9.1. About the ETB for CoreSight

The ETB provides on-chip storage of trace data using 32-bit RAM. Figure 9.1 shows the main ETB blocks.

Figure 9.1. ETB block diagram


The ETB accepts trace data from CoreSight trace source components through an AMBA Trace Bus (ATB). See the CoreSight Architecture Specification for a detailed description.

The ETB contains the following blocks:

Formatter

Inserts source ID signals into the data packet stream so that trace data can be re-associated with its trace source after the data is read back out of the ETB.

Control

Control registers for trace capture and flushing.

APB interface

Read, write, and data pointers provide access to ETB registers. In addition, the APB interface supports wait states through the use of a PREADYDBG signal output by the ETB.

The APB interface is synchronous to the ATB domain.

Register bank

Contains the management, control, and status registers for triggers, flushing behavior, and external control.

Trace RAM interface

Controls reads and writes to the Trace RAM.

Memory BIST interface

Provides test access to the Trace RAM.

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