Editing N900 Hardware USB

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====USB battery charger====
====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 [http://focus.ti.com/docs/prod/folders/print/bq24150.html bq24150] 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.
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 200mA)  
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 200mA)  
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There is no published datasheet for this chip. It may be available under another name.
There is no published datasheet for this chip. It may be available under another name.
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A reasonably similar chip (compare chips: [http://www.ebv.com/fileadmin/products/Products/ST-Ericsson/Flyer_USB_Transceivers_1.pdf]) is the 1704 which has a datasheet [http://www.stericsson.com/technical_documents/CD00222700.pdf]  
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A reasonably similar chip (compare chips: [http://www.ebv.com/fileadmin/products/Products/ST-Ericsson/Flyer_USB_Transceivers_1.pdf]) is the 1704 which has a datasheet [http://www.stericsson.com/technical_documents/CD00222700.pdf]
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Another equivalent chip seems to be the https://www.startpage.com/do/search?query=FUSB2500 - see http://talk.maemo.org/showthread.php?p=643577#post643577
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For more information see [[N900 Hardware USB PHY]]
For more information see [[N900 Hardware USB PHY]]
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* The SoC has the USB protocol controller - this is the 'high level' controller - it implements most of the USB protocol. This is a [http://www.mentor.com/products/ip/usb/usb20otg/ Mentorgrafix MUSBMHDRC-core] IntelectualProperty function block licenced for the OMAP.
* The SoC has the USB protocol controller - this is the 'high level' controller - it implements most of the USB protocol. This is a [http://www.mentor.com/products/ip/usb/usb20otg/ Mentorgrafix MUSBMHDRC-core] IntelectualProperty function block licenced for the OMAP.
* The PHY (physical layer) chip connects to the world through the USB socket. This is not the normal companion chip - but the NXP part, and is connected to the SoC via a standard ULPI interface. It does the very lowest level USB hardware protocol. Also it detects chargers (by sensing D+/D- short). It also has a connection to VBUS, via a 1k resistor, to do certain probing.
* The PHY (physical layer) chip connects to the world through the USB socket. This is not the normal companion chip - but the NXP part, and is connected to the SoC via a standard ULPI interface. It does the very lowest level USB hardware protocol. Also it detects chargers (by sensing D+/D- short). It also has a connection to VBUS, via a 1k resistor, to do certain probing.
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* The [[N900 Hardware Battery Charger|bq24150a Battery charger]]. This is connected to the battery, and the PHY chip, as well as to the SoC though I2C. It handles (with the PHY chip) charging from dead. It also implements boost mode, to enable powering things through the USB socket. Of course it detects when external VBUS is applied.
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* The [[N900 Hardware Battery Charger|bq24150 Battery charger]]. This is connected to the battery, and the PHY chip, as well as to the SoC though I2C. It handles (with the PHY chip) charging from dead. It also implements boost mode, to enable powering things through the USB socket. Of course it detects when external VBUS is applied.
* Gaia. The [[N900_Hardware_Power_management/I2C|TWL4030]] is used to sense the value of the ID pin. It also has a connection to VBUS, to power up the device on charger insertion and inform a running system about changes in VBUS state. Though TWL4030 has a function similar to PHY chip as well, the original design using this function had to change as early chip revisions had problems with charger detection (so the rumour). Driver sourecode is full of cruft from that original design.
* Gaia. The [[N900_Hardware_Power_management/I2C|TWL4030]] is used to sense the value of the ID pin. It also has a connection to VBUS, to power up the device on charger insertion and inform a running system about changes in VBUS state. Though TWL4030 has a function similar to PHY chip as well, the original design using this function had to change as early chip revisions had problems with charger detection (so the rumour). Driver sourecode is full of cruft from that original design.
===The Software===
===The Software===
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* [[N900 Software BME|BME]] - the battery managment entity. This has its hands in everything, especially the bq24150a, and is split into
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* [[N900 Software BME|BME]] - the battery managment entity. This has its hands in everything, especially the bq24150, and is split into
** charger detection (via PHY) in kernel MUSB_HDRC driver, exposing /sys/devices/platform/musb_hdrc/charger
** charger detection (via PHY) in kernel MUSB_HDRC driver, exposing /sys/devices/platform/musb_hdrc/charger
** BME - userspace driver for the charger chip, as well as monitoring battery voltage through Gaia.
** BME - userspace driver for the charger chip, as well as monitoring battery voltage through Gaia.
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{{main|N900 Hardware USB Socket}}
{{main|N900 Hardware USB Socket}}
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===Compatible devices===
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[[Category:N900_Hardware]]
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{| class="wikitable sortable"
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|+ Compatible USB devices
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|-
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! USB device name
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! Status
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! class="unsortable" | Additional information
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! Additional driver needed
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! class="unsortable" | Discussion link
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|-
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| Edimax EU-4207 || Working || no problems found || <code>no</code> || http://talk.maemo.org/showthread.php?t=66667
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|-
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| ZTE-AC2766 || Working || no problems || <code>no, uses usbserial.ko</code> || http://talk.maemo.org/showpost.php?p=1198785&postcount=13
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|-
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|}
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[[Category:N900 Hardware]]
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