PCB connections

It is recommended that you place the 20-way JTAG header as closely as possible to the target device, because this minimizes any possible signal degradation caused by long PCB tracks. The header must be a 0.1 inch pitch standard box header.

The following figure shows the layout of possible PCB connections:

Figure 8. Typical PCB connections

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  • The signals TMS and TDI must be pulled up on the PCB, as shown.

  • TCK must be pulled down on the PCB, as shown.

  • DBGRQ and DBGACK are not used by the ARM® tools, but are used by some third party tools. If your tools do not use DBGRQ and DBGACK, and your device has a DBGRQ input, this must be pulled down on the PCB.

  • RTCK is used by -S processor variants, such as the ARM966E-S processor. If your device does not use RTCK, then RTCK must be pulled down on the PCB.

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