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| Home > Configuring the ETM > Configuring the ETM parameters > Trace data width |
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This control enables you to set the width of the ETM trace data port, which determines the number of trace port pins that are used to broadcast trace information. This can be useful, for example, when trace port pins are multiplexed onto General Purpose Input/Output (GPIO) pins, and the hardware is configured to use these pins in their GPIO role. Only those widths supported by your TPA and target are enabled for selection.
The width of the ETM data port is configured by the processor manufacturer to one of the following sizes:
A 4-bit ETM data port using 9 output signals on the target being traced.
An 8-bit ETM data port using 13 output signals on the target being traced.
A 16-bit ETM data port using 21 output signals on the target being traced.
A 24-bit ETMv3 data port.
This size is not currently available for any trace hardware.
A 32-bit ETMv3 data port. This size is currently available only for ETB11™ trace hardware, when using on-chip tracing with RealView ICE. Also, if you are using ETB11 trace hardware, then this is the only size available.
A narrow port width reduces the bandwidth available to the target for sending trace data off-chip. This usually produces more FIFO overflows, which results in less data being generated. Therefore, the profiling quality is reduced.
| Copyright © 2006-2009 ARM Limited. All rights reserved. | ARM DUI 0322D |
| Non-Confidential | |
| PDF version | |
| Home > Configuring the ETM > Configuring the ETM parameters > Trace data width |