9.4.1. 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.

Figure 9.8 shows the layout of possible PCB connections.

Figure 9.8. Typical PCB connections


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

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