ATMEL HOWTO

Common Problems

• text region full: Make sure the "optimization" flag is set (see above). You will probably also need to re-add "F_CPU"
• Oulib error: F_CPU not defined. Re-add "F_CPU" as above. After this, perform a "build clean" and a "rebuild all"
• Many things undefined, such as DDRB and PORTB. Re-set your device to "atmega2560"

Step 2 (non-AVR Studio): Creating and compiling your program

• Create your C program (you can start with this sample program: led_flash.c). You will need a text editor of some form (e.g., xemacs)

• Create a makefile (start with this sample makefile)

• For class, the following files can be found in your svn tree. If you are not using this tree, then grab a current version of OUlib: libou_atmega2560.a and oulib.h and place it in your project directory (or place a shortcut to these files in your project directory). Also download oulib_serial_buffered.h and buffer.h.

• 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:
  • Use your shell
  • 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.lss: 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

• From your program directory, type: make program
  • If you run into device permission problems, you can do this as root as a temporary measure (to configure for standard user use, you must configure udev properly). To fix this permanently, see the installation page.

• Setting the programmer frequency: (if you run into trouble)
  • Enter interactive mode:
    avrdude -c avrispmkII -P usb -p m8 -F -u -t

  • parms will give you the current clock period

  • sck [period] will set the clock period
    Use 1 for high speed programming (not possible unless you are using the external 16 MHz crystal)
    Use 10 for low speed programming (compatible with the internal clock)
  • quit

• Configuring for use with the external crystal: (again, use if you run into trouble)
  • Set programmer frequency for low speed programming (above)

  • Use make setfuse (make sure you have the latest copy of the makefile)

  • Set programmer frequency back to high speed programming

Step 3: A Basic Circuit

You may use the original mega2560/first_circuit.sch file if you wish (this is an Eaglecad file).

Notes:

• L1 and L2: LEDs used in the sample program. Note that the polarity of the LEDs is critical.
• You need a resistor in series with each of the LEDs (1K ohms will do).

Hints

• It is always a good idea to flash a 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

• You can find other mega 2560 examples in the examples_2560 directory

• You can find other examples in the examples directory (note that some of these are specific to the atmega8 processor, though they will often be compatible with the 2560)

• You can also download the oulib source and examples: oulib_2012_02_14.tar.

• AVR Freaks has a tutorial on bit manipulation in C

• Suha has a tutorial on manipulating ports on the Atmel (note that this is a slightly different processor than the mega8, but the principles are the same).

Atmel Mega2560 Details

• Full Atmel Mega2560 Manual

• Arduino Schematic: Nice version and Complete version

• OUlib Module Documentation. We will make heavy use of this document in the class.

• AVR ISP Userguide

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

• AVRDude Userguide

andrewhfagg [[at]] gmail.com

Last modified: Thu Jan 22 11:37:33 2015