Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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15.5.4.1. Timestamp Interpolater

The DSU implements the timestamp interpolator, there are two requirements which must be met to allow correlation between interpolated and non-interpolated timestamps.

First, in order to allow the timestamp interpolator to count the least significant 8 bits at a higher frequency without saturating the count value too early, the tsintp timestamp count input must be slowed to a count frequency between 1 Mhz and 50 Mhz. Since the timestamp generator is running 400 Mhz, this means we need to shift the timestamp value right by 5 bits and pad the upper bits (TSVALUEB[63:0] = 5’b00000, trace_timestamp[63:5]}) for a count frequency of 12.5 Mhz. Of course, this same right shift should be applied to every tsdec output (STM, PSS NOC Trace Observer, MPFE NOC Trace Observer).

Second, in a system where some subsystems use a timestamp interpolator and some do not, the subsystems without the timestamp interpolator must add the same number of extra zeroes (8-bits) to the LSB of the timestamp, to ensure that the timestamps are aligned between the subsystems. This applies to the STM, PSS NOC Trace Observer, and MPFE NOC Trace Observer.

This means that the following timestamp connections are used to make correlation between ETMs and the other trace macros (STM, NOC trace observers) easier.

Table 419.  Timestamp Connections
Module Direction Width
TSGEN Output 64-bit
DSU Input 64-bit
ETMs Input 64-bit
STM Input 64-bit
NOCs Input 48-bit