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Return to Neo 1973 GTA01 Power Management.

Personal tools
In progress: This article or section documents one or more features whose implementation are in progress.

This page details the power managment of the Phase 1 Neo1973. Much of it is inapplicable to earlier models.

Power management is of utmost concern to any mobile device. Battery power is quite limited, so we need to make sure we try our best to conserve it.

This is very much partially implemented at the moment.

Required kernel mode power saving, and relative saving of battery life.
Option Note Average saving over next lowest
power state the description
is the total effect on battery life
External peripheral control Ability to dim backlight, turn on and off GSM, GPS, and other devices outside the CPU Huge (700mW) Implemented
Slow Mode The CPU clock is 12MHz, this is the lowest power mode with the CPU awake Huge(300mW) Not implemented
Variable CPU core voltage Dynamically alter CPU core voltage according to frequency Large(50mW) Not implemented
CPU Idle mode Turn off CPU clock while rest of SoC remains awake Moderate(150mW) Not implemented
Variable CPU frequency ~20Mhz to 266Mhz Vary CPU frequency to lower power consumption. Huge(250mW) Not implemented
Tickless Kernel Remove periodic timer interrupts in kernel Modest(10mW?) Not implemented
Rapid Suspend-RAM Suspend CPU totally and resume when required in under 1s. Huge (50mW) Not implemented

Required user-mode power saving
Option Note Saving Status
General speed optimisation of all software With variable CPU clock, the less CPU needed, the less power. Moderate (Large with backlight off) In Progress
Smart turning off unused peripherals Interacting with kernel mode drivers to turn off bits the user isn't using Large
Seamlessly switching to 256 colour The LCD controller supports pallete mode. This would reduce memory bus traffic by a third. Small Of debatable value - only for P1 (?)

This page tries to describe the various power management features of the Neo1973 Hardware, their states, transitions, etc. First, we start by describing the power states of the individual hardware components. Then we look at it from a System Integration point of view.

S3C2410 SoC

The S3C2410 SoC section is an overview of the S3C2410 power states or modes and their capabilities. The S3C2410 has the following modes:

Power states for the S3C2410 SoC(CPU) including approx memory bus current
Mode Frequency Power consumption Wakeup sources Note
Normal Mode 33-266Mhz (around 50-335mW depending on speed) Awake
Idle Mode 33-266Mhz around 50-170mW depending on speed Any interrupt FCLK disconnected
Slow Mode 12Mhz 40mW Awake, can vary clock speed as desired on interrupts. CPU clock (FCLK), SDRAM, bus clocks set by 12Mhz crystal.
Power_off Mode off .2mW (@2V) GSM, buttons, touchscreen, charger/USB connect, low battery EINT[0...15], RTC Alarm Interrupt, nBATT_FAULT pin. SDRAM self-refresh, RTC powered.
Peripheral Power Note constraints
USB-H 1mW The USB host driver FCLK>?
USB-D 6mW The USB device driver PCLK>20Mhz
LCD driver 20(qvga)-80mW LCD driver HCLK>VCLK*4 (p386) VCLK(vga)=19Mhz VCLK(qvga)=4.75Mhz = CPU clock 80Mhz min or 32Mhz (min variable CPU speed)
PLL ?mW Phase locked loop, needed if not in slow mode.
Serial 7mW 2 integrated serial ports

System design considerations

Template:Fixme In order to fully support Power_off mode, we need to

  • Be able to switch off VDDi/VDDiarm/VDDi_MPLL/VDDi_UPLL separately from VDDalive, using a switch based on the PWREN signal

PCF50606 PMU

This is an overview of the PCF50606 power modes / state transitions


Condition: Vbat < Vverylowbat && Vback < Vlowback && Vchgvin < Vlowchg

Human-Readable: If main battery voltage < 2.7V and backup battery voltage < 1.3V and charger voltage < 2.7V


Condition: Vbat < Vverylowbat && (Vback > Vlowback || Vchgvin > Vlowchg)

Human-readable: If main battery voltage < 2.7V and at least backup battery voltage > 1.3V or charger voltage > 2.7V.


Condition: Vbat > Vverylowbat

Human-readable: If main battery voltage > 2.7V


Condition: Vbat > Vlowbat Human-Readable: If main battery voltage > 2.8V (configurable up to 3.4V) Transition from STANDBY to ACTIVE: If ONKEY button is pressed, or RTC Alarm, or EXTON or charger insert or pen-down by touchscreen (we don't use the PMU TS controller)


Deep Standby

In this mode, only the supply power is activated


Holds register data with clock stopped


Fully powered up and operational

System Level

This is a description of the system-level power management.

System Power states

In order to do system-level power managment, we need to introduce state definitions with their according state names. The state names are prefixed by SYS_POWER_.


In this state, there is no main battery and no USB charger voltage applied. However, the backup battery is supposed to be operational.

  • PCF50606: SAVE
  • S3C2410: unpowered
  • JBT6K74: unpowered by PMU
  • GSM: unpovered because no Vbatt
  • GPS: unpowered by PMU
  • Bluetooth: unpowered by PMU
  • Backlight: powered off


This is the regular, "switched off" state of the device. The device does not provide any functionality.

  • PCF50606: STANDBY
  • S3C2410: unpowered by PMU
  • GSM: Powered down by driving MODEM_ON to LOW
  • GPS: unpowererd by PMU
  • JBT6K74: unpowered by PMU
  • Bluetooth: Optionally powered by PNU, to allow bluetooth events to wake the CPU.
  • Backlight: powered off


This is the regular, "fully switched on" state of the device, during user interaction.

  • PCF50606: ACTIVE
  • S3C2410: NORMAL
  • GSM: Powered up by driving MODEM_ON to HIGH
  • GPS: Depending usage / configuration
  • Bluetooth: Depending usage / configuration
  • Backlight: on (brightness according to PWM)


This is the screen saver mode, if user doesn't interact with LCM for some time (SCRSAVE_TIMEOUT), default 30sec.

  • PCF50606: ACTIVE
  • S3C2410: SLOW or IDLE
  • GSM: Powered up by driving MODEM_ON to HIGH
  • GPS: Depending usage / configuration
  • Bluetooth : Depending usage / configuration
  • JBT6K74: SLEEP
  • Backlight: powered off


This is the power saving mode, if user doesn't interact with LCM within SLEEP_TIMEOUT after SYS_POWER_ON_SCRSAVE was entered, default 30sec.

  • PCF50606: ACTIVE
  • S3C2410: Power_off (this is the suspend-to-RAM state)
  • GSM: Powered up by driving MODEM_ON to HIGH
  • GPS: TBD
  • Bluetooth: Powered down by PMU
  • JBT6K74: Deep Standby
  • Backlight: powered off

Wake-up reasons

In the following events, we want the main CPU to be able to be woken up from Power_off (SYS_POWER_SLEEP) state:

Events from GSM

  • Incoming phone call
  • Incoming SMS
  • Loss of network signal

The GSM daemon configures the GSM Modem so as to wake the CPU when events happen.

The S3C2410 has the EINT0 pin of the S3C2410 connected to the GSM modem, which wakes it on configured events.

Events from Bluetooth

The bluetooth module supports waking the host CPU on some bluetooth events.


Template:Fixme Which disconnects the USB interface of the bluetooth module, which sends the wake signal?

PIO_2 of the DFBM-CS320 is connected to GPC7 of the s3c2410. PIO_5 of the DFBM-CS320 is connected to GPC5 of the s3c2410. [1]

Button Press

If somebody pushes either the Neo1973 Aux Button or the Neo1973 Power Button, the system shall wake up.

Power Button

During suspend, the PMU is configured to allow PWRONF events to generate interrupts to the CPU. Template:Fixme (This is if PWR_IRQ is the internal signal from the PMU, mentioned in gpio.txt)

The PMU IRQ is connected to EINT9, i.e. an interrupt source that cannot wake-up from Power_off mode!

Aux Button

The Aux button is connected the EINT6 pin, which can wake-up the CPU from Power_off.

This means that resuming on Aux button will work out-of-the-box

Charger Events

If a charger plug (or any other USB device) is connected, the device shall resume and update the battery [charger] status. Also, charger errors such as over/undervoltage, over/under-temperature shall be reported.


During suspend, the PMU is configured to allow EXTONR,CHGERR and related events to generate interrupts to the CPU.

In GTA01Bv4, the PMU IRQ is connected to EINT9.

NOTE: Up to GTA01Bv3, the PMU IRQ is connected to EINT16, i.e. an interrupt source that cannot wake-up from Power_off mode!



  • Battery terminal voltage
  • Used by
    • LM4857 Amplifier
    • PCF50606 PMU
    • LCM Backlight
    • U7607 AVDD regulator
    • U7608 VTXCO_2V8 regulator


This is the S3C2410 Core Voltage

  • Generated by PMU DCUD


  • Generated by PMU DCDE
  • Used by
    • Vibrator
    • FLASH_3V3 (see below)
    • Touch panel transistors
    • S3C2410 VDDA_ADC
    • S3C2410 VDDOP
    • S3C2410 VDDMOP
    • S3C2410 nBATT_FLT
    • U1502 (latch for GSM UART)
    • S3C2410 EXTCLK ???
    • SDRAM


  • Generated by PMU DCDF
  • Used by
    • AGPS
  • Controlled by
    • PMU

PM Driver

  • Switch on/off if GPS is used or not

Initial state

  • disabled by u-boot PMU initialization


  • Generated by PMU IOVDD
  • Used for
    • Audio Codec (digital and analog)
  • Controlled by
    • PMU Driver

PM Driver

  • mostly included in ASoC, right?
  • switch on, only if Audio path is required.

Initial state

  • disabled by PMU initialization in u-boot


  • Generated by PMU LPVDDD
  • Used by
    • Headset/GSM Uart Latch
    • LCM

PM Driver

  • check whether we really need to switch this off, since LCM has sophisticated PM features

Initial state

  • enabled by u-boot PMU initialization


  • Generated by PMU D1REG

PM Driver

  • has to be powered up before Bluetooth can be used
  • Bluetooth device automatically enumerates at bus

Initial state

  • disabled by u-boot PMU initialization


  • Generated by PMU D2REG
  • Used by
    • AGPS
  • Controlled by
    • PMU Driver

PM Driver

  • switch on only in case GPS is enabled

Initial state

  • disable by u-boot GPIO initialization


FIXME: no idea what this is for

  • Generated by PMU D3REG

PMU Driver

  • permanently disabled

Initial state

  • disabled by PMU initialization in u-boot


  • Derived from IO_3V3
  • Used by
    • NAND Flash
  • Controlled by
    • SD_EN GPIO

PM Driver

  • do we really want to switch it on/off before every flash access?
  • if we go to standby, IO_3V3 will be switched off, thus FLASH_3V3 is off, too

Initial state

  • on, enabled by u-boot GPIO initialization


  • Generated by U6707
  • Used by
    • AGPS
  • Controlled by

PM Driver

  • Switch on only if GPS enabled


  • Generated by U7608
  • Used by
    • AGPS
  • Controlled by
    • EN_GPS2V8 GPIO

PM Driver

  • enable only if GPS is used.

Initial State

  • disabled by u-boot GPIO initialization


  • Derived from IO_3V3
  • Used by
    • microSD slot
  • Controlled by
    • SD_ON GPIO

PM Driver

  • we don't want to switch this off while mounted, do we?

Initial state

  • probably disabled, unless somebody uses 'mmcinit' from u-boot
  • but we can't disable it without disabling NAND.
  • result: enabled by u-boot GPIO initialization

Kernel API

Userspace API

Approximate power draw of various subsystems

In P0 and P1 phones, the battery has a total of 1200mAh, at 3.6V. This is approximately 3500mWh, once power supply losses are taken into account. The figues below are estimates from datasheets.

These do not take into account the severe hardware bugs of phase 0 hardware, which severely affect power use.

  • LCD
    • 500mW with backlight at full brightness
    • 50mW with backlight at 10%
      • Based on rough measurements of P0 hardware.
  • CPU
    • 320mW @ 200MHz
    • 450mW @ 266MHz
    • 140mW @ 200MHz idle.
    • 50mW @ 12MHz (slow mode)
      • These include fudge factors for RAM and other systems, from the CPU datasheet.
  • Bluetooth
    • 63mW @ Tx Burst (file transfer, send)
    • 36mW @ Rx Burst (file transfer, receive)
    • 3.6mW @ Idle, beacon only
      • Based on the datasheets provided
  • GSM ?
    • Idle, but connected to network, probably 30mW (based on similar devices)
    • Active on a call - up to 500mW or so, perhaps considerably less if close to a tower.
      • Based on 2W radio on 1/8th of the time as it is in a full rate codec.
  • GPS
    • 45mW
      • Based on comparison with a broadly similar (though not as fully featured chip from Maxim

USB does not work in slow mode, nor does the LCD screen controller. However, the CPU can be slowed down to 60Mhz or so and they will still work.

As bluetooth is connected via an internal USB connector, this will not work in the slowest mode.

This would imply that with the CPU constantly on in low power mode, GPS and GSM blipping on and off, and display off, the worst case power consumption is probably around 70mW, leading to a battery life of 2 days. If the CPU is turned off, battery life rises significantly.

With everything on, playing video with sound, for example should get well over 3 hours. (500mW LCD + 320mW CPU + 200mW audio + 50mW GPS. 4.5Wh at 1.1W draw)

Both voltage and clock speed to the CPU core can be altered. Exactly how this will work with the hardware is yet to be determined. It is possible that it may be capable of playing MP3s with the CPU clock at 60Mhz. This would considerably extend battery to well over 10 hours. Optimistically >24 hours of mp3.

Measured power draw on phase 0 neo1973

I played with old ampermeter, old nokia 3110 (as a powersupply) and phase0 neo1973 a bit. It appears to eat 1.02 mW while powered off, 1.02W while booted (backlight on), ~0.51W while sleeping (with backlight on) and 1.4W while loading applications.