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

Behavioral Models5.4 TubeThe system messaging tube, Tube, is a simple method of passing system messages froma test program to the display, and enables a test program to stop the simulation.Figure 5-4 shows the tube module interface.XDXCSNXWENTubeSimulator displayand text fileFigure 5-4 Tube module interface diagramThe main sections of this module are:• message output to simulator• message output to file• simulation termination control.5.4.1 Signal descriptionsTable 5-6 lists the non-AMBA signals used by the tube module.Signal Type Direction DescriptionXCSN[3:0] External chip select Input These signals are active LOW chip enables.Table 5-6 Tube module signalsXD[31:0] External data Input This is the external data bus, that is sampled by this moduleduring write transfers.XWEN[3:0] External write enable Input This is the active LOW memory write enable. For little-endiansystems, XWEN[0] controls writes to the least significant byteand XWEN[3], the most significant. The example system isconfigured to be little-endian.ARM DDI 0243C Copyright © 2003, 2007 ARM Limited. All rights reserved. 5-7