We see in all today electronic devices like mobile a Visual battery charging indicator,that a graphical Container composed of bars that increases one by one when the battery is charged for long, and decreases one by one when the mobile is used for long time. I see the same thing laptop in every GUI operating system like windows and Linux. I am not sure whether i am posting in the right place, because this requires a System Programmer and Electrical Engineer. A Visual view of my Question is here:
http://gickr.com/results4/anim_eaccb534-1b58-ec74-697d-cd082c367a25.gif
I am thinking from long long ago , under what logic this works? How the Program is managed to Monitor the battery. I made a simple logic based on Amps-hour, that how much time the bar should increase when the battery is in charging mode.??? But that does not work perfectly for me. Also i read a battery indicator Android application source code of my fried, but the function he used were System Calls based on Andriod Kernel (Linux Kernel).
I need the thing from the scratch.... I need this logic to know............. Because i am working on an Operating system kernel project, which later on will need battery charging monitor.
But the thing i will implement right now is to show just percentage on the Console Screen. Please give me an idea how i can do it.... Thanks in Advance
Integrating amps over time is not a reliable way to code a battery meter. Use voltage instead.
Refer to the battery's datasheet for a graph of (approximate) voltage vs. charge level.
Obtain an analog input to your CPU. If it's a microcontroller with a built-in ADC, then hopefully that's sufficient.
Plug a reference voltage (e.g. a zener diode) into the analog input. As the power supply voltage decreases, the reference will appear to increase because the ADC only measures voltage proportionally. The CPU may include a built-in reference voltage generator that you can mux to the ADC, or the ADC might always measure relative to a fixed reference instead of rail-to-rail. Consult the ADC manual (or ADC section of micro controller manual) for details.
Ensure that the ADC provides sufficient accuracy.
Sample the battery level and run a simple low-pass filter to eliminate noise, like displayed_level = (displayed_level * 0.95) + (measured_level * 0.05). Run that through an approximate function mapping the apparent reference voltage to the charge level.
Display the charge level.
