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Power Consumption

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Power Consumption

This is an excerpt of the full BUG power management document which can be found here.

Overview

The section shows the power consumption of different devices on the BUG system. It also shows the power usage of some applications and drivers. The result are +/- 1 mA accuracy.

Discrete Devices and Applications

This section gives the information of the current consumption on a device/applicaton. It does not cover every device on the BUG system.

The measurement was done on the R1.3 BUGbase, running

  • U-boot,
  • Kernel built on bug/branches/R1.4/qa Revision: 9670.
  • My rootfs on the SD card with no application running.
  • Bugnav module loaded
  • apm-emulation module loaded
  • handy link connected to the base with serial port and ethernet connection.
  • No BUGmodules plugged-in
  • No BUGbase LCD attached

The BUGbase boots up, initializes the on-board devices and loads bugnav and apm-emulation modules.

The kernel default initialization includes

  • Activate UART for all 5 ports (4 to module connectors and 1 to console).
  • Activate SPI
  • activate sensor
  • activate LCD serializer
  • activate USB H2 transceiver
  • activate USB OTG transceiver.
  • Enable AUDIO Codec
  • Power on to Marvell device and release Bluetooth

Idle is when there is no new applications launching.

The combined usage represents the total current consumption of the BUGbase.

Device usage indicates the current consumption of a particular device (sometimes, application), calculated by subtracting the idle usage before and after the device is disabled or enabled.



Configuration (8/19/09)

Combined usage (mA)

Device usage

(mA)

Idle

323


Power off WIFI/Bluetooth on R1.3 base (Marvell device)

277

46




Idle

323


Disconnect the Ethernet cable (PHY device)

286

37




Idle

323


Disconnect serial port (UART tranceiver)

321

2




Idle

323


Modprobe libertas_sdio (combination of WIFI device activated and libertas driver running)

422

99

wpa_supplicant (application – WIFI scan, rx and tx)

442

20




Idle

323


Reset Bluetooth device (bluetooth device)

317

6




Idle

323


Modprobe echi_hcd

modprobe bluetooth

modprobe hidp

modprobe l2cap

(Bluetooth activation + its drivers)

518

195

Hciconfig hci0 up

520

2

Hcitool scan (Bluetooth scan for other devices. This is only a momentarily event, but interesting to know)

546

26




Idle (Default BUGBase codec enabled)

323


Modprobe bug_audio (Codec is released from reset)

327

4

Disable Codec (Audio Codec)

316

7




Idle

323


Modprobe arcotg_udc (no USB otg plugged-in)

Enable the MX31 device controller

337

14

Modprobe g_ether (no USB OTG plugged- in)

337


Plug in USB OTG – USB transceiver

351





Idle

323


Disable USB H2 transceiver (USB H2 transceiver)

297

26




Idle

323


Disable USB OTG transceiver (USB OTG transceiver)

311

12




LCD Serializer 1 slot


10


Table 2 – Current Consumption on Different Configurations

R1.3 BUG with Production Rootfs


Using the same BUGbase as the previous section, the next table shows the current consumption of running the BUGbase using the BUG production rootfs.



On top of the basic kernel initialization, the production rootfs loads the following module drivers and launch applications after power up.


lsmod


Module Size Used by


rtc_isl12026 9856 0


rfcomm 37652 0


btusb 11736 2


libertas_sdio 13864 0


libertas 175612 1 libertas_sdio


firmware_class 8136 1 libertas_sdio


hidp 14304 0


l2cap 22212 10 rfcomm,hidp


bluetooth 63652 8 rfcomm,btusb,hidp,l2cap


g_ether 29140 0


ehci_hcd 45456 0


bugpm_apm 4632 0


apm_emulation 8092 2 bugpm_apm


bugnav 4228 1


bug_v4l2_capture 30872 0


bug_camera 6276 1 bug_v4l2_capture


bug_audio 17596 1


bmi_lcd_core 22116 0


arcotg_udc 22572 1 g_ether



Idle is when the serial port displays a log-in prompt sign and no new application starts.

In the test, I use ethernet over USB and connect the SDIO WIFI to an AP.



Configuration (8/19/09)

Combined usage (mA)

Device usage

(mA)

Idle (no module)

570-700


apm -s to suspend

192


Table 3. Current Consumption on a unit during idle and suspend (no module plugged-in)


Configuration (8/19/09)

Combined usage (mA)

Device usage

(mA)

Idle (no module)

570-700


LCD module plug-in

926-1000+


apm -s to suspend

192


Table 4. Current Consumption on a unit with LCD during idle and suspend (LCD module plugged-in


Configuration (9/3/09)

with Front plate LCD

Combined usage (mA)

Device usage

(mA)

Idle (no module)

wpa_supplicant connect to a wrong AP

770-820


Kill wpa_supplicant

690-715


wpa_supplicant – associates to a correct AP

700-730


Apm -s

92.6,


138,107


Front plate LCD backlight = ~3mA




R1.2 Base with Production Rootfs


The table below shows the R1.2 base current consumption.

Configuration:

  • U-boot,
  • Kernel built on bug/branches/R1.4/qa Revision: 9670.
  • Production ootfs on the SD card with no application running.
  • handy link connected to the base with serial port and ethernet connection.
  • No BUGmodules plugged-in
  • No BUGbase LCD attached
  • Ethernet over USB



Configuration (8/19/09)

Combined usage (mA)

Device usage

(mA)

Idle (no module)

556 - 564


Kill wpa_supplicant (wpa_supplicant consumption)

515 - 517

50mA

Table 5. Current consumption while running wpa_supplicant