E 332L Microprocessors Lab (Fall 2007) Week 3

Transcription

1 E 332L Microprocessors Lab (Fall 2007) Week 3 Objective: In this lab, you will learn how to interface to LEDs, Seven Segment LEDs, and switches. You will also learn how to write assembly suoutines. Note 1: We are using a different Nios II processor configuration and setup - please follow the following instructions to download the attached FPGA programming file (lab2.sof) and new processor description file (lab2.ptf) for Altera Debug Client Note 2: Do not use the example.sof and system.ptf files from weeks 1 & 2. Note 3: Download lab2.sof and lab2.ptf to your name folder (without spaces in folder name) in D drive. Part 1: Download lab2.sof to Altera DE 2 Double click on Quartus II 7.1 ( ) on the desktop. If the icon is not available, you can access Quartus 7.1 from Start All Programs Altera Quartus II 7.1 Quartus II 7.1 (32-bit). It is time to power-up the DE2 board and connect the USB Blaster cable from the DE2 board to the computer USB port. Now click on the FPGA download button ( ) (should be the third button from the right). You should get the following screen. If you don t, please get help from the lab instructor. Now click on Hardware Setup button, At Currently selected hardware, select USB Blaster [USB-?]. Click Close. The message next to the Hardware Setup button should change from No Hardware to USB-Blaster [USB-?]. Now click on the Add File button, follow the screen to select lab2.sof file you downloaded to D drive. Check the Program/Configure box and click the Start button to program the FPGA. Page 1 of 6

2 Part 2: Generate the Nios II Processor System Description File (system.h) Once you have configured the Altera DE2 board with lab2.sof, start Altera Debug Client using lab2.ptf. At the Nios II System Configure screen, use the following setup: section: Start offset in device 0.data section: Start offset in device 0 Enter the following program (eak.s) using a text editor. The purpose for this program is to cause the Altera Debug Client to produce a file (system.h)for us. Just compiling this program will cause the following file to be created.\app_software\include\. lab2.ptf describes the Nios II processor configuration (the processor features, type, and what devices are available) from a hardware perspective. Using lab2.ptf, Altera Debug Client generates system.h, which is a software perspective of what s in the Nios II processor. The software (in this case, assembly programming language) will know how to interface to the hardware. eak.s # new code goes here : eak Now start a new assembly file with filename lab2_config.s and copy the following into the newly created assembly file. Using system.h, find the device address and complete lab2_config. This file contains the addresses of processor interfaces. It will be used by other assembly programs that you will write for this lab. By including and referencing to this file, you don t have to type these into every program. This means that we have only one location to change if any changes are necessary..equ MEMORY_START,???.equ MEMORY_SIZE,???.equ STACK,MEMORY_START+MEMORY_SIZE.equ LEDS_GREEN,???.equ LEDS_RED,???.equ BUTTONS,???.equ SWITCHES,???.equ SEVEN_SEG,???.equ SYSID,???.equ JTAG_UART,??? Page 2 of 6

3 Part 3: Template File The following is the assembly template file for this lab. # file: lab2_v1.s # author: Your Name # date: 9/8/2007 # this is where your program logic goes : eak Part 4: Suoutines Compare Code 1 and Code 2 below. Note that suoutine modules do not need all of the startup code as the main routine. Observe that values are passed to suoutine via r4 and values are urned via r2. Now, try to send the data from switches to seven segment LEDs. # file: lab2_dev1.s loop: mov SWITCHES_Get r4,r2 LEDR_Set loop_end: loop : eak SWITCHES_Get: ldwio LEDR_Set: stwio Code 1 r3,switches r2,0(r3) r3,leds_red r4,0(r3) Page 3 of 6

4 # file: lab2_dev2.s loop: mov loop_end: : eak Code 2 SWITCHES_Get r4,r2 LEDR_Set loop # file: SWITCHES.s.global SWITCHES_Get SWITCHES_Get: r3,switches ldwio r2,0(r3) # file: LEDR.s.global LEDR_Set LEDR_Set: r3,leds_red stwio r4,0(r3) You are to learn how suoutines work from Code 1 and Code 2. What the main differences between Code 1 and Code 2? Once you have done so, you need to create a new assembly suoutine to interface to the green LEDs and tie in to the main assembly program. Run and observe Code 3. sp,stack /* Setup the stack and frame pointer */ mov fp,sp /* registers. */ movi r4,6 lab2_sum_init loop: beq addi loop_end: r4,r0,loop_end lab2_sum_add r4,r4,-1 loop : eak lab2_sum_get Code 3: lab2_main.s Page 4 of 6

5 .global lab2_sum_init lab2_sum_init: r2,lab2_sum stw r0,0(r2).global lab2_sum_add lab2_sum_add: r2,lab2_sum ldw r3,0(r2) add r3,r3,r4 stw r3,0(r2).global lab2_sum_get lab2_sum_get: r2,lab2_sum ldw r2,0(r2).data lab2_sum:.word 0 Code 3: lab2_sub.s Think about lab2_sum variable and the scope of access (can lab2_sum modifiable directly from lab2_main.s?). Part 5: Macros Insert the given assembly code into the template in Part 3. This assembly programs sets up a 32-bit number using the instruction. The next two instructions shift the 32-bit register and mask with 0b1111 (same as 0xf). This gets 4-bit ( 6 ) out of the 32-bit number. r4,0x srli r2, r4, 8 andi r2, r2, 0b1111 The following assembly code sets up a 32-bit number using insruction again, then replace 6 with b. movi r2,0x r4,0xab andi r4, r4, 0b1111 slli r4, r4, 8 movi r3, 0b1111 slli r3, r3, 8 nor r3, zero, r3 and r2, r2, r3 or r2, r2, r4 Now copy the following assembly code into the template again. Run and observe. Now get and replace different bits. The macros needed to be inserted before the directive in the template. Page 5 of 6

6 .macro getbits rego, regi, offset, mask srli \rego, \regi, \offset andi \rego, \rego, \mask m.macro putbits rego, regi, regw, offset,mask andi \regi, \regi, \mask slli \regi,\regi,\offset movi \regw,\mask slli \regw, \regw, \offset nor \regw, zero, \regw and \rego,\rego,\regw or \rego,\rego,\regi m r4,0x getbits r2,r4,8,0xf movi r3,0xa putbits r4,r3,r5,8,0xf Assignment Due (11:59:59 pm of September 17, 2007): Create a new assembly file (using filename mymacros.s) and copy the previous two macros into this newly created file. Your job is to create three other macros: increment, decrement, and divide with remainder (for divide with remainder, the result should be in r2 and remainder in r3). Hint: for divide and remainder, refer to Nios II Processor Reference Handbook The macro templates are:.macro incr reg,.macro decr reg, and.macro divr number, divisor Note: number and divisor are registers Page 6 of 6