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i.MXRT1021 ETM trace port size?

Question asked by Chris Eyre on Jul 18, 2019
Latest reply on Jul 18, 2019 by jeremyzhou

What is the supported ETM trace port size on the RT1021? The 1020 reference manual suggests that TRACEDATA can be 1, 2, or 4 bits and 4-bit mode is recommended (see 7.2.2.2 CoreSight trace port interface). However, this seems to conflict with the actual behavior of the device. With a debug connection to the 1021 evaluation kit. I observed that the ARM TPIU Supported Port Size register is fixed to 1 (0xE0040000=0x00000001). If my understanding is correct, this register indicates that only PORT_SIZE=1 is supported by the device and this cannot be changed. My evaluation kit has been modified to support ETM trace and I was able to verify that 1-bit ETM trace is working, but not 2-bit or 4-bit mode.

 

We are evaluating the 1021 as a possible migration from the K24. With the k24 we are using 4-bit TRACEDATA  mode and this seems to meet our needs. On the k24 I confirmed that the Supported Port size register indicates 4-bit mode is supported. ETM trace is important for our applications so I am concerned with the apparent limit of 1-bit ETM Trace and at this point it is unclear whether this will cause some kind of trace data bottleneck. 

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