4.2.5. CoreSight system configuration

CoreSight systems consist of a DAP that comprises the following components:

Debug components are attached to the buses, and are accessed through the APs on the DAP. CoreSight debug components are configured with the index of the AP to which they are attached, and the base address on the bus.

The DAP can also contain a JTAG-AP that enables the connection of JTAG devices on internal scan chains, for example ARM11 cores. JTAG devices must be configured with the AP index of the JTAG-AP, the JTAG port on the AP, and the pre-bits and post-bits for both IR and DR scans for the particular device. For more information see Configuring devices.

CoreSight components are associated with a DAP, so they are placed on the scan chain (or SWD connection) after the DAP with which they are associated. The DAP is represented on the scan chain by the ARMCS-DP device. CoreSight components use no space on the scan chain, so the order in which they are placed on the chain is not important, provided that they are placed between the DAP and the next real JTAG device.

CoreSight Association files

CoreSight systems can contain many trace sources and sinks. To enable RealView Debugger to capture trace correctly from a system, and to associate the trace information with the source that generated it, you must use a CoreSight Association file.

To use such Association files in RealView Debugger, you must use RVConfig to configure the device list for the RealView ICE connection. In RVConfig (see Figure 4.8) click the Trace Associations... button, and the Trace Association Editor dialog box displays. See Figure 4.17.

Figure 4.17. Trace Association Editor dialog box

Trace Association Editor dialog box

The devices shown in the Trace Association Editor dialog box reflect the order of those in the scan chain. To expand the details for a device, either double-click on its name, or click on the device’s + button. Figure 4.17 shows the expanded details for a device, with the cursor located on the bracketed text under the Association column. To assign the required association, double-click on the bracketed text.

In the Edit Association dialog box that displays, select the required options from each of the two available drop-down menus. See Figure 4.18.

Figure 4.18. Edit Association dialog box

Edit Association dialog box

When you have finished, click OK to return to the Trace Association Editor dialog box, where you can assign associations for other devices as required. To change any associations listed under the Association column, double-click on that association, then in the Edit Association dialog box either type your required text in the highlighted field, or select an option from the right-hand drop-down menu. Click OK to return to the Trace Association Editor dialog box.

To delete a single association, select it and click Delete. You are not asked for confirmation to delete.

To delete all the associations in the system, click the Delete All button. You are not asked for confirmation to clear.

To save your file if required, click the Save... button. When the Save RealView Associations File... dialog box displays, save your file in an appropriate directory.

To use a saved file, click the Load... button. When the Load RealView Associations File... dialog box displays, browse the list, locate and select the appropriate .txt file, then click Open.

To return to the RVConfig dialog box click OK, and in the scan chain an asterisk appears in a device box to denote that the device has an association assigned to it.

In clicking OK to confirm your changes, if the components are not in an order suitable for trace by RealView Debugger v3.1, you are asked to confirm whether you want to have the devices re-ordered automatically. See Figure 4.19.

Figure 4.19. Trace warning dialog box

Trace warning dialog box

Note

If you select No you are returned to the scan chain, where your associations have been completed as required. However, because no re-ordering has been made, your associations are not compatible with RealView Debugger.

For more information on CoreSight Association files, see Association Files.

Reading the CoreSight ROM table

If the target system contains a valid CoreSight ROM table, this can be used to configure the CoreSight devices. To do this, right-click on the ARMCS-DP and select the Read CoreSight ROM Table option. Alternatively, select the Read CoreSight ROM Tables checkbox located in the Auto Configure panel.

CoreSight autodetection

Autodetecting a CoreSight system results in the ARMCS-DP device being found. This device represents the DAP in a CoreSight system. The debuggable devices connected to the DAP is not found. If the device contains a valid CoreSight ROM table, you can determine what CoreSight devices are available by right-clicking on the ARMCS-DP device and selecting Read CoreSight ROM Table. Alternatively, select the Read CoreSight ROM Tables checkbox located in the Auto Configure panel. See CoreSight system configuration.

Autodetecting Serial Wire Debug

SWD does not support a scan chain in the same way that JTAG does. Autoconfiguring in SWD mode results in one ARMCS-DP device being found. The Read CoreSight ROM Table option can be used as described in CoreSight autodetection.

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