file by double-clicking on the file name. Once you have finished writing the program you will have to assemble the code. To do so choose the Build option from the Build or clicking on the icon from the tool bar. If everything is right information about the compiled program will be displayed at the lower part of the window:

6 Computer Structure 6 AVRASM: AVR macro assembler (build 1796 Sep :48:36) Copyright (C) ATMEL Corporation F:\EdC\tema4\practicas\solsuma.asm(2): Including file 'C:\Archivos de programa\atmel\avr Tools\AvrAssembler2\Appnotes\m168def.inc' F:\EdC\tema4\practicas\solsuma.asm(88): No EEPROM data, deleting C:\Documents and Settings\pdi\Mis documentos\edc\edc.eep ATmega168 memory use summary [bytes]: Segment Begin End Code Data Used Size Use% [.cseg] 0x x00005e % [.dseg] 0x x % [.eseg] 0x x % Assembly complete, 0 errors. 0 warnings list 5. output after assembling the sum program In case of syntax mistakes, the number of the line of the file containing the mistake will be displayed Using the AVR simulator AVR-STUDIO includes a simulator that can be used to watch the processor state during the program execution. It is possible to execute the program instruction by instruction or execute it till reach the desired instruction. To start the program simulation choose the Start Debugging option from the Debug menu. The windows displayed at fig. 5 will appear: Processor window (on the left): It displays information such as cycle counter, frequency and the content of the registers PC, SP, X, Y, Z, SREG as well as the general-purpose registers. I/O window (on the right): It shows every device of the selected microcontroller. Memory window (at the botton): It displays the memory content. You can choose the program memory, SRAM memory and EEPROM memory. We will have to watch the memory content starting at address $100 (we have I/O devices mapped till address $FF).

Computer Structure 7 F Figure 5. AVR-STUDIO debugging utilities The simulator makes it possible to execute the program instruction by instruction.

7 Computer Structure 7 F Figure 5. AVR-STUDIO debugging utilities The simulator makes it possible to execute the program instruction by instruction. The icon is on the left of the next instruction that will be executed. The menu depicted at fig. 6 includes very helpful options to be used during the simulation. When executing step by step, the most used are the following: Step Over: ( ) Execute till the next line. If the current instruction is a subroutine call, the simulation will no stop till the subroutine execution is completed. Step Into: ( ) Execute just one instruction. If the current instruction is a subroutine call, the simulation will stop before executing the first subroutine instruction. Step Out: ( Reset: ( ) Execute till find the next return instruction. ) Reset the simulation. Toogle Breakpoint: ( ) Set a breakpoint on a line. The option Run ( ) will execute the program till the instruction marked with the breakpoint. Run to Cursor: ( ) Execute till reach the instruction under the cursor. Now start the simulation of the execution of the program sum.asm by clicking on Start Debuggin and watch it step by step. To do so can use the F10 key. Check that the program works as expected and do the following: 1. Simulate the program execution using the data sets of table 2 and check the results. 2. Which will be the result if table = {100, 200, 300}?

8 Computer Structure 8 3. Calculate the number of cycles the program will spend (give a formula in the form N + table length Χ M). 4. Simulate the execution of the program order.asm using the same data sets. Table content sum 10, 4, -1, 0, 0, 6, 3, 10, 100, -100, 24, 23, -56, 4, 15, 16 $3A -12, 10, -14, 12, 100, -98, -10, 0, 0, 1, 1, 0, -10, 12, 0, , 90, 80, 70, 60, 50,40,30, 20, 10, Table 2: Data sets to test the program sum Figure 6. Debugging menu 3.2.Developing the program median You must adapt the program order.asm to include it within the list shown bellow. Note that the code includes mistakes that you must correct. To calculate the median, the program must do the following: a) Order the table. b) If the number of elements in the table is odd, the median is the value written in the middle of the table. c) f the number of elements in the table is even, the median is the average of the two central elements..include "m168def.inc".equ tablesize=... //table size.def temp=r16.def Ordered=r17.def NumRep=r18.def Cont=r19.def Median=r20.def a=r1.def b=r2.cseg.org 0 call call initab calculate_median end: jmp end calculate_median:

9 Computer Structure 9 call ldi ldi Order xl,low(table) xh,high(table) ldi Temp,tablesize ror Temp brcc is_even is_odd: adiw xh:xl, (tablesize/2 + 1) ld Median, X ret is_even: adiw xh:xl, (tablesize/2 ) ld Median, X ld Temp,X add Median,Temp ror Median ret Order: /*put here the your subroutine*/... list 6. Program median.asm. 1. Correct the mistakes of the program and check that it works using the data sets of table Write the content of the first 10 program memory locations by generating the.lst file. To do so click on Project -> Assembler Options (fig. 5) and check the option Create List File. You will have to compile the program again. A portion of such a file is shown bellow. Note the pair of hexadecimal numerals on the left of each instruction. The first one is the address of the memory location where the instruction will be stored. The second one is the content of that memory location, i.e. the machine code of the instruction c 920f push r d 930f push temp 00002e 93cf push yl 00002f 93df push yh ef push zl ff push zh e8e4 ldi zl, low(2*tablaeeprom) e0f0 ldi zh, high(2*tablaeeprom) e0c0 ldi yl, low(tabla) e0d1 ldi yh, high(tabla) e100 ldi temp,tamtablaadd

10 Computer Structure 10 Figure 7: Generating the.lst file 3. Which will be the stack content when the processor executes the first instruction of the order subroutine?

Lab 2: Basic Assembly Programming and Debugging using AVR Studio. Due: December 13, 2011

Lab 2: Basic Assembly Programming and Debugging using AVR Studio 1 Outcomes Due: December 13, 2011 Familiarize yourself with the capabilities of the ATMEGA32 embedded microcontroller and AVR Studio Develop