i.MX35 Multimedia Power Consumption Under Linux

Freescale Semiconductor
Application Note
Document Number: AN3876
Rev. 0, 06/2009
i.MX35 Multimedia Power
Consumption Under Linux
by
Multimedia Applications Division
Freescale Semiconductor, Inc.
Austin, TX
This document describes the considerations for measuring
the current consumption of the i.MX35 System on a Chip
(SOC) in an embedded application under the Linux
operating system.
This guide is intended for users of the i.MX35 SOC in power
sensitive applications where the Linux operating system is to
be used.
For more information about GStreamer visit
http://gstreamer.freedesktop.org/.
© Freescale Semiconductor, Inc., 2009. All rights reserved.
1.
1.1.
1.2.
1.3.
1.4.
1.5.
1.6.
2.
A.
B.
C.
D.
Contents
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current Measurement Details . . . . . . . . . . . . . . . . . . .
Software and OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Media File Information . . . . . . . . . . . . . . . . . . . . . . . .
GStreamer Command Lines . . . . . . . . . . . . . . . . . . . .
Raw Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Peak Power Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
2
2
3
3
3
3
3
4
5
6
7
Overview
1
Overview
This application note presents a method for characterizing the real-time power consumption of the i.MX35
processor using the i.MX35 Product Development Kit (PDK) with the Linux operating system.
1.1
Method
To measure the power consumption of the i.MX35, various power supply voltages and currents are
measured for the i.MX35 during operation. Power consumption is calculated by summing the product of
the voltage and current for each power supply.
1.2
Test Setup
A pre-production i.MX35 PDK, also known as the i.MX35 3-Stack, was used as the measurement platform
for this application note. The version 1.1.2 CPU card had a production i.MX35 device on it, marked
PCIMX356AVM4B.
Four power supply series resistors for the Core, CPU IO, PLL and DDR supplies were removed from the
CPU card. Connection points were added to the resistor pads to allow the connection of external ammeters
in place of the 0.02 Ω series resistors. The schematic identifiers for the pre-production board for these
resistors are not given here. The corresponding resistor identifiers for the production CPU card are:
• R228 — Core
• R229 — CPU IO
• R270 — PLL
• R218 — DDR
The current for each of these four supplies was measured by connecting four bench ammeters to the CPU
card across the series resistor pads, one for each power supply. The voltage for each supply was measured
at the ammeter on the i.MX side. Figure 1 shows the connection diagram of a single ammeter and
voltmeter to series power supply resistor Rxx on the CPU card.
Power
Supply
CPU Card
Rxx
A
i.MX35
V
GND
Figure 1. Power Measurement Connection Diagram
i.MX35 Multimedia Power Consumption Under Linux, Rev. 0
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Results
1.3
Current Measurement Details
The use of multiple bench ammeters in place of the 0.02 Ω series resistors was chosen as the method for
this application note.
The design of the CPU card precluded separating out only the i.MX35 contribution to the DDR power
supply; therefore, there was no way to split the i.MX35 from the rest of the circuitry in the bus without a
layout change. As such, the DDR power consumption necessarily includes the contribution of four DDR2
memories (K4T51163QE-ZID5), two 74VCX163245MTD and one 74LVC4245APW in addition to the
i.MX35.
1.4
Software and OS
The scope of the power measurements for this application note is limited to multimedia codecs playing or
converting media files under the Linux operating system. The Linux kernel and root file system were built
from the internal source archive: 20090330_L2.6.26_4.0.0_MX37TO1.1.1_AV_ER6_sp_ww12_2009.
This particular source archive contained all the GStreamer codecs used. The root file system was built as
a JFFS2 file system. The build environment was Ubuntu 8.10 and had all current updates applied at the
time. The kernel and rootfs were loaded into the NAND flash of the PDK via the Freescale's Advanced
ToolKit version 1.66.
1.5
Media
The format details of the various audio and multimedia files used in this application note are contained in
Appendix A, “Media File Information.” The media files were played or converted using GStreamer, an
open-source multimedia framework under which the Freescale-optimized codecs are used as plugins. The
specific command lines for GStreamer used in this application note are in Appendix B, “GStreamer
Command Lines.”
1.6
Data Collection
For each media file/codec, the supply current of each power supply was monitored, visually averaged and
then recorded along with the corresponding supply voltage. The measurements were conducted with the
i.MX35 core running at 400 MHz and 532 MHz.
2
Results
Table 1 contains the calculated and summarized average power consumption of the i.MX35 for various
media files under Linux. All the raw current and voltage measurements are contained in Appendix C,
“Raw Data.” The power consumption is the summation of the calculated power of each power supply (the
product of the voltage and current measured for that supply).
Although as many as three significant figures appear to be presented in Table 1, the values should not be
considered as having more than two significant figures because of the visual averaging of the current
during the measurements.
i.MX35 Multimedia Power Consumption Under Linux, Rev. 0
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3
Media File Information
Table 1. Multimedia Average Power Consumption Summary
532 MHz
(mW)1
400 MHz
(mW)
MP3 Playback
315
297
31
29
1.8
WAV Playback
313
298
29
30
0.3
AAC+ SBR Playback
338
319
54
50
3.9
WMA Playback
315
298
31
30
1.5
WMA Pro Playback
322
300
38
32
5.7
WMA Lossless Playback
370
345
86
77
9.5
WMV/ASF Playback
455
424
171
156
15.7
MP4 (MPEG4+MP3) Playback
418
391
135
123
12.0
AVI (MPEG4+MP3) Playback
418
392
135
124
10.5
MP3 Record (File to File)
582
492
298
224
74.5
Idle (Nothing Running)
284
268
—
—
—
1312
—
—
—
—
Media Type
Peak Power by
Simulation2
Delta @ 532 MHz Delta @ 400 MHz
(mW)
(mW)
Difference
(mW)
1
DDR component is a combination of i.MX35 contribution plus all other 1.8 V devices (4xDDR2 (K4T51163QE-ZID5),
2x74VCX163245MTD, 1x74LVC4245APW).
2 The peak power is the summation of the maximum power by simulation for the individual modules of the i.MX35 at
532 MHz, which are tabulated in Appendix D, “Peak Power Data.”
The first two columns in Table 1 show the total power consumption of the i.MX35 for the four power
supplies measured. Although the actual contribution of the i.MX35 is lower than this number because the
layout of the CPU card precluded separating the i.MX35 from the other devices on that power supply rail,
the relative proportion of contribution to power is assumed to be constant. The second two columns are
difference between the power consumption calculated for each codec and the idle current when no codec
was active for each corresponding core frequency. Idle was considered to be the state when nothing from
the command line was executing and only the normal processes that regularly run in the background were
active. The last column is the absolute value of the difference between the delta measurements.
As would be expected, current consumption increases as a function of core frequency. In looking at the
difference column and the fact that only two significant figures should be considered, the contribution to
power consumption by all the codecs except MP3 recording is essentially the same (no difference is greater
than ~16 mW). The difference with MP3 recording is that it is not constrained to real-time output of audio
and/or video like the other codecs; all the other media played at normal real-time rates.
The last row in Table 1 is the maximum power consumption for the i.MX35 at 532 MHz, which is the
summation of the maximum consumption for each module in the i.MX35.
Appendix A
Media File Information
Table 2 contains the information for each media file used in the collection of the data for this application
note. The actual file names of the media files have been omitted.
i.MX35 Multimedia Power Consumption Under Linux, Rev. 0
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GStreamer Command Lines
Table 2. Media File Information
Media File
Information
MP3 Input File
MPEG Layer 3, Stereo, 44.1 KHz, 160 Kbits/sec
MP3 Output File
MPEG Layer 3, Stereo, 44.1 KHz, 128 Kbits/sec (output of MP3 record)
WAV File
16-bit integer (little endian), Stereo, 44.1 KHz, 1.41 Mbits/sec, 16-bits/sample
WMV/ASF File
Audio: WMA2 codec, Stereo, 44.1 KHz, 48 Kbits/sec, 16-bits/sample
Video: WMV1 codec, 320x240 resolution
MP4 File
Audio: MPGA codec, Stereo, 44.1 KHz, 1411 Kbits/sec, 16-bits/sample
Video: MP4V codec, 320x240 resolution, 29.97 fps
AVI File
Audio: MPGA codec, Stereo, 12 KHz, 160 Kbits/sec
Video: MP4V codec, 320x240 resolution, 30.00 fps
WMA Pro File
WMAP codec, Stereo, 48 KHz, 128 Kbits/sec, 16-bits/sample
WMA Lossless File
WMAL codec, Stereo, 48 KHz, 1152 Kbits/sec, 24-bits/sample
WMA File
WMA2 codec, Stereo, 48 KHz, 192 Kbits/sec, 16-bits/sample
AAC SBR File
MP4A codec, Stereo, 44.1 KHz, AAC extensions SBR+PS
Appendix B
GStreamer Command Lines
Below are the GStreamer command lines and pipes used to play each media file type. The actual file names
used have been omitted.
MP3 Playback
gst-launch filesrc location=filename.mp3 ! mfw_mp3decoder ! alsasink
WAV Playback
WMV/ASF Playback
gst-launch filesrc location=filename.wav ! wavparse ! alsasink
gst-launch filesrc location=filename.wmv ! mfw_asfdemuxer
name=demux demux. ! queue max-size-buffers=0 ! mfw_wmvdecoder
! mfw_v4lsink demux. ! queue max-size-buffers=0 !
mfw_wma10decoder ! alsasink
AAC+SBR Playback
gst-launch filesrc location=filename.aac ! mfw_aacdecoder ! alsasink
WMA Playback
gst-launch filesrc location=filename.wma ! mfw_asfdemuxer !
mfw_wma10decoder ! alsasink
WMA Pro Playback
gst-launch filesrc location=filename.wma ! mfw_asfdemuxer !
mfw_wma10decoder ! alsasink
WMA Lossless Playback
gst-launch filesrc location=filename.wma ! mfw_asfdemuxer !
mfw_wma10decoder ! alsasink
MP4 (MPEG4+MP3) Playback gst-launch filesrc location=filename.mp4 ! mfw_mp4demuxer
name=demux demux. ! queue max-size-buffers=0 !
mfw_mpeg4decoder ! mfw_v4lsink demux. ! queue max-size-buffers=0
! mfw_mp3decoder ! alsasink
AVI (MPEG4+MP3) Playback gst-launch filesrc location=filename.avi ! mfw_avidemuxer
name=demux demux. ! queue max-size-buffers=0 !
i.MX35 Multimedia Power Consumption Under Linux, Rev. 0
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5
Raw Data
mfw_mpeg4decoder ! mfw_v4lsink demux. ! queue max-size-buffers=0
! mfw_mp3decoder ! alsasink
gst-launch filesrc location=filename.wav ! wavparse !
mfw_mp3encoder ! filesink location=output.mp3
MP3 Record (File to File)
Appendix C
Raw Data
The raw voltage and current data for each media file, power supply, and core frequency is shown in
Table 3.
Table 3. Raw Data
532 MHz
Media Type
MP3 Playback
WAV Playback
WMV/ASF Playback
AAC+ SBR Playback
WMA Playback
Power
Supply
400 MHz
Voltage
(V)
Current
(MA)
Power
(mW)
Total
(mW)
Voltage
(V)
Current
(MA)
Power
(mW)
Total
(mW)
Core
1.33
80
106
315
1.22
73
89
297
DDR1
1.8
79
145
1.8
79
145
CPU IO
3.3
12.3
40
3.3
12.4
41
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
80
106
1.22
75
92
DDR1
1.8
78
143
1.8
78
143
CPU IO
3.3
12.4
41
3.3
12.4
41
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
140
186
1.22
130
159
DDR1
1.8
110
201
1.8
108
198
CPU IO
3.3
13.5
44
3.3
13.6
45
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
96
128
1.22
89
109
DDR1
1.8
80
146
1.8
80
146
CPU IO
3.3
12.4
41
3.3
12.4
41
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
80
106
1.22
75
92
DDR1
1.8
79
145
1.8
78
143
CPU IO
3.3
12.4
41
3.3
12.4
41
PLL
1.4
16.2
23
1.4
16.1
23
313
455
338
315
298
424
319
298
i.MX35 Multimedia Power Consumption Under Linux, Rev. 0
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Peak Power Data
Table 3. Raw Data (continued)
532 MHz
Media Type
WMA Pro Playback
WMA Lossless Playback
MP4 (MPEG4+MP3)
Playback
AVI (MPEG4+MP3)
Playback
Power
Supply
Voltage
(V)
Current
(MA)
Power
(mW)
Total
(mW)
Voltage
(V)
Current
(MA)
Power
(mW)
Total
(mW)
Core
1.33
85
113
322
1.22
77
94
300
DDR1
1.8
79
145
1.8
78
143
CPU IO
3.3
12.4
41
3.3
12.4
41
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
120
160
1.22
112
137
DDR1
1.8
80
146
1.8
79
145
CPU IO
3.3
12.4
41
3.3
12.4
41
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
120
160
1.22
110
134
DDR1
1.8
105
192
1.8
104
190
CPU IO
3.3
13.2
43
3.3
13.2
43
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
120
160
1.22
110
134
DDR1
1.8
105
192
1.8
105
192
CPU IO
3.3
13.2
43
3.3
13.1
43
PLL
1.4
16.2
23
1.4
16.1
23
1.22
201
245
MP3 Record (File to File) Core
Idle (Nothing Running)
1
400 MHz
370
418
418
1.33
245
326
DDR1
582
1.8
105
192
1.8
100
183
CPU IO
3.3
12.5
41
3.3
12.5
41
PLL
1.4
16.2
23
1.4
16.1
23
Core
1.33
61
81
1.22
54
66
DDR1
1.8
76
139
1.8
76
139
CPU IO
3.3
12.3
40
3.3
12.3
40
PLL
1.4
16.2
23
1.4
16.1
23
284
345
391
392
492
268
DDR current is a combination of i.MX35 contribution plus all other 1.8 V devices (4xDDR2 (K4T51163QE-ZID5),
2x74VCX163245MTD, 1x74LVC4245APW).
Appendix D
Peak Power Data
Table 4 shows the peak power numbers for the i.MX35 under worst case voltage and temperature
conditions. These values are derived from the i.MX35 with core clock speeds up to 532 MHz. Common
supplies have been bundled according to Freescale’s power-up sequence requirements. Peak numbers are
provided for system designers so that the i.MX35 power supply requirements are satisfied during startup
i.MX35 Multimedia Power Consumption Under Linux, Rev. 0
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7
Peak Power Data
and transient conditions. Freescale recommends that system current measurements be taken with
customer-specific use-cases to reflect normal operating conditions in the end system.
Table 4. Peak Power Data
1
Supply
Voltage
(V)
Peak Current
(mA)
Peak Power
(mW)
QVCC
1.47
400
588
MVDD_PVDD
1.65
20
33
NVCC_EMI1
NVCC_EMI2
NVCC_EMI3
NVCC_LCDC
NVCC_NFC
1.9
90
171
FUSE_VDD 1
3.6
62
223
NVCC_MISC
NVCC_CSI
NVCC_SDIO
NVCC_CRM
NVCC_ATA
NVCC_MLB
NVCC_JTAG
3.6
60
216
OSC24M_VDD
OSC_AUDIO_VDD
PHY1_VDDA
PHY2_VDD
USBPHY1_UPLLVDD
USBPHY1_VDDA_BIAS
3.6
25
90
Total
—
—
1321
This rail is typically tied to ground, it only needs a voltage if in-system fuse burning is needed.
i.MX35 Multimedia Power Consumption Under Linux, Rev. 0
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Document Number: AN3876
Rev. 0
06/2009
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