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Armega128 bootloader using windows hyper terminal

2017-12-22 07:08  
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If you are windows user, there is an easiest solution to program Atmega128 microcontrollers. In http://piconomic.co.za there is nice bootloader binary you can download and use for personal purposes.

First of all you will need to upload bootloader hex file (which is packed in) to Atmega128 and properly program fuses. For my Piconomic board I set fuses like this:

Atmega128 boot fuses

Then plug RS232 cable to computer COM2 (or COM1) port and then from windows select Start->All Programs->Accessories->Communication->HyperTerminal. HyperTerminal is program used for multiple communication purposes like connecting to other computer, telnet, modems and null modems.

Firs of all select connection type a€“ COM2:


After pressing OK you will be taken to COM2 connection properties:


After connection settings are done it is time to start bootloading. I have never thought it can be so easy. Just select Transfer->Send file in HyperTerminal program:


In the opening window select file you want to download. Just remember that binary has to be compiled asBINnotHEX. Second option is to select protocol a€“ how data will be sent to booloader. Bootloader is programmed to support Xmodem protocol:


Press Send button then Hyperterminal starts waiting for bootloader to respond:


Just press a€?Reseta€? button on your target board and sending will begin automatically. After sending of bin is finished program starts to execute uploaded program.

The AVR fuse bits have been set so that execution starts from the boot vector address. This means that the bootloader will always be executed first. The bootloader sends a ‘C’ character to start a transfer and waits for 1 second for a valid XMODEM-CRC data packet. If the transfer is not successful, it will jump to address 0×0000 and execute the application. This is why we start sending from Hyperterminal first and then press Reset button.

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