An external dataflash is provided with the AVR Butterfly. This is the 4-megabit serial DataFlash from Atmel, type AT45DB041B. More information about the DataFlash can be found in the datasheet available at the Atmel web site.

The DataFlash is connected to the SPI interface. This means that in addition to communicate with the ATmega169 on the AVR Butterfly, it can also be accessed externally through the ISP connector.

Note: If the DataFlash is to be accessed externally, the ATmega169 on the AVR Butterfly must be set to disable its own SPI interface to avoid contention on the interface
Figure 1. DataFlash

Figure 2. DataFlash Schematic