Neo 1973 GTA01 Power Management
From Openmoko
In progress: This article or section documents one or more features whose implementation are in progress. |
This page details the power management 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. (See also Power management requirements.)
This is very much unimplemented at the moment.
Update: The standby mode works most of the time, and the wake-up-from-call functionality works, too. Some settings need to be changed. For details, have a look here.
Current projects:
User | Project | details | URL |
---|---|---|---|
cesarb | Cpufreq | Varying clock speed, including making peripherals work over during transitions |
User:CesarB/cpufreq |
Option | Note | Average saving over next lowest power state the description is the total effect on battery life |
Status |
---|---|---|---|
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 | Moderate(50mW) | Not implemented, limited by PMU to .3V steps |
CPU Idle mode | Turn off CPU clock while rest of SoC remains awake | Large(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. | Moderate (50mW) | Not implemented |
Option | Note | Saving | Status |
---|---|---|---|
General speed optimization 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.
Contents |
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:
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 | ||
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(seems to work at 50Mhz according to u-boot pll set) or 32Mhz (min variable CPU speed) | |
PLL | ?mW | Phase locked loop, needed if not in slow mode. | ||
Serial | 7mW | 2/3 integrated serial ports |
System design considerations
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
PCF50606 PMU
This is an overview of the PCF50606 power modes / state transitions
NOPOWER
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
SAVE
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.
STANDBY
Condition: Vbat > Vverylowbat
Human-readable: If main battery voltage > 2.7V
ACTIVE
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)
JBT6K74 LCM
Deep Standby
In this mode, only the supply power is activated
Sleep
Holds register data with clock stopped
Normal
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 management, we need to introduce state definitions with their according state names. The state names are prefixed by SYS_POWER_.
Name | Note | PCF50606 PSU chip |
S3C2410 CPU |
JBT6K74 LCD driver |
GSM | GPS | Bluetooth | Backlight |
---|---|---|---|---|---|---|---|---|
NO | No main battery or USB charger. Backup battery operational | Save | Off | PMU off | Off - no Vbatt | PMU off | PMU off | off |
OFF | "Switched Off" - no functionality | Standby | PMU off | PMU off | Off by MODEM_ON to LOW | PMU off | PMU off | off |
SLEEP | Suspend-RAM (in pocket waiting for a call) | Active | Power_Off | PMU Off | On by MODEM_ON to HIGH | Optional | Deep Standby | Off |
SCRSAVE | Screen Saver | Active | SLOW, IDLE | SLEEP | On by MODEM_ON to HIGH | Optional | Optional | Off |
ON | Normal active state | Active | On | Normal | On by MODEM_ON to HIGH | Optional | On | On, PWM'd brightness |
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
Implementation
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.
GPIO from Bluetooth
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.
BT_EN of the DFBM-CS320 is connected to GPB5 if the s3c2410. [1]
Button Press
If somebody pushes either the Neo1973 Aux Button or the Neo1973 Power Button, the system shall wake up.
Implementation
Power Button
During suspend, the PMU is configured to allow PWRONF events to generate interrupts to the CPU. (This is if PWR_IRQ is the internal signal from the PMU, mentioned in gpio.txt)
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.
Implementation
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! |
Voltages
NOTE: This section reflects the wiring of power rails in GTA01Bv04 |
VB
- Battery terminal voltage
- Used by
CORE_1V8
- This is the S3C2410 Core Voltage
- Generated by PMU DCUD
- Used by
- S3C2410 (vddiarm/vddi/vddi_mpll/vddi_upll)
STBY_1V8
- Standby Voltage for S3C2410
- Generated by PMU D3REG
- Used by
- S3C2410 (vddalive/rtc)
IO_3V3
- Generated by PMU DCDE
- Used by
- lots of pullups
- U1502 (latch for GSM UART)
- S3C2410 VDDMOP
- S3C2410 VDDOP
- S3C2410 VDDA_ADC
- S3C2410 nBATT_FLT
- S3C2410 !EXTCLK
- SDRAM_VCC3
- FLASH_3V3
- LM4857 Amplifier (i2cvdd)
- Vibrator
- Touch panel transistors
- SD_3V3 via U7501
- PMU (avdd)
GL_1V5
- Generated by PMU DCDF
- Used by
- AGPS (vdd_core)
GL_2V5
- Generated by PMU D2REG
- Used by
- AGPS (vdd_pllreg)
GL_3V3
- Generated by U7602
- Used by
- AGPS (vdd_io/vdd_lpreg)
- AGPS (X7601 -> rtcclk)
- Controlled by
- EN_AGPS3V3 GPIO
AVDD
3V
- Generated by U7602
- Used by
- AGPS (lna power int/ext, antenna switch)
- Controlled by
- EN_AGPS3V GPIO
CODEC_3V3
- Generated by PMU IOVDD
- Used for
- Audio Codec (digital and analog)
BT_3V15
- Generated by PMU D1REG
- Used by
- Bluetooth Module
LCM_3V3
- Generated by PMU LPVDDD
- Used by
- Headset/GSM Uart Latch
- LCM
FLASH_3V3
- Derived from IO_3V3
- Used by
- NAND Flash
SDRAM_VCC3
- Derived from IO_3V3
- Used by
- SDRAM
SD_3V3
- Generated by U7501
- Used by
- microSD slot
- Controlled by
- SD_ON GPIO
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 figures 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
- 150mW with backlight at full brightness
- 15mW with backlight at 10%
- 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.
- RAM 600mW at 600Mbytes/sec, power use broadly proportional to transfer rate.
- 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, 45mW
- Active on a call - up to 600mW, closer to tower less.
- GPS
- 45mW
- Rough measurement
- 45mW
Frequency(Mhz) | Notes | QVGA LCD | VGA LCD | USB device |
---|---|---|---|---|
12 | Slow mode | No | No | No |
12-33.74 | Impossible or violates PLL spec | |||
33.75-67.5 | Yes | No | Yes (with proper setting of HCLK divider) | |
79-266 | Yes | Yes | Yes | |
268-300 | Overclocking | ? | ? | ? |
Recommended clock speeds: 12 33.75 45 48 50.7 56.25 67.5 79 84.75 90 101.25 113.0 118.5 124.0 135.0 147.0 152 158 170 180 186 192 202.8 266 268 270
Other clock speeds are possible (in the 33.75-266Mhz range) by setting the PLL, however, the datasheet strongly recommends these, and recommends contacting samsung for speeds not listed above.
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.
The lowest power state I have gotten the Neo1973 phase-1 to run in is 90mA or so, for a life of some 12 hours. This is with backlight, GSM modem, bluetooth, GPS, off, the CPU clocked at 100Mhz, and undervolted to 1.8V, connected over usb-net (not powered via USB)
8 hours playing mp3 at moderate volume. (same caveats as above.)
Measured power draw on phase 0 neo1973
I played with old ampermeter, old nokia 3110 (as a power supply) 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.
Discharge graph
JoSch did a graph of battery volt versus time that can be found here.
Logging battery parameters to troubleshoot charging
WARNING
After installing and starting this script my Neo battery went flat in < 1 hour. Previously it was fine even overnight. If your battery is so flat that the Neo will not boot then leave it plugged in to a USB port for 15-20 minutes before powering up.
Some neos have managed to discharge their battery down to empty while off, plugged in, and supposedly charging from a 500ma-capable usb device. In order to help figure out how the state of charge changes while charging, running of battery, sleeping on battery, and sleeping while connected to usb, download two scripts in http://wile.org/stuff/power.tar Put the power-watch script in /usr/local/bin/ and the powerlog script in /etc/init.d, then
# ln -s ../init.d/powerlog /etc/rc5.d/S15powerlog
so that it starts up with the neo.
The script logs the time, battery voltage, charging current, battery temperature, charging mode, bluetooth-on status, gps-on status, gsm-on status, and backlight brightness numbers. The kernel page claims the charging current is in ma, but that does not appear to be the case for all builds? eg 2.6.21.6-moko10. The battery temperature does not always appear to be in degrees C, either.
After a few runs we can calibrate volts-to-remaining power, and then estimate off or sleep current draw and charging rate by observing the power drop [or rise] vs time between successive os boots.