AM437x Power Estimation Tool

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AM43xx Power Estimation Tool


Introduction

The Power Estimation Tool (PET) allows users to gain insight into the power consumption of select Sitara processors. The tool includes the ability for the user to choose multiple application scenarios and understand the power consumption as well as how advanced power saving techniques can be applied to further reduce overall power consumption.

PET spreadsheet is comprised of two parts:

  1. Input – The input part of the spreadsheet is the mechanism in which users input device parameters needed for their application. Parameters include IP activities/loadings, desired power states, and power management usages.
  2. Output – The output part of the spreadsheet contains the information on SoC power consumption based on power calculations in the spreadsheet. The output report which includes leakage, active and total average power, as well as power management voltages, will be shown in this area.

The data presented in the PET spreadsheet are based on measurements performed on AM43xx revision 1.1 silicon, as well as estimates.


Note: The AM43xx PET applies to AM437x family devices (AM4376, AM4377, AM4378 and AM4379) and AM438x family devices (AM4382, AM4384 and AM4388).


INPUT

Download AM43xx Power Estimation Tool (PET) Spreadsheet here.

The Input part of the spreadsheet consists of 4 sections: General, Operating Performance Point(OPP), Processor Core Utilization, and Peripheral Module Utilization. To use the input part of the spreadsheet, users need to modify the input fields with their appropriate usage parameters. Cells that are designed for user input are light blue in color. Simply configure the light blue cells to a value most closely aligned with your intended scenario.

Briefly, the purpose of each of the 4 sections is:

  • General: configure the high-level system configuration such as junction temperature and power estimation mode.
  • Operating Performance Point(OPP): configure MPU OPP, MPU frequency and CORE OPP.
  • Processor Core Utilization: configure processor subsystem components.
  • Peripheral Module Utilization: configure peripherals.


Macro Buttons

The spreadsheet includes macros. If you can't run macros, please review your excel security settings described in below articles.
Change macro security settings in Excel (Office 2010)
Change macro security settings in Excel (Office 2007)


The input part of the spreadsheet has command buttons to run macros.

  1. "Wiki Article" - Navigate to this wiki article.
  2. "Default Settings" - Clear all settings and configure them to the default values.
  3. "Dhrystone" - Configure settings to the Dhrystone benchmark example application scenario. [MPU intensive, high power use case]
  4. "OS Idle" - Configure settings to Linux OS Idle example application scenario. [MPU idle, medium power use case]


General

This section allows users to choose DDR type, set a junction temperature (not ambient temperature) between 0C and 105C and power estimation mode.

  • Device Revision: PG1.1
  • DDR Type: LPDDR2, DDR3+VTT, DDR3L, None
  • Junction Temperature (°C) : 0 ~ 105 (negative values are not supported in the tool)
  • Power Estimation Mode : Max, Typ ('Max' accounts for the worst-case silicon process variation)


The spreadsheet presents information only for the full-featured device in the AM43xx family. However, since the spreadsheet breaks out the power consumption due to each module in the full-featured device, estimates for the other devices in the AM43xx family can be obtained by setting zero for the modules not present in the device under consideration. This will ensure that active power from the non-applicable modules are not included in the power tally. The device differences are summarized at the overview section in AM437x Product Page and AM438x Product Page.


Operating Performance Point(OPP)

This section allows the user to set an operating performance point (OPP) for MPU domain and CORE domain and MPU frequency.


Processor Core Utilization

Module utilization is the percentage of the available MHz at the selected OPP needed to meet the scenario processing requirement.

A separate utilization entry is provided for the Cortex-A9 ARM processor subsystem.

  1. MPU (Cortex-A9): 0 - 100 %

For the graphics accelerator subsystem, a separate utilization entry is provided:

  1. Graphics Accelerator: 0 - 100 %

For PRU-ICSS subsystem, a separate utilization entry is provided:

  1. PRU-ICSS (Programmable Real-Time Unit Subsystem)


Peripheral Module Utilization

This section is used to configure the activity on peripheral modules.

For each modules, a user can enter module utilization as a percentage (0-100). A separate utilization entry is provided for the following modules:

  • DDR EMIF (External Memory InterFace controller)
  • Display DSS (Dispaly SubSystem)
  • Camera (VPFE0/1)
  • USB(Universal Serial Bus) Port 0 or 1
  • Ethernet MAC
  • GPMC (General Purpose Memory Controller)
  • MMC (MultiMedia Card host controller)
  • McASP (MultiChannel Audio Serial Port)



OUTPUT

AM43xx Power Consumption

The power estimation tool generates a power analysis report in this section. The report lists power consumption in mW per power rail groups.

The AM43xx Power Estimation Tool models temperature and device process effects on device power consumption. Active power consumption is the power that is consumed by portions of the AM43xx that are performing some processing. Active power is independent of temperature, but dependent on voltage and module activity levels.

Important Notes and Limitations

The following notes and limitations apply to the AM43xx Power Estimation Tool:

  • It is up to the user to input reasonable utilization numbers for the MPU subsystem for the purposes of maximum power analysis. 90-100% loading on the subsystem is not realistic for most application scenarios.