3.2.5. Coprocessor control connections

To provide compatibility with both ARM7TDMI and ARM7TDMI-S, you must retime the CPA and CPB ARM inputs externally to the ETM7.

Note

If there are no coprocessors in your system, and you have tied CPA and CPB to the ARM processor HIGH, then the logic described below is not required, and you must also tie the CPA and CPB inputs to the ETM HIGH.

ARM7TDMI

The ARM7TDMI samples CPA and CPB on the rising edge of MCLK, when nWAIT is HIGH. Figure 3.3 shows the logic required to retime the CPA and CPB inputs to the ETM7.

Figure 3.3. Retiming CPA and CPB in ARM7TDMI

ARM7TDMI-S

The ARM7TDMI-S samples CPA and CPB on the rising edge of CLK, when CLKEN is HIGH. Figure 3.4 shows the logic required to retime the CPA and CPB inputs to the ETM7.

Figure 3.4. ARM7TDMI-S CPA and CPB connections

ARM720T

No retiming is necessary. The ETMCPA and ETMCPB outputs from the ARM720T must be connected directly to the CPA and CPB inputs of the ETM7.

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