ARM Technical Support Knowledge Articles

Can I connect to an ARM core with a debugger if it is daisy-chained with non-ARM devices?

Applies to: DSTREAM, RealView ICE and Trace (RVI / RVT)


Both DSTREAM and RealView ICE (RVI) units can connect to an ARM core which is daisy-chained with other devices as long as all the devices in the scan-chain have standard TAP controllers. When you connect with your debugger to the ARM core in the scan-chain, the JTAG tool puts all the other devices in bypass mode.

ARM JTAG tools have information about a limited number of non-ARM devices, so auto-configuration may not work in all circumstances. However, you can define a custom scan chain by adding 'UNKNOWN' devices and configuring the IR (Instruction Register) Length for each device via the 'Debug Hardware Config' (formerly known as 'RVConfig') utility.

Note : Each individual device must be added to your target JTAG scan chain configuration via 'Debug Hardware Config' utility.

Details about how to do this are available in the DSTREAM / RVI user guides, see

Article last edited on: 2011-11-04 12:00:54

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