Connecting External Flash IC

Top  Previous  Next

The EM500W platform includes fd. object (with the exception of the fd.copyfirmware method). For this to work, an external flash IC must be connected to the EM500.

As shown on the schematic diagram below, this flash IC is ATMEL AT45DB041. Since the EM500 has a dedicated flash memory configuration, the flash IC will be used exclusively by the fd. object and provide 1MB of storage.

The 5.1K pull-up resistor is needed to "sharpen" SPI clock signal. EM500's bidirectional GPIOs allow interconnecting SI and SO lines (this saves one GPIO line!).




For the fd. object to work, it must be enabled first. Do this through Project Settings -> Customize dialog.



DO NOT enable fd. object unless you actually have the flash IC attached. When the fd. object is enabled, the EM500 will attempt to detect the flash IC presence. That is, the EM500 will try to access the flash through the SPI interface. This means that there will be signals on GPIO4 (CS), GPIO3 (CLK), and GPIO1 (DI/DO). Flash IC detection may interfere with the operation of your device (if you have something else connected to these GPIOs).