Laboratory instructions
Contents
1. before the lab session e have answered all questions of Section 2 e have completed all laboratory tasks of Section 3 and answered all questions from Teachers Name of Student 0 00 c cece cece cceescceeeeeeccceeeuneeseseeeeuas O Laboratory exercise 1 completed signed by Teacher s cee eeeeee eee nee e ees References Alt Intro Altera Corporation Introduction to the Altera Nios II Soft Processor Alt HW Altera Corporation Nios IT Processor Reference Handbook Alt SW Altera Corporation Nios IT Software Developer s Handbook Alt I O Altera Corporation Nios IT Embedded Peripherals Handbook Alt DE2 Altera Corporation DE2 Development and Education Board User Manual NextPrime C code In the main loop call NextPrime as follows next NextPrime next Produce a new prime printf nNext Prime is d next The NextPrime function itself NextPrime Return the first prime number larger than the integer given as a parameter The integer must be positive 7 define PRIME_FALSE 0 Constant to help readability define PRIME_TRUE 1 Constant to help readability int NextPrime int inval int perhapsprime Holds a tentative prime while we check it i int testfactor Holds various factors for which we test perhapsprime int found Flag2. called only once per second Modify your program so that the pollkey function is called once per millisecond Make sure that the time still will be incremented only once per second 2 9 Timing by use of hardware timer and HAL functions Most processors offer possibilities to use hardware timer circuits As the timer circuits are clocked by a crystal oscillator the accuracy is in the order of 1 per million or even better In the Nios II processor several timers are available Update your program to use a timer instead of using programmed delay It is possible to order a timer to alarm at some time in the future HAL functions are supported to handle alarms of this kind The idea is that when the alarm expires a special function alarm handler is called and executed This function the alarm handler shall perform the actions wished print time value and might also order if and when the same function shall be called again This is sometimes named call back Create a new project called 1ab1timer and copy all files from the previous project to the new project Modify the new project to use HAL functions to order alarm once per second to print actual time on terminal and hex display In the mainloop of the program still continue to poll the keys to keep the behaviour of the buttons You must write the alarm handler function and use the HAL function to initiate the system to use it Information of thes
3. will work on the DE2 board at the lab session To be able to run the NextPrime function in the NiosII Instruction Set Simulator right click on the project folder choose System Library Properties check the box Emulate multiply and divide instructions click Apply If you forget to do this the simulator may give an error message like Break instruction called without debugger attached 2 12 Configuration In order to study the configuration used for the DE2 board open the system h file Answer the following questions 1 Which Nios processor is used in this configuration Give the number of stages in the processor pipeline 2 The configuration contains a number of different memories Order these memories after typical access times and give the size of each memory 3 Which I O devices and timer devices are used in the tasks of Section 2 Give their address spaces and IRQ levels 3 Laboratory tasks performed at the laboratory session 3 1 C and Assembler Show time in the console window You must have passed Laboration 0 Bring up your program from Laboration 0 Run your program from Laboration 0 on the Nios II Hardware When you connect the DE2 board with a USB cable to your laptop computer you may need to install a USB driver This is described in Getting Started with Altera s DE2 Board Answer all questions from the teacher O C code Show Time completed signed by Teacher 0 202 i cjisarsteade
4. GD we o KTH X VETENSKAP H G9 OCH KONST A eol KTH Information and Communication Technology IL2206 2B1446 Embedded Systems Laboratory 1 Input Output and Interrupts in Nios H Systems 24 augusti 2009 Updated version 24 augusti 2009 New information Write the pollkey function in the same file as the timeloc variable and the main program 1 Objectives This laboratory will help you to e get used to the hardware and software of the laboratory environment e deepen your understanding of how C and Assembler functions interact e deepen your understanding of I O handling with polling and interrupt e access embedded peripherals by means of C Macros and the HAL System Library e get used to the Altera documentation 2 Preparation Tasks Read the entire laboratory manual in detail before you start with the preparation tasks Complete the preparation tasks before your lab session in order to be allowed to start the laboratory exercises It is very important that students are well prepared for the labs Lab rooms B35 and B36 and laboratory teachers are expensive and limited resources which must be used efficiently Please claim your seat in time After a specified time such as 20 minutes laboratory teachers may re allocate unused seats to other students including students who have been unable to book a seat For admission nearly all preparation tasks must be finished and some tasks are strictly required fo
5. code to 7 bit seven segment code The four least significant bits of the input value are to be converted into a 7 bit value such that this value can be sent directly to a seven segment display to produce the appropriate digit in a C function Recommended digit patterns are shown in the Figure below To light up a segment of a seven segment display digit the corresponding bit should be zero 0 A one 1 will shut the segment off bit index a Mo SL erent 5 6 LU Af el 0 UL OL Ev JL IL a Jak 2 6 The puthex function Write a C function puthex with the following prototype void puthex int inval The purpose of the function is to display the current time on the seven segment digits HEX3 through HEXO The puthex function should call bcd27seg Add a call to the puthex function in your C coded main loop The call to puthex function will be tested on the lab occasion not in the simulator 2 7 Parallel Input Output polling Input using macros The pollkey function In the text above you can find which macro to use when you want to read values from KEY3 KEY0 Create a new project called lab1IO and copy all files from the previous project to this new project Add a call to a pollkey function see below in your C coded main loop Write the C code of the function pollkey in the same file as the timeloc variable and the mainprogram This makes i
6. e macros can be found in Software Developer s Handbook in the starting pages of chapter 5 Developing Programs Using the HAL Using Timer Devices 2 10 T O Interrupt using HAL functions Refresh your memory concerning how to use interrupts in software and hardware especially in the Nios II CPU Find out which HAL functions to use to initiate and register interrupts in Nios IL Information on HAL functions can be found in Software Developer s Handbook chapter 7 Exception Handling In the previous program most of the CPU time is spent polling the keys to detect changes Most of the CPU time no changes occur and valuable CPU time is wasted It might be smarter to let the CPU work with something valuable in this lab exercise calculating primes instead of waiting for buttons to change The buttons have hardware support for interrupts Information on this can be found in the Nios II Embedded Peripherals Handbook chapter 11 PIO Core with Avalon Interface Create a new project called 1ablint and copy all files from the previous project to the new project Modify the programs in your new project to use interrupt from the keys instead of polling the keys The main loop will now do nothing idle loop This means that you must write a Key_InterruptHand1ler for the Button PIO and that you must initialize the system so that interrupts from the Button PIO will cause the Key_Interrupt_Handler function to be executed You must al
7. ececedueuseuced 3 2 Parallel I O Output on the LED and on the HEX display Run your program from Section 2 4 on the Nios board in the laboratory Answer all questions from the teacher O Parallel 1 0 Output completed signed by Teacher i c05sciceceudesdaseceeeeevesvese 3 3 Parallel I O Input from the keys affecting the time value Run your programs from Section 2 7 and 2 8 on the Nios board in the laboratory Show the flow chart description of the pollkey function Answer all questions from the teacher O Parallel 1 0 Input completed signed by Teacher o 2 0s0ccscdveauevessseecssesexd ees 3 4 Callback using Timer Run your program from Section 2 9 on the Nios board in the laboratory environment Answer all questions from the teacher O Callback using Timer completed signed by Teacher 1 ccccusccsencvesecsveewnsvnsen scouts 3 5 Interrupt generated by Keys using HAL functions and Primes Run your program from Section 2 11 on the Nios board in the laboratory environment Answer all questions from the teacher O Interrupt using HAL functions signed by Teacher sceeeeeeneeeeeeee 3 6 Surprise modification given by teacher O Surprise work to do decided by Teacher e cece cece eee eeee eens O Surprise work completed signed by Teacher cece eee eee eee e eens 4 Examination In order to pass the laboratory the student must e have completed all preparation tasks of Section 2
8. ern void tick int timeloc extern void delay int millisec extern int hexasc int invalue define TRUE 1 int timeloc 0x5957 startvalue given in hexadecimal BCD code int main while TRUE puttime amp timeloc tick amp timeloc delay 1000 return 0 2 4 Parallel Input Output Output using macros W Software accesses the hardware such as I O ports on the DE2 board using macros that hide the memory mapped low level interface to the device Information about these macros can be found in Software Developer s Handbook at the starting pages of chapter 6 Developing Device Drivers for the HAL In order to write to a parallel I O port use the macro TOWR_ALTERA_AVALON_PIO_DATA Example code The command IOWR_ALTERA AVALON PIO DATA DE2_P O_REDLED18_BASE Ox3fffF writes 1 s to all 18 red leds and thus turns on all LEDs In order to read from a parallel I O port use the macro TORD_ALTERA_AVALON_PIO_DATA Example code The command TORD_ALTERA_AVALON_PIO_DATA DE2_PTO_KEYS4_BASBE returns state of the buttons as an integer bit pattern a 0 means that the corresponding button is pressed Symbolic names of I O ports and I O registers can be found in the system h file The system h file is generated when the system library is built and compiled You can find the system h file in your projects It is s
9. false until we find a prime if inval lt 3 Initial sanity check of parameter if inval lt 0 return 1 Return 1 for zero or negative input if inval 1 return 2 Easy special case if inval 2 return 3 Easy special case else Testing an even number for primeness is pointless since all even numbers are divisible by 2 Therefore we make sur that perhapsprime is larger than the parameter and odd perhapsprime inval 1 1 While prime not found loop for found PRIME_FALSE found PRIME_TRUE perhapsprime 2 Check factors from 3 up to perhapsprime 2 for testfactor 3 testfactor lt perhapsprime gt gt 1 testfactor 1 found PRIME_TRUE Assume we will find a prime if perhapsprime testfactor 0 If testfactor divides perhapsprime found PRIME_FALSE then perhapsprime was non prime goto check_next_prime Break the inner loop go test a new perhapsprime check_next_prime This label is used to break the inner loop if found PRIM FE TRU ry return perhapsprime return perhapsprime i i Return the prime we found If the loop ended normally we found a prime R When the loop ends perhapsprime is a real prime 10 Bf
10. ituated in the system library in folder Debug gt system_description gt system h You have to include some files in your program if you are using macros and or symbolic names of IO ports for instance include system h include altera_avalon_pio_regs h Symbolic names used in our CPU configuration are e DE2_PIO_REDLED18_BASE for the eighteen LEDRs LEDR17 is MSB Bit 17 and LEDRO LSB Bit0 e DE2_PIO_GREENLED9_BASE for the nine LEDRs LEDG8 is MSB Bit 8 and LEDGO LSB Bit0 e DE2_PIO_KEYS4_BASE for the four buttons KEY3 is MSB Bit 3 and KEYO LSB Bit 1 e DE2_PIO_HEX_LOW28_BASE for the seven segment displays The seven segment display has four digits The leftmost digit is controlled by the seven most significant bits HEX3 bits 27 through 21 the left middle digit is controlled by the next seven bits HEX2 bits 20 through 14 then follows the right middle digit HEX1 bits 13 through 7 and the rightmost digit by the least significant bits HEXO bits 6 through 0 Update the main loop in your program and include a macro that will cause the time value to be written in binary form on the 16 red LED s LEDR15 through LEDROO Use the natural BCD encoding with four groups of four bits each 2 5 The bced27seg function Write a C function bcd27seg with the following prototype int bcd2seven int inval The purpose of the function is to convert 4 bit binary
11. nd Education Board Use your programs and your experience from laboratory exercise 0 and upgrade your programs as a preparation for this laboratory exercise O Lab 0 completed 2 3 Show Time program written in C and Assembler Strictly required preparation task Use programs that are written and simulated in Laboratory exercise 0 The C function void puttime int timeloc reads the time value stored at memory address given by the pointer parameter timeloc and prints it to a terminal window The printout must be in the format 42 33 and must be printed to the left on a new line The C function void tick int timeloc increments by one the time value stored at memory address given by the pointer parameter timeloc The Nios II assembly subroutine delay int millisec will delay program execution by the number of milliseconds given by the parameter millisec The Nios II assembler subroutine hexasc transforms one 4 bit BCD coded value in the range O through 9 inclusive and returns its correspondning ASCII code This subroutine is called from the C code within the C function putt ime Create a new project called lab1 and copy all programs from lab 0 to the new project Replace the main program written in assembly code with the C code given below When executing the main program given in the C code below each second the actual time is printed to the console window include lt stdio h gt extern void puttime int timeloc ext
12. on Binary Interface and Instruction Set Currently chapters 7 and 8 of Alt HW Especially parameter passing and size of datatypes Detailed information of each instruction e Hardware Abstraction Layer and HAL system library Currently chapters 2 5 6 8 and 14 of Alt SW Here you can find out which macros to use reading and writing registers in I O circuits PIO and Timer You can also find information of how to use HAL functions to initiate and use interrupts e Nios II Assembler and Application Binary Interface Currently chapters 9 and 24 Alt IO Especially I O register organization and use in PIO and Timer Details of the Cyclone II FPGA board that is used in this laboratory is described in the e DE2 Development and Education Board User Manual Alt DE2 You should also have a look on the project templates that are available when you create a new application in the Nios II IDE Valuable information can also be found in the lecture notes pointed to from the course homepage Oai completed 2 2 Lab Access and Account You will perform the lab on your own notebook computer After you have been registered for the course in the KTH study system Ladok make sure that you can log on to the KTH wireless network There will be no spare computers in the course laboratory 2 O 22 completed 2 3 Laboratory exercise 0 In laboratory exercise 0 you have developed and tested a program and also run it on the DE2 Development a
13. r admission The laboratory work will be performed by groups of two students However each student must understand all developed source code and all preparation tasks HAL Hardware Abstraction Layer Course assistants will check that students are well prepared When preparing for the laboratory work Whenever you have completed a preparation task of the laboratory mark the preparation task as completed by putting a cross into the corresponding circle At the lab session Whenever you have completed a laboratory task show it to the teacher and answer all questions about your program The teacher will mark the laboratory task as completed by writing a signature on the corresponding dotted line 2 1 Literature studies In order to solve the preparation tasks a lot of information can be found in the Altera documentation on Nios II Alt HW Alt SW Alt IO pointed to by the course homepage The student is encouraged to get a good overview of the Altera documentation and to be able to make use of it Often the given references provide example code for instance how to program the timer to generate alarm and program the input keys to generate interrupt The main focus of the reading should be on the following e Introduction to the Altera Nios II Soft Processor Alt Intro Read this thoroughly it is a very good introduction e Nios II processor and programming model Currently chapters 2 and 3 of Alt HW e Nios II Applicati
14. so enable interrupts from the Button PIO by writing appropriate value s to the appropriate register s in the Button PIO using the appropriate macro s Information of suitable HAL functions can be found in Nios II Software Developer s Handbook chapter 7 Exception Handling The behavior depending on how you push the buttons must be changed a little from the previous exercises e KEYO Each time you push the button KEYO the time shall START or STOP counting e KEY1 Each time you push the button KEY1 the time value presented must be incremented by one KEY 2 Each time you push the button KEY2 the the time value must be set to 00 00 KEY3 Each time you push the button KEY3 the the time value must be set to 59 57 2 11 I O Valuable background work calculating primes At the last page of these instructions you will find the function NextPrime Its prototype is int NextPrime int inval This function will return the smallest prime number bigger than inval Calling NextPrime with a value of 17 in inval will return the value 19 since this is the next larger prime Calling with the value 26 will return the value 29 and so on Update your program in previous project so that Prime Numbers are calculated by the background program loop and printed on the console window at the same time as time is shown on the HEX displays and LEDR s Make sure that time can still be manipulated by the Keys as specified above The function NextPrime
15. t possible for the pollkey function to reference the timeloc variable Write a C function pollkey with the following prototype void pollkey that polls the keys and affect the behaviour of the time presentation Each time you push a button the behavior must change It is OK that your program expects you to release the button before you push another or the same button and that you never push two buttons at the same time It is out of the scope of this lab to take care of all possibilities but you are allowed to do it e KEYO Each time you push the button KEYO the time must START counting e KEY1 Each time you push the button KEY1 the time must STOP counting e KEY2 Each time you push the button KEY2 the time value presented must be incremented by one second e KEY3 Each time you push the button KEY3 the time value must be set to 00 00 You must use a flow chart as shown in the recitations and in lab 0 to describe the behavior of the pollkey function You can find sample flow charts in the exercise material and in the laboratory exercise 0 delay is described by a flow chart Hints You can use a variable RUN to indicate if the counting is ON or OFF and use this variable to decide if tick is going to be called or not 2 8 Response time If you run the program above you will find that the response time when you push a button might be disturbingly long Probably also some button pushes are lost because the pollkey function is
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