Editing N900 Hardware Power management

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The power managment on the [[Nokia N900|N900]] is very complex, and involves a large number of interacting systems.
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The power managment on the n900 is very complex, and involves a large number of interacting systems.
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==Hardware==
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=Hardware=
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The TWL4030 (to be precise the TWL5030B, see [http://people.openmoko.org/joerg/n900/images/n900_01.jpeg] aka TPS65950) has USB PHY, power managment and audio codec.
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===SoC===
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The USB PHY isn't used and is handled by the nxp1707a [http://www.spinics.net/lists/linux-usb/msg25167.html] See [[N900_Hardware_USB|more information on USB]]
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The System-on-a-chip is the main processor on the n900.
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It seems to be documented - not under this part number - at [http://focus.ti.com/docs/prod/folders/print/tps65950.html TIs website]
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This is the [http://focus.ti.com/docs/prod/folders/print/omap3530.html TI omap3430].
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For more information see [[N900 CPU]].
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===Gaia===
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A quick check indicates the I2C bus addresses match - see 13.3 in above datasheet.
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The TWL4030  is a TI companion chip to the SoC. For more information see [[N900 Hardware Chipset]]
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If this is the correct part, the following description applies:
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===USB battery charger===
 
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The [http://focus.ti.com/docs/prod/folders/print/bq24150a.html bq24150a] charger from TI is a flexible charger. It, along with the PHY chip - support charging without the intervention of the SoC when the system is charging from a completely dead battery. The PHY chip detects a charger (shorted D+ and D- pins) and the charger uses this information to charge more rapidly.
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The TPS65950 contains;
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* Power management
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** Several regulators - switched mode and LDO.
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* Audio codec
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** Five DACs, two ADCs
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** Several power amplifiers.
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** Microphone amplifiers
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* USB tranciever
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** Highspeed OTG compatible with integrated charge pump, and carkit support, designed for direct connection to the SoC.
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* an ac/USB charger
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* LED drivers
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* ADC
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** ADC can measure both input voltages to device, or voltages connected externally.
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* RTC
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* GPIO
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** This can support switches, keypads, ...
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=Software=
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It also features reverse boost mode - which enables power to be supplied to a USB device connected to the N900. (up to a limit of 200 mA)
 
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For more information see [[N900 Hardware Battery Charger]]
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[[Category:n900]] [[Category:n900_Hardware]]
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==Firmware==
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The CPU is designed to work intimately with the companion chip, in order to implement [http://focus.ti.com/general/docs/wtbu/wtbugencontent.tsp?templateId=6123&navigationId=12032&contentId=4609 SmartReflex].
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This [http://www.TI.com/ TI]s method of adjusting the voltage of various portions of the chip dynamically, in order to ensure the power delivered to the many separate sections of the chip is just sufficient to allow for the current needs.
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All parts of the CPU that are not immediately in use are powered down.
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The CPU has well over a dozen seperate functional blocks, each of which can be powered on/off seperately.
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This dramatically reduces power usage.
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==Software==
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{{main|N900 software power management}}
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[[Category:N900]]
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[[Category:N900 Hardware]]
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