MegaCore | Arduino hardware package for ATmega64 ATmega128

This installation method requires Arduino IDE version 1.6.4 or greater. Click on the "Download ZIP" button in the upper right corner. Extract the ZIP file, and move the extracted folder to the location "~/Documents/Arduino/hardware". Create the "hardware" folder if it doesn't exist. Open Arduino IDE, and a new category in the boards menu called "MegaCore" will show up. PlatformIO is an open source ecosystem for IoT development and supports MegaCore.
Open the Arduino IDE.
Open the File > Preferences menu item.
Enter the following URL in Additional Boards Manager URLs: https://mcudude.github.io/MegaCore/package_MCUdude_MegaCore_index.json
Open the Tools > Board > Boards Manager... menu item.
Wait for the platform indexes to finish downloading.
Scroll down until you see the MegaCore entry and click on it.
Click Install.
After installation is complete close the Boards Manager window.
Ok, so you're downloaded and installed MegaCore, but how to get started? Here's a quick start guide:.
Hook up your microcontroller as shown in the pinout diagram. If you're not planning to use the bootloader (uploading code using a USB to serial adapter), the FTDI header and the 100 nF capacitor on the reset pin can be omitted.
Open the Tools > Board menu item, and select ATmega64, ATmega128, ATmega1281, ATmega2561, ATmega640, ATmega1280, ATmega2560, AT90CAN32, AT90CAN64 or AT90CAN128.
Select your preferred clock frequency. 16 MHz is standard on most Arduino boards.
Select what kind of programmer you're using under the Programmers menu.
Hit Burn Bootloader. If an LED is connected to pin PB5/PB7, it should flash twice every second.
Now that the correct fuse settings is sat and the bootloader burnt, you can upload your code in two ways: Disconnect your programmer tool, and connect a USB to serial adapter to the microcontroller, like shown in the pinout diagram. Then select the correct serial port under the Tools menu, and click the Upload button. If you're getting some kind of timeout error, it means your RX and TX pins are swapped, or your auto reset circuity isn't working properly (the 100 nF capacitor on the reset line). Keep your programmer connected, and hold down the shift button while clicking Upload. This will erase the bootloader and upload your code using the programmer tool.
Here's some simple schematics for the ATmega64/128/1281/2561/CAN32/CAN64/CAN128 and ATmega640/1280/2560 showing a minimal setup using an external crystal. Omit the crystal and the two 22pF capacitors if you're using the internal oscillator. Click to enlarge:.