3.11.3. ETB RAM Read Data register

The RRD register characteristics are:


When trace capture is disabled, the contents of the ETB Trace RAM at the location addressed by the RAM Read Pointer Register are placed in this register. Reading this register increments the RAM Read Pointer Register and triggers a RAM access cycle.

When trace capture is enabled, a read from this register outputs 0xFFFFFFFF when the following conditions are met:

  • FFSR.FtStopped is 0

  • CTL.TraceCaptEn is 1

  • ETB RAM attempts a read operation

In this situation the RAM Read Pointer Register does not auto-increment.

A constant output of 1s corresponds to a synchronization output in the formatter protocol that is not applicable to the ETB, and so can be used to indicate a read error when formatting is enabled.

Usage constraints

There are no usage constraints.


This register is available in all configurations.


See the register summary in Table 3.79.

Figure 3.75 shows the bit assignments.

Figure 3.75. RRD register bit assignments

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Table 3.82 shows the bit assignments.

Table 3.82. RRD register bit assignments


Data read from the ETB Trace RAM.

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