The Debug Access Port (DAP) in a CoreSight system allows access to legacy JTAG chains via a dedicated JTAG-AP access port. Initial support for JTAG-AP debug was available for ARM11 systems in RealView ICE (RVI 3.1). Support for both ARM9 and ARM11 based systems was added in RVI 3.2.

This FAQ provides configuration steps to allow RVI/RVD to debug ARM cores behind a CoreSight JTAG-AP. (The following screenshots are provided as an example configuration for an ARM1176JFZ-S based system. (Please note: the actual settings may differ from your hardware.)

1. Connect to your RVI.

2. Click Auto Configure Scan Chain.  An ARMCS-DP (DAP) template should appear in your scan chain.

3. Add the JTAG-AP template for your core to the scan chain by clicking Add Device….(for example: ARM1176JZF-JTAG-AP).

   Note: ROM table reads are not supported by JTAG-AP based systems.

   

4. Click on the JTAG-AP component in your scan chain and click Configuration.

5. Set the "CoreSight AP index" to match the index of the DAP JTAG-AP in your system.

6. Set the "JTAG-AP Port index for core", to match the index of the JTAG-AP Multiplexor port to which the ARM core is connected.

   

   Note1: If you have more than one device on the scan chain, please see the RVI 3.2 User guide documentation for details on how to set pre and post scan IR and DR bits appropriately.
                                                                               
7. Save and close the configuration. It should now be possible to connect to the core in RealView Debugger (RVD)