User manual
AVR Butterfly User Guide -25
4271C–AVR–04/05
Table 3-2. USI
3.9 External
DataFlash
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:
http://www.atmel.com/products/DataFlash/
The DataFlash is connected to the SPI interface. This means that in addition to commu-
nicate 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 But-
terfly must be set to disable its own SPI interface to avoid contention on the
interface.
Figure 3-19. DataFlash
Figure 3-20. DataFlash Schematic
AVR Butterfly USI
Pin 1 (USCK/SCL)
Pin 2 (DI/SDA)
Pin 3 (DO)
Pin 4 (GND)