Archive for November, 2010

Windows Phone 7 on a Samsung Focus

November 29, 2010 Leave a comment

Notes and observations about the Samsung Focus hardware running Windows Phone 7.



The Samsung Focus uses a certain amount of electricity in order to operate.  In order to charge, the incoming rate needs to exceed the rate being consumed by the phone.  If it doesn’t then you will problems like your Samsung Focus “charging slowly”, or “not charging.”

Not all USB ports output the same amperage.  The USB spec dictates each port output 5 volts, but amperage is only guaranteed to be available up to 100 mA.  If the phone requires ~200 mA and you plug your phone into a laptop USB port outputting 100 mA, then the battery will still be drained even though the device’s battery icon shows it’s charging.  Bus-powered hubs (USB hubs on the front-side of a desktop or most USB ports on a laptop) will generally provide 100 mA.  Root hubs and self-powered hubs should be 500 mA.  Some wall chargers will output >500 mA which while they’ll charge the phone faster could damage the phone or battery—if your phone gets hot while charging this is a good indicator it’s too much amperage as it needs to dissipate a higher amount of power.

Additionally, not all USB cables are not the same.  Some thinner cables (such as those in cheap retractable micro-USB cables) might have issues carrying amperage and will start to overheat (get warm to the touch) which will increase resistance and reduce the load (increase charging times).

You can access the battery diagnostics mode on the phone to find detailed information on battery charge percentage.  In short, bring up the phone and call “##634#”.  When the next screen comes up with the ‘-‘ button on top, enter the code “*#2*#”.  The Debug Mode for Chg/Bat will have three pages.  The first page (with examples values from my device):

  • ADC
    • VBATT: ?
    • INCHG: Incoming charge (?)
      • 1: no charge
      • 51-52: plugged into the USB2.0 port on backside of desktop computer
    • THERM: ?
      • 178
    • TA (T/F): ?
      • False
    • USB (T/F): Whether the device is being charged via USB or not.
    • BAT ID:
      • 4 (no cable or not charging)
      • 5 (charging via USB cable to USB 2.0 port on backside of desktop)
  • MV
    • VBATT_MV (mV, millivolt): Battery voltage
      • On my phone, when charged to 100% and then unplugged from charger, this value went up to 4185 and then slowly dropped with some minor jumps up and down.
    • VCHG_MV (mV): ?
      • 65 mV when unplugged
      • 4677 mV when plugged into USB2.0 port on desktop
    • ICHG_MV (mV): ?
      • 8 mV when unplugged (reads 0 immediately after being unplugged)
      • 419 mV on my phone when charging via USB
    • DEG (C): temperature of the battery
      • 21 C on mine while indoors
    • Bat_PER (%): percentage of battery charge
      • 100 when battery is fully charged

Todo: determine electrical metrics (e.g. amps) used by Samsung Focus in various scenarios.

Todo: determine electrical metrics output by various charging devices.


Touch can be finicky on the Focus.

  • Sometimes doesn’t work when lying flat on a surface
    • Remedy: picking the phone up (or just moving it?) seems to generally help. Note: if the phone is being charged, some chargers will prevent the phone’s screen from working while being charged.
    • Update 4/20/2011: This should be fixed with the Samsung firmware (v2103.11.3.3) updates released in the March 2011 WP7 update. More info.
  • When being charged with certain wall chargers, touch doesn’t work but resumes when unplugged
    • Todo: determine specifics on which certain chargers are likely to do this
  • Doesn’t like to be operated when vibrating.  This can easily happen when mounted in a car on a phone arm like below and say your car vibrates when idling with the heater on.
    • CarPhoneMountArm
    • Remedy: Move the car arm to a location where the mount can rest against the dash or otherwise not be vibrating out in the open.  Wrapping your hand around the phone to operate it can also temporarily fix this, but not while you’re driving..
  • Screen surface has excess dirt/oil on it.  This can be registered as wayward presses and make the phone act wonky.
    • Remedy: Wipe the phone screen with a clean non-scratching material– like your shirt.