EE 476: Laboratory 1

Introduction to the lab hardware/software.

Introduction.

This assignment introduces you to the software and hardware development tools you will use this semester to work with the Atmel AT90-series microcontroller chips.

Hardware

The hardware you will be using to support the AT90-series is the Flash MCU evaluation board, a small board providing:

• A target AT90-series microcontroller (mcu) with onboard flash program memory.
• A programmer for the target flash memory, including a parallel connection to a PC.
• Eight general pushbuttons, eight LEDs and a RESET button.
• A serial connection for applications.
• Connectors for bringing out the microcontroller signals to user-designed peripheral equipment. Note that there is no protection on these lines. You are connecting directly to the mcu. Prudent design suggests you might want to use buffers when you are uncertain of voltage levels or other conditions. The pin definitions for the connectors are shown below. The inner squares represent pins. The outer border is a white line surrounding the plug.

  

A small power supply provides power to the development board.

Most lab exercises will involve using a prototype board. A separate power supply will be used for powering the prototype board.

Software

Software you will use consists of:

• The AVR assembler which takes assembler source code and produces an object file, a hex file and a listing file.
• AVR Studio which simulates the execution of an object file.
• AvrProg which downloads the hex file to the target mcu.
• A locally written keyboard monitor program.
• A couple of weeks from now, we will be using the CodeVisionC C complier.

1. Make sure the evaluation board is connected to power and to the PC as specified in the evaluation board description. Turn on the power supply with the switch on the board. A red LED in the middle of the board should turn on. For this first lab, there should be jumpers on the PortB to the LED header and on PortD to the switch header. Ask your instructor for help if these are not installed.

2. Make a subdirectory for your group in the c:\users directory. Be sure to put all your files there and to back up daily to floppy. Random user files found outside the c:\users directory may be erased.

3. The software you will use can be found in the Start menu under AVR Tools.

4. You can use the AVR assembler source-editor window to construct a text file of assembler code. For now, paste this source code into the editor window. Be sure that you have placed the 8515def.inc header information in your directory and modify the include line in the assembler source so that the assembler can find it.

5. Click on the assemble button on the assembler menu. A message window will open to tell you if there are errors in the code. If there are errors, The open the listing file to see where they are.

6. Open AvrISP. Load the hex file you have just produced with the assembler, then click the "Program Flash" muen item. The code should download and start to run. This demo program should cause the LEDs to count up at 10 per second.

As a demo of the keyboard monitor download this code and the keyboard monitor then experiment with uncommenting the two incidated lines of code and experiment with the keyboard commands. Try reading the count register, reading PORTB, and single-stepping the program.

All timing must be done with interrupt-driven hardware timers and not with software wait-loops. Each of the following modifications should be saved separately for demonstration. For this lab, all programs must be in assembly language.

1. Modify the program you were given to count up at one count per second only when switch0 is pressed and held. The LED displayed count should stop counting when the switch is not pressed.

2. Modify the program to cause the LEDs 0-6 to count up in binary from 0x00 to 0x07F and back down to 0x00 again, and repeat indefinitely. The count rate should be 10 per second. Also, LED 7 should blink at a rate of one per second.

Your written lab report should include:

• How accurate was the interrupt time base in the program you were given? How could you make it more accurate?
• Why did we make you use interrupts rather than wait-loops?
• The listings of your programs.