AMBA Design Kit Technical Reference Manual - ARM Information ...

Behavioral Models5.1 External RAM,The external RAM module, ExtRAM, is a simple model of a 32K x 8 off-chip SRAM, thatcan be initialized with data from a local file. Figure 5-1 shows the external RAMmodule.A[14:0]CSnWEnOEnExtRAMDQ[7:0]Figure 5-1 AHB external RAM module interface diagram5.1.1 Programmer’s modelTable 5-1 lists the user-defined settings for the external RAM module.Table 5-1 User-defined settings for the external RAM moduleSignalTypeDefaultsettingDescriptionFILENAME Input filename - This points to the local input data file that is read in after reset.RAMDEPTH Memory depth 32 This sets the memory depth in KB. If the value is increased from thedefault setting, then the address input bus A must also be increased toenable all memory to be addressed.5.1.2 Signal descriptionsTable 5-2 lists the non-AMBA signals used by the external RAM module.Signal Type Direction DescriptionA[14:0] External address Input The external address inputTable 5-2 External RAM module signalsCSN Chip enable Input When LOW, this signal indicates that the chip has been selected andmust respond to the current transfer5-2 Copyright © 2003, 2007 ARM Limited. All rights reserved. ARM DDI 0243C