Figure 1. Software interface generated by Nios IDE - 1 -

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Frederick August Green
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1 ECE 332L Microprocessors Lab (Fall 2007) Lab 6 Continue (Week 9) Objective: In this lab, you will continue the exploration of interrupts in C using a portion of the Hardware Abstraction Layer (HAL) support from Altera. Note: Use ptf and sof from last week Part 1: Interrupt Service Routine with Assembly only Last week we worked with the modules int1.s, int2.s, int3.s, and int4.s. You were told to use (Quartus II Version 7.1 Handbook Volume5: Embedded Peripherals) JTAG UART (Chapter 7: JTAG UART Core with Avalon Interface) to create int5.s that when values are typed into the Terminal Window cause an interrupt to happen. The value received from keyboard is displayed to the seven-segment LEDs. The ISR should store the character value received into a variable that is retrieved from the main routine. Look at the steps taken in examples int3.s and int4.s and compare to the documentation for those devices. Using this knowledge review the documentation for the JTAG UART to produce code that will achieve the desire results. Part 2: Interrupt Service Routine with C Programming Language and Minimum HAL Last week we interfaced to interrupts from the assembler language platform. This week we will interface from the C platform provided by Altera. When the NIOS II IDE creates the system library (syslib, figure 1 is a block diagram of a portion of the initialization process and interfaces provided by Altera) it automatically creates lowlevel drivers and interfaces for key devices such as the timer and JTAG UART devices. For this lab we wish to implement these low-level control ourselves (Trust me, this is what you will have to do in real world. So, sit tight and learn this stuff.). In order to do this we must disable the interfaces provided by Altera. main () alt_main () alt_sys_init() Altera HAL API 2 init TIMER init JTAG_UART init SP_SPI init LCD init UART init SYSID crt0.s 1 Altera HAL TIMER JTAG_UART SD_SPI LCD UART SYSID 0x20 Hardware Figure 1. Software interface generated by Nios IDE - 1 -

2 In order to disable the devices for this lab navigate to the syslib directory in the NIOS II IDE directory for you project and find the alt_sys_init.c file and comment out the two lines shown in Figure 2. After the syslib has been re-compiled the block diagram of the system should be as shown in Figure void alt_sys_init( void ) // ALTERA_AVALON_TIMER_INIT( TIMER, timer ); // ALTERA_AVALON_JTAG_UART_INIT( JTAG_UART, jtag_uart ); ALTERA_AVALON_SPI_INIT( SD_SPI, sd_spi ); ALTERA_AVALON_LCD_16207_INIT( LCD, lcd ); ALTERA_AVALON_UART_INIT( UART, uart ); ALTERA_AVALON_SYSID_INIT( SYSID, sysid );... Figure 2. Disable low-level support for timer and jtag_uart main () Timer_Init ( ); JTAG_UART_Init (); 3 4 alt_main () alt_sys_init() Altera HAL API 2 init SP_SPI init LCD init UART init SYSID 1 TIMER JTAG_UART Figure 3 Altera HAL SD_SPI LCD UART SYSID Hardware Figure 3: Software interface generated by Nios IDE after modification - 2 -

3 Once Altera is no longer controlling these devices we are ready to start developing our own code to control them ourselves. You are provided with four modules as examples for working with ISR code in this environment. Code examples in3.c - prototype code for buttons ISR in4.c - prototype code for timer ISR in5.c - prototype code for JTAG UART ISR in6.c - Typical layered driver model for buttons and timer ISRs Even though we have removed these devices from Altera s HAL environment we will still utilize functionality for dealing with ISR s provided by Altera. In your reference manuals find documentation for the following HAL API Functions. alt_irq_disable () alt_irq_enable () alt_irq_register () alt_irq_diable_all () alt_irq_enable_all () alt_irq_enabled () Now load and run the example code Setup project int3.c (same functionality as int3.s) buttons interrupts in C. Compare the int3.s solution. Setup project int4.c (same functionality as int4.s) timer interrupts in C. Compare the int4.s solution. Setup project int5.c (same functionality as int5.s) jtag_uart interrupts in C. Build the project but do not run from Nios IDE. This routine will require testing in a different manor. Since we have disabled the JTAG UART routines in Nios IDE we cannot interact with the solution in FPGA through the console. So we will test another way. Open two NIOS II 7.1 Command Shells In the first shell issue the following nios2-terminal In the other navigate to the directory that contains int5.elf then issue the following command nios2- download g int5.elf Now go back to 1st window and start typing characters. You should see results on seven-segment LEDs of DE

4 // int3.c Button interrupts #include "sys/alt_irq.h" #include "unistd.h" // for usleep typedef unsigned int REGISTER; struct PIO_REGS REGISTER direction; REGISTER intmask; REGISTER edgecapture; ; // data register // direction register // interrupt mask register // edge capture register struct PIO_REGS *LEDS_RED = (struct PIO_REGS *)(LEDR_BASE 0x ); struct PIO_REGS *BUTTONS = (struct PIO_REGS *)(BUTTONS_BASE 0x ); static unsigned int BTNS = 0; void handle_button_interrupts() BTNS = BUTTONS->edgecapture; // get buttons pushed BUTTONS->edgecapture = 0; // acknowledge interrupt handled int main (void) REGISTER LAST_BTNS; // save last buttons pushed alt_irq_register( BUTTONS_IRQ, NULL, (void*)handle_button_interrupts ); BUTTONS->intmask = 0x5; // 0b101 while (1) if ( BTNS!= LAST_BTNS ) // have buttons changed LEDS_RED->data = BTNS; // show buttons LAST_BTNS = BTNS; // get new buttons benchmark usleep(100); return 0; - 4 -

5 // int4.c timer interrupts #include "sys/alt_irq.h" #include "unistd.h" // for usleep typedef unsigned int REGISTER; typedef unsigned int BITS; struct PIO_REGS REGISTER direction; REGISTER intmask; REGISTER edgecapture; ; // data register // direction register // interrupt mask register // edge capture register union TIMER_STATUS_REG struct BITS TO : 1; BITS RUN : 1; BITS unused : 30; bits; ; union TIMER_CONTROL_REG struct BITS ITO : 1; BITS CONT : 1; BITS START : 1; BITS STOP : 1; BITS unused : 28; bits; ; struct TIMER_REGS union TIMER_STATUS_REG status; union TIMER_CONTROL_REG control; REGISTER periodl; REGISTER periodh; REGISTER snapl; REGISTER snaph; ; struct PIO_REGS *SEVEN_SEG = (struct PIO_REGS *)(SEVENSEG_LED_BASE 0x ); struct TIMER_REGS *TIMER = (struct TIMER_REGS *)(TIMER_BASE 0x ); static unsigned int SYSTIME = 0; void handle_timer_interrupts() SYSTIME++; TIMER->status.bits.TO = 0; int main (void) REGISTER LAST_TIME; // acknowledge interrupt handled // save last time value alt_irq_register( TIMER_IRQ, NULL, (void*)handle_timer_interrupts ); TIMER->control.bits.ITO = 1; // activate timer interrupts while (1) if ( SYSTIME!= LAST_TIME ) // has time changed SEVEN_SEG->data = SYSTIME; // show count in hex LAST_TIME = SYSTIME; // get new time benchmark return 0; - 5 -

6 // int5.c JTAG UART Interrupts #include "sys/alt_irq.h" #include "unistd.h" // for usleep typedef unsigned int REGISTER; typedef unsigned int BITS; struct PIO_REGS REGISTER direction; REGISTER intmask; REGISTER edgecapture; ; // data register // direction register // interrupt mask register // edge capture register union JTAG_UART_DATA_REG struct BITS data : 8; BITS unused : 7; BITS rvalid : 1; BITS ravail : 16; bits; ; union JTAG_UART_CONTROL_REG struct BITS RE : 1; BITS WE : 1; BITS fill_1 : 6; BITS RI : 1; BITS WI : 1; BITS AC : 1; BITS fill_2 : 5; BITS wspace : 16; bits; ; struct JTAG_UART_REGS union JTAG_UART_DATA_REG data; union JTAG_UART_CONTROL_REG control; ; struct PIO_REGS *SEVEN_SEG = (struct PIO_REGS *)(SEVENSEG_LED_BASE 0x ); struct JTAG_UART_REGS *JUART = (struct JTAG_UART_REGS *)(JTAG_UART_BASE 0x ); static unsigned char THE_CHAR = 0; void handle_jtag_uart_interrupts() THE_CHAR = JUART->data.bits.data; int main (void) unsigned char LAST_CHAR = 0; // save last character entered alt_irq_register( JTAG_UART_IRQ, NULL, (void*)handle_jtag_uart_interrupts ); JUART->control.data = 0; JUART->control.bits.RE = 1; while (1) if ( THE_CHAR!= LAST_CHAR ) // has character changed? SEVEN_SEG->data = (REGISTER)THE_CHAR; // show character LAST_CHAR = THE_CHAR; // get new character benchmark return 0; - 6 -

7 In the previous three C interrupt examples, it is specialize to just one device ISR. What do you do when you have to service multiple devices? Following is an implementation in C of the generalize solution presented in part 2. Take the source code files provided (in int6 folder) and observe the behavior. This is a good base for you assignment. main.c #include "timer.h" #include "buttons.h" #include "seg7.h" #include "ledr.h" int main (void) unsigned int LAST_TIME; unsigned int LAST_BTNS; // save last time value timer_init(); buttons_init(); // initialise timer ISR // initialise buttons ISR while (1) if ( SYSTIME!= LAST_TIME ) // has time changed seg7_show(systime); // show count in hex LAST_TIME = SYSTIME; // get new time benchmark if ( BTNS!= LAST_BTNS ) LEDR_show(BTNS); LAST_BTNS = BTNS; return 0; // have buttons changed // show buttons // get new buttons benchmark timer.h #ifndef TIMER_H_ #define TIMER_H_ void timer_init(void); extern unsigned int SYSTIME; #endif /*TIMER_H_*/ buttons.h #ifndef BUTTONS_H_ #define BUTTONS_H_ void buttons_init(void); extern unsigned int BTNS; #endif /*BUTTONS_H_*/ - 7 -

8 timer.c // timer.c #include "sys/alt_irq.h" #include "unistd.h" // for usleep #include "timer.h" #include "timer_regs.h" static void handle_timer_interrupts(); // handler is private static struct TIMER_REGS *TIMER = (struct TIMER_REGS *)(TIMER_BASE 0x ); unsigned int SYSTIME = 0; // also defined as extern void timer_init(void) alt_irq_register( TIMER_IRQ, NULL, (void*)handle_timer_interrupts ); TIMER->control.bits.ITO = 1; static void handle_timer_interrupts() SYSTIME++; TIMER->status.bits.TO = 0; // acknowledge interrupt handled buttons.c // buttons.c #include "sys/alt_irq.h" #include "unistd.h" // for usleep #include "buttons.h" #include "pio_regs.h" static void handle_button_interrupts(); // handler is private struct PIO_REGS *BUTTONS = (struct PIO_REGS *)(BUTTONS_BASE 0x ); unsigned int BTNS = 0; // also defined as extern void buttons_init(void) alt_irq_register( BUTTONS_IRQ, NULL, (void*)handle_button_interrupts ); BUTTONS->intmask = 0x5; // 0b101 static void handle_button_interrupts() BTNS = BUTTONS->edgecapture; // get buttons pushed BUTTONS->edgecapture = 0; // acknowledge interrupt handled - 8 -

9 ledr.c // ledr.c #include "ledr.h" #include "pio_regs.h" static struct PIO_REGS *LEDR = (struct PIO_REGS *)(LEDR_BASE 0x ); void LEDR_show(unsigned int val) LEDR->data = val; seg7.c // seg7.c #include "seg7.h" #include "pio_regs.h" static struct PIO_REGS *SEVEN_SEG = (struct PIO_REGS *)(SEVENSEG_LED_BASE 0x ); void seg7_show(unsigned int val) SEVEN_SEG->data = val; ledr.h #ifndef LEDR_H_ #define LEDR_H_ void LEDR_show(unsigned int val); #endif /*LEDR_H_*/ seg7.h #ifndef SEG7_H_ #define SEG7_H_ void seg7_show(unsigned int val); #endif /*SEG7_H_*/ Assignment - Clock Timer Create a routine that utilizes the LCD display to show the time (HRS:MIN:SEC:1/10SEC) on one line (2nd line) and a greetings message on the 1st line (e.g. Good Day! or days until next ECE 332L assignment!). The greetings message and initial time (you pick one) should have default values but you need to be able to update them from values taken from the JTAG UART interface. Input for the greetings message and initial time should be taken from the JTAG UART (stdin). Hint: scanf function. Note that updating the time while the Timer ISR is operational presents the possibility for a race condition. One way to avoid this is to disable the Timer ISR during the time when the time value is being updated. Other things to consider: 1. What internal variable type should be used hold the time value? Where is the limiting factor for your choice (internal value or display)? Justify your choice. 2. Where should the conversion to (HRS:MIN:SEC:1/10SEC) be done? In the ISR or in the display update routine? - 9 -

10 Grading considerations: 1. Does it work as specified or negotiated? (80%) 2. Style or organization. (10%) 3. Code documentation (no report, required a readme file explaining features and how to run it) (10%) For this assignment, you only need to comment out the timer as the following.... void alt_sys_init( void ) // ALTERA_AVALON_TIMER_INIT( TIMER, timer ); ALTERA_AVALON_JTAG_UART_INIT( JTAG_UART, jtag_uart ); ALTERA_AVALON_SPI_INIT( SD_SPI, sd_spi ); ALTERA_AVALON_LCD_16207_INIT( LCD, lcd ); ALTERA_AVALON_UART_INIT( UART, uart ); ALTERA_AVALON_SYSID_INIT( SYSID, sysid );... Figure 4. Disable low-level support for timer (for assignment)

Engineering Design Lab exercise 2 Nios II Processor Software Development

Engineering Design Lab exercise 2 Nios II Processor Software Development Note: To do this lab exercise you need the textbook and it s CD. Part 1 Designing systems with embedded processors requires both