ARM DS-5 Using the Debug Hardware Configuration Utilities

Creating debug hardware target configurations5.5 About configuring a device listYou can configure a device list using the following methods:• autoconfiguration• manual configuration.5.5.1 AutoconfigurationWhen autoconfiguring a device list, debug hardware interrogates the scan chain andautomatically selects the correct templates for supported ARM target devices, then adds themto the scan chain in the correct order. This takes place at the current clock speed:• If you are using a fixed clock speed, but debug hardware detects one or more devices thatrequire adaptive clocking, it automatically selects adaptive clocking.• If you are using adaptive clocking, but debug hardware does not detect any devices thatsupport adaptive clocking, an error message is generated. Select a fixed clock speed.• If the clock speed is too high, some devices on the scan chain might not be detected. Ifyou suspect that this is happening, decrease the clock speed.WarningAutoconfiguring can be intrusive and stop your development platform from operating normally.If you want to connect to a target on your development platform without performing a reset andstop, you must manually add the devices to the scan chain.NoteAutoconfiguration is disabled in Debug Hardware Config if the current debug hardwareconfiguration has a platform assigned to it.For Serial Wire Debug (SWD), autoconfiguring a system identifies the target devices on yourdevelopment platform by reading appropriate SWD registers. The value of this register isusually set by the engineers that integrate the devices into a design. It is not set within the ARMdevices themselves. For more information, see the ARM datasheet or technical referencemanual for the processor that you are integrating.NoteBefore you autoconfigure a target that supports both JTAG and SWD, you must first enable UseSWJ Switching in the Advanced configuration settings.5.5.2 Manual configurationYou can add devices manually to a scan chain. You must do this if your development platformincludes:• Unsupported devices. That is, devices for which no templates are provided by the debughardware unit.• Supported devices that are not detectable by the debug hardware unit.ARM DUI 0498F Copyright © 2010-2012 ARM. All rights reserved. 5-9ID021112Non-Confidential