AM35x Power Estimation Tool

Content is no longer maintained and is being kept for reference only!

Introduction

The Power Estimation Tool (PET) provides users the ability to gain insight in to 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 is comprised of three modules:

1. Input Spreadsheet – this downloadable 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. Multiple operating conditions can be applied along with time slots for each state.
2. Spreadsheet Upload- upon completion of the input spreadsheet, users can then upload the spreadsheet to TI for the power consumption analysis. Registration and legal agreement acceptance is required for the upload.
3. Power Analysis Report-contains the information on power consumption based on the spreadsheet upload. The report includes leakage, active and total average power, as well as power management voltages will be sent to the user via email.

Input Spreadsheet

There are two types of input spreadsheet. Standard input spreadsheet is designed for estimating the power for single application scenario. Advanced input spreadsheet has additional columns for multiple application scenarios. The power estimates from advanced input spreadsheet will be an average power of multiple application scenarios that configured in the input spreadsheet.

The input spreadsheet consists of 4 sections: tables A, B, C and D. Using the input spreadsheet involves simply entering appropriate usage parameters. Cells that are designed for user input are light green in color. To use the spreadsheet, simply configure the light green cells to a value most closely aligned with your intended scenario.

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

• Section A: configure the high-level system configuration such as junction temperature, power estimation mode, IO voltage setting and ARM clock frequency.
• Section B: configure ARM and graphics accelerator (SGX) subsystem components.
• Section C: configure peripherals.
• Section D: configure analog macros.

The spreadsheet applies to AM3517 and AM3505 devices.

Download AM35x PET Input Spreadsheet here.

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 2007)
Enable macros to run (Office 2003)

Macro Buttons

The input spreadsheet has command buttons to run macros as shown in Figure 1.

Figure 1. Macro Buttons

1. "Click to Submit" - Navigate to upload page.
2. "Default Settings" - Clear all settings and make them to default values.
3. "Music Playback Example" - Configure settings to music playback example application scenario.
4. "Video Capture Example" - Configure settings to video capture example application scenario.
5. "Standy Example" - Configure settings to Standby example application scenario.

Section A: High-Level System Configuration

This section allows the user to set a junction temperature (not ambient temperature) between 0C and 105C, power estimation mode VDDSHV IO voltage (1.8 V or 3.3 V) and ARM clock frequency as shown in Figure 2.

Figure 2. Section A of AM35x PET input spreadsheet allows configuration of junction temperature, power estimation mode, IO voltage setting and ARM clock frequency.

For modules powered by the VDD_CORE rail is assumed with the configuration for voltage and interconnect clocks shown in Table 1 below.
Table 1. Voltage and Clock configurations.

Parameter	Value
VDD_CORE voltage	1.2V
ARM clock frequency	500/600MHz
CORE_CLK frequency	332MHz
L3_ICLK frequency	166MHz
L4_ICLK frequency	83MHz
SGX_ICLK frequency	110MHz
SDRC_CLK frequency	166MHz
GPMC_CLK frequency	83MHz
SYS_CLK frequency	26Mhz

• Junction Temperature (°C) : 0 ~ 105 (Negative value is not supported in the tool)
• Power Estimation Mode : Max, Typ
• Mode : Active and Standby

The spreadsheet presents information for only the full-featured AM3517 device in AM35x family. However, since the spreadsheet breaks out the power consumption due to each module in the AM35x, estimates for the AM3503 can be obtained by setting zero for the module not present in the device under consideration. This will ensure active power from the non-applicable module is not included in the power tally. The device differences are summarized as follows:

• AM3517 (device with ARM and SGX)
• AM3505 (ARM only device)

Section B: Processors

This section allows the user to set an utilization for the ARM and SGX subsystems, as shown in Figure 3.

Figure 3. Section B of the AM35x input spreadsheet allows configuration of processors' OPP and utilizations).

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-A8 ARM processor and the NEON SIMD engine.

1. Cortex-A8 (ARM Cortex-A8 processor core)
2. Cortex-A8 NEON (General purpose SIMD engine)

Section C: Peripherals

This section is used to configure the activity on peripheral modules as shown in Figure 4.

Figure 4. Section C of the AM35x PET Input Spreadsheet allows configuration of peripherals.

The utilization of video/imaging interface modules such as DSS (Display Sub-System) and VPFE (Video Processing Front End sub-system) are configured by the following parameters.

• Horizontal Pixels : 0 ~ 1368
• Vertical Pixels : 0 ~ 768
• Frame per Second : 0 ~ 60
• Bit per Pixel : 0 ~ 32
• Blanking Period [%] : 0 ~ 10

For each modules, a user can enter module utilization as a percentage. A separate utilization entry is provided for the following modules.

• SDMA (system direct memory access controller)
• SDRC (SDRAM controller)
• GPMC (general purpose memory controller)
• USB (universal serial bus)
• EMAC (Ethernet MAC)
• HECC (High-End CAN Controller)
• MMC (multimedia card host controller)
• McBSP (multi-channel buffered serial port)
• UART (universal asynchronous receiver/transmitter)
• GPTIMERS (general purpose timers)
• MISC. PERIPHERALS (other miscellaneous peripherals such as I2C, SPI and GPIO modules)

Section D: Analog Modules

Section D enables a configuration for analog modules in the AM35x as shown in Figure 5 below.

Figure 5. Section D of the AM35x PET Input Spreadsheet allows for the configuration of analog modules.

• VDAC (Video DAC) : On or Off
• USBPHY : Active or Standby

Spreadsheet Upload

Upon completion of the input spreadsheet, users can then upload the spreadsheet to TI for the power consumption analysis. Registration and legal agreement acceptance is required for the upload.

Upload your AM35x PET Input Spreadsheet here.

Power Analysis Report

Power Estimation Report Sheet

The power estimation tool generates a power analysis report is a spreadsheet format (See Figure 6). The estimated values are leakage, active and total average power over the time during the entire application scenario. It is also listed per power rail groups.

Figure 6. Power Estimation Report.

Power consumption in the AM35x device consists of:

• leakage power – due to leakage current, and dependent on temperature and power estimation mode; and
• active power – due to transistor switching, and independent of temperature.

The AM35x 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 AM35x that are performing some processing. Active power is independent of temperature, but dependent on voltage and module activity levels.

Module Utilization Sheet

The available bandwidth for each module depends on the device interconnects architecture. The power estimation tool calculates current module bandwidth from utilization entered by user and shows the results for each time slot with the maximum available bandwidth in separate sheet (See Figure 7).

Figure 7. Maximum Module Utilization.

Important Notes and Limitations

The following notes and limitations apply to the AM35x Power Estimation Tool:

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

References

1. AM35x Power Estimation Spreadsheet ([1]).

Revision History

Date	Modification
1/6/11	Version 1.00. Initial version.