We need a permanent storage for our Linux installation. The ML403 board contains a flash memory which is the perfect place to store our Linux OS to to be used during bootup of our system. To be able to read to and write from the flash memory we have to add an External Memory Controller (EMC). Let's do that.
The EMC supports up to four memory banks. We will use only one.
Generate addresses
The flash memory that comes with the ML403 board is 512 MB and with a 32 bit databus we will have a 128 MB address range.
Software platform settings
We have to tell the software where the flash is located. Open the Software->Software Platform Settings window and select OS and Libraries. Here we specify which memory bank we use (0) and the name of the external memory controller.
OPB External Memory Controller
The OPB EMC receives control signals from the OPB to read and write to external memory devices. The OPB EMC provides an interface between the OPB and one to four external banks of memory components. The EMC supports OPB data bus widths of 8,16 & 32 bits, and memory subsystem widths of 8,16 & 32 bits. The OPB EMC supports the OPB V2.0 byte enable architecture. Any access size up to the width of the OPB data bus is permitted. When the width of the memory is less than the width of the OPB, multiple memory cycles are performed to transfer the data width of the bus if data-width matching has been enabled for that memory bank. The OPB EMC provides basic read/write control signals and the ability to configure the access times for read, write, and recovery times when switching from read to write or write to read. When the OPB EMC is set for flash memory control it is organized like an SRAM interface. The OPB EMC assumes that the Flash programming circuitry is built into the Flash components and that the command interface to the Flash is handled in software.
