3.11.5. ETB RAM Write Pointer register

The RWP register characteristics are:

Purpose

The RAM Write Pointer register sets the write pointer to the required value. The Write Pointer writes entries from the CoreSight bus to the Trace RAM. During trace capture, the pointer increments when the formatter asserts the DataValid flag. When this register wraps around from its maximum value to 0, the Full flag is set. You can also write to this register through APB to set the pointer for write accesses.

You must not write to this register when trace capture is enabled, FFSR.FtStopped is 0, and CTL.TraceCaptEn is 1. When trace capture is enabled, it is not possible to update the register even if you do a write operation.

You can also read this register to determine which memory location is currently referenced. ARM recommends that addresses are 128-bit aligned when you use the formatter in normal or continuous modes.

Usage constraints

There are no usage constraints.

Configurations

This register is available in all configurations.

Attributes

See the register summary in Table 3.79.

Figure 3.77 shows the bit assignments.

Figure 3.77. RWP register bit assignments

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Table 3.84 shows the bit assignments.

Table 3.84. RWP register bit assignments

BitsNameFunction
[31:10]Reserved

-

[9:0]RAM_Write_Pointer

The RAM Write Pointer Register sets the write pointer to the required value. The write pointer writes entries from the CoreSight bus to the Trace RAM.


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