4.5
APB energy meter registers
The IOFPGA contains the APB energy meter registers.
This section contains the following subsections:
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4.5.1 APB energy register summary
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4.5.1
APB energy register summary
The APB energy meter registers contain values that represent supply currents, supply voltages, and
power consumption in the Juno r2 SoC.
The IOFPGA provides energy registers that measure the instantaneous current consumption,
instantaneous voltage supplies, instantaneous power consumption, and cumulative energy consumption
of the Cortex-A72 cluster, the Cortex-A53 cluster, the Mali-T624 GPU cluster, and the fabric of the Juno
r2 SoC outside the clusters, that is, the parts of the chip that operate from the VSYS power supply.
Caution
You cannot use a core in one cluster to obtain a current or power consumption value of the same cluster.
Because the process of reading a current or power register alters the current and power consumption of
that cluster, such a measurement is not valid.
For this reason, you cannot use a Cortex-A72 core to obtain the instantaneous current or power
consumption of the Cortex-A72 cluster. You must use one of the Cortex-A53 cores to obtain these values
for the Cortex-A72 cluster.
Similarly, you cannot use a Cortex-A53 core to obtain the instantaneous current or power consumption of
the Cortex-A53 cluster. You must use one of the Cortex-A72 cores to obtain these values for the
Cortex-A53 cluster.
Note
Providing that the measurement process takes a short time relative to the application process, you can use
a core in one cluster to obtain the cumulative energy consumption of the same cluster. This is because the
cumulative energy value is a long-term measurement and the short time spent in reading the energy
register does not greatly affect the result.
Therefore you can use a Cortex-A72 core to measure the cumulative energy consumption of the
Cortex-A72 cluster and a Cortex-A53 core to read the cumulative energy consumption of the Cortex-A53
cluster.
4 Programmers Model
4.5 APB energy meter registers
ARM 100114_0200_03_en
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