Getting your computer (and you) set up

• Download and install WinAVR

• Skim the installation and configuration manual

• Skim the AVR ISP Userguide (first 3 chapters)

• Skim the AVRDude Userguide

• Skim the AVR Lib Manual. You may find the AVR Lib Manual in PDF more useful.

• If you don't have a DB-9 serial port on your computer, you will need to use the USB adapter. You will need to download and unpack the drivers for this (and then see the discussion on the discussion board).

For the linux folks

• avr-gcc

• avrlib

• avrdude (you may have to download the source and compile this one yourself)

Creating and compiling your program

• Create your C program (start with this sample program: led_flash.c). You may use the Programmer's Notepad from WinAVR if you wish (but it is not necessary)

• Create a makefile (start with this sample makefile)

• Modify the makefile so that it points to your source file:
  Change the TARGET = led_flash.c line so that it contains the name of your source file.

• Compile the your program:
  • From the windoze menu, select: "run" and then type "cmd"

  • Use the "cd" command to change directory to the location of your makefile and source file.

  • Type make. If there are no errors in your program, you will have a variety of files, including:
    • led_flash.lst: a file that shows both your program and the corresponding assembly code
    • led_flash.hex: a file that contains the program information that will be downloaded to your processor

A Basic Circuit

You may use the original led_flash2.fig file if you wish (this is an xfig file).

The key components are:

• The Atmel Mega8: your microcontroller. Note the power and ground connections.
• The AVR ISP Connector: connects the processor to the programmer.
• L1 and L2: LEDs used in the sample program. Note that the polarity of the LEDs is critical. Also - you need a resistor in series with each of the LEDs (200 ohms will do).
• LC is a status LED that allows you to see when the programmer is downloading code to your processor. This LED is useful, but not necessary.
• The crystal and 15 pF capacitors connected to pins 9 and 10 are necessary if you want your processor to be clocked at 16 MHz (by default the processors use an internal clock that runs at 1 MHz).
• The 10K ohm resistor on the reset line (pin 1) keeps the line high so that the processor will not reset (unless commanded by the AVR ISP programmer).

Downloading Your Program

• Connect your AVR ISP to your circuit (as shown above). Make sure that you do not reverse the orientation of the connector

• Apply power to your circuit

• From your program directory, type: make program

• Once your the download is complete, your processor will be rebooted automatically.

Hints

• It is always a good idea to flash an LED in some unique way at the beginning of your program. This way, you can be sure that your processor is receiving power and that the power supply is stable.

• For delay_us() implementation, see: delay_us_test.c

fagg [[at]] cs.ou.edu

Last modified: Mon Apr 11 16:54:31 2005