You can use the ETM7 in the ARM7TDMI and ARM720T (Rev3) system using a single bidirectional data bus. The D[31:0] bus must be connected to both the ETM7 RDATA[31:0] and WDATA[31:0] buses. In this case the ETM7 samples the data bus correctly for both read and write accesses. See Figure 3.1 for details of an example system using bidirectional buses.