No longer support for Megaload


MegaLoad is a Windows based boot loader for all Atmel ATMega microcontrollers that support the Bootloader function.  MegaLoad is a solution for everybody who wants fast loading (~8k in 3 seconds) and easy software upgrade via MCU RS232 port.

MegaLoad is written in Visual C# and the source code is available for 100$usd that can be pay via paypal at


  • support device larger than 128k flash
  • Small Bootloader code. Only 256 words if only flash program is need (512 word if flash & EEPROM)
  • Only embedded requirement is RS232 connector like a MAX232.
  • Communicates at 9600,19200,38400,57600,115200bps on Com1 to 20
  • Simple Monitor window is available to help you to debug your code
  • Checksum everywhere to secure data
  • Automatic page retry, if error in flash programming
  • Automatic byte retry, if error in EEPROM programming
  • Manual set & clear DTR,RTS if need.
  • Reset button


System Requirements

  •  Windows, .NET framework 2.0 runtime
  • RS232
  • ATMega



Megaload Tutorial

Megaload Software

Megaload Bootloader Code for ICCAVR

Megaload Bootloader for CodeVision

128 Comments to “MegaLoad”

  • Alex September 5, 2012 at 6:49 am

    Megaload closes when you try to program the file intel-extended.
    How programm file size of more >64kb (ex. mega128)?

  • Sylvain September 5, 2012 at 12:40 pm

    Hmmm I never hear about that,  I have no idee, are you shure that your file is valid?

  • Alex September 6, 2012 at 6:39 am

    Yes. If set Intel-stanard, IAR write error "Error[e122]: The address 0×10010 is too large to be represented in the output format 'intel-standard'". I changes linker output format to intel-extended and compiling without errors. In my opinion, MegaLoad not supported this format.

  • Alex September 6, 2012 at 9:06 am

    O, yeah! Working is good if delete line in hex-file
    >>> :0400000300000000F9


  • Sylvain September 6, 2012 at 11:43 am

    I have no clue,  megaload is supposed to support all hex format, maybe there is something strange in the composition of IAR,  
    What is the purpose of the line you had delete? It's look like a jump to the start of your code ???

  • Alex September 6, 2012 at 11:55 am

    This line present in intel-extended format. In intel-standard this line is absent.

  • Sylvain September 6, 2012 at 11:57 am

    Ok but did you know what is the meening of this line? and what the byte are for

  • Alex September 6, 2012 at 12:07 pm

    No, I do not know. Found experimentally that the cause of it.

  • Rui Henriques November 22, 2012 at 11:24 pm

    [...] importante perceber como vamos descarregar o nosso programa para lá. Para isso uso o um programa MegaLoad (aconselho que dêem uma vista de olhos no site MicroSyl, possui informações importantes). Se [...]

  • lukas December 27, 2012 at 11:22 am

    megaload writes me:"Programming flash…. please wait." What I do make?

  • admin December 27, 2012 at 1:31 pm

    Did you place the bootloader in the mcu first? with the good settings?

  • Alireza January 13, 2013 at 6:54 am

    How can I change these files for Codevision,Atmega16A,with 11.0592 external crystal.
    As I saw in main.c file, you use " #include "iom16v.h" " for atmega16, but Codevision doesn't have this hex file.
    Sorry if my question is too basic, I'm beginner in using of bootloader.

  • admin January 13, 2013 at 4:18 pm

    It’s not a beginner question, There is a lot of work to do, but I don’t know anything of codevision


  • Pranjal January 15, 2013 at 8:16 am

    The code files you have given for CodeVision just doesn't work!!!! 
    I changed the #include "iom16v.h" to the file the CodeVision uses, but then I got more errors. It just doesn't work. 

  • admin January 15, 2013 at 3:33 pm

    That’s a user how wrote this code it’s not me,

  • xiaofeng January 20, 2013 at 2:38 pm

    Do you know “BootLoader 4.3 for MegaLoad 4.0”?
    //* Version 4.0 June 2005
    //* 1.0 : First Release
    //* 1.1 : Add auto baud rate, code smaller
    //* 1.2 : Correct a bug with file larger than 65280 bytes.
    //* 2.0 : All in one source file that fit in 512 Words
    //* 3.0 : Add EEprom programming
    //*       Add RS485 half duplex support
    //*       Add LockBit programming
    //* 3.1 : Correct a problem with interupt vector for M8/16/32/162/8515/8535
    //*       Change some #define to be more clear
    //* 3.2 : Add support for M48/M88/M168
    //* 4.0 : Change code to work with MegaLoad .NET 4.0 
    //*       Add M165/325x/645x/168/329x/649x/406/640/128x/256x
    //* 4.1 : Add ATMegaCAN128
    //* 4.2 : Some change for M88 tested by duane
    //* 4.3 : Problem with UART2,3,4 found my Matthew, Problem with ICC new version corrected
    can you help me?

  • USB bootloaders for AVR microcontrollers - Do It Easy With ScienceProg February 5, 2013 at 1:08 pm

    [...] Sylvain Bissonnette,, COM, 11500bps, ICCAVR(C); Megaload.NET; Various [...]

  • arash April 24, 2013 at 11:21 am

    i need bootloader for mega1284!!! 

  • LEE June 12, 2013 at 8:27 am

    i have a question.
    "Megaload" in 'send reset' button to what function?

  • admin June 13, 2013 at 3:28 am

    It’s only send “RESET” string via the serial port and YOUR aplication should handle this string

  • Bob October 4, 2013 at 11:22 am

    Hi Sylvester
    I've used V6.3 on Win XP using a usb virtual comm port. Everything works well.
    I've now installed the V6.3 on a Win7 64 bit machine.
    It does download, but the COM port number is off by 1. 
    The OS and other terminal programs list the USB i/o at COM15 but the MegaLoader needs COM16 in the drop down box.
    Anything I can try?

  • admin October 4, 2013 at 7:12 pm

    Could you map your comport to another com numer dans see what is the result???

  • Bob October 11, 2013 at 10:47 am

    Hi Sylvester
    I've tried mapping to a different COM number – same result,  OS and other terminal programs see port at COM(n) but MegaLoad at COM(n+1).  
    Serial device is the ATEN USB to serial bridge, driver version V3.3.7.131 Date: 15 Oct 2009
    I'll check for a newer driver, and let you know … Windows says driver is up to date.
    It's a very useful program.

  • Bob October 18, 2013 at 3:10 pm

    Hi Sylvester
    The com port issue I experienced has been solved by clearing in the registry the list of com port allocations from other usb devices. Possibly the OS had an issue with its numbering.
    Thanks again.

  • Orchidice December 14, 2013 at 8:32 am

    Hello admin,
    I'm using Mega32L with 1K bootload 9600bps setting. When I downloaded bootload.hex itself to the flash using megaload, it ran #241 pages, then it was pending all the time. There was message "Programming flash…. please wait" in status box. 
    I want to know how can I fix this issue, thanks!

  • admin December 14, 2013 at 2:12 pm

    You CAN’T programe the mcu with the bootloader.exe with megaload use av studio or orthers

  • Orchidice December 16, 2013 at 1:36 am

    I had already programed the bootloader.hex to the MCU use AV STUDIO. 
    I wanted to test if the bootloader can upgrade itself.
    So I used megaload to download the new bootloader.hex to the flash. It upgraded #241 pages, then stopped. 
    This is the problem, thank you for your help.

  • Orchidice December 16, 2013 at 7:54 am

    I solved the problem, when I programed BLB1 lock bit to 0. Thank you!

Post comment

Please note

All my source codes were taken from my personal projects.

Everything is for your information only. The C/C++ codes have been written
with ICCAVR. You can find the header and source CRT files by downloading their compiler.

All is for your information and everything is AS IS without any warranty of any kind. No other files are available and I don't make any modification for any body.



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