3.5.45. Timestamp Event Register, ETMTSEVR, ETMv3.5

The ETMTSEVR characteristics are:

Purpose

Defines an event that requests the insertion of a timestamp into the trace stream.

Usage constraints

There are no usage constraints.

Configurations

This register is only available in ETMv3.5 or later. This register is implemented only when bit [22] of the ETMCCER is set to 1. See Configuration Code Extension Register, ETMCCER, ETMv3.1 and later. If this register is not implemented, this register is RAZ/WI.

Attributes

See the register summary in Table 3.3 and Reset behavior.

Figure 3.42 shows the ETMTSEVR bit assignments.

Figure 3.42. ETMTSEVR bit assignments

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Table 3.56 shows the ETMTSEVR bit assignments.

Table 3.56. ETMTSEVR bit assignments

Bits

Version [a]

Description

[31:17]-Reserved.

[16:0]

v3.5

Timestamp event. Subdivided as:

Function, bits [16:14]

Specifies the function that combines the two resources that define the event.

Resource B, bits [13:7] and Resource A, bits [6:0]

Specify the two resources that are combined by the logical operation indicated by the Function field.

For more information see ETM event resources.

[a] The first ETM architecture version that defines the field.


You can program this register so that an external device or a programmable event causes the ETM to insert a timestamp in the trace stream. For example, you might program it so that the execution of a DMB instruction on another processor causes the insertion of a timestamp.

Resource identification and event encoding describes how you define a timestamp event.

ARM strongly recommends that you do not program this register with the Always true event, event 0x6F. If you program the Timestamp event to be always true the ETM inserts many timestamps into the trace stream, and the trace FIFO is likely to overflow.

Typically, you program the Timestamp Event Register to cause the ETM to insert a timestamp in the trace stream periodically. You can do this by programming one of the ETM counters to decrement every cycle, and programming the Timestamp Event Register so that the timestamp event occurs each time the counter reaches zero.

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