Samsung S2 circuit - Page 1
Forum section: electronics / projects

author: awais
author_rank: Contributor
timestamp: September 18, 2017, 08:28:05 am
content: I am currently working used with a samsung S2 for my thesis. The work is to find energy used by the different operations by the smartphone. Can anyone guide me at which terminal of the battery should i connect the resistor.

author: rs20
author_rank: Super Contributor
timestamp: September 18, 2017, 08:37:20 am
content: Which resistor? A current-sensing shunt resistor? What are you using to perform your measurements?

author: awais
author_rank: Contributor
timestamp: September 18, 2017, 08:42:20 am
content: A 1 ohm resistor to find out the voltage and then calculate the current used by a single network operation.

author: randsl
author_rank: Contributor
timestamp: September 18, 2017, 01:45:01 pm
content: Please see the block diagram of the setup which is required for your measurements.Ammeter, multimeter is not suitable for this measurement as there's fast changes in current and these slow meters there's no way to capture fast transients.You need to connect an oscilloscope as shown in the attached diagram.Find the + & - terminals of the battery and you'll need to solder wires to the battery to keep it away from the phone...use a resistor < 10 ohms. you need to measure the exact value of the resistor with a multimeter to calculate the accurate current.Capture the voltage waveform as per your requirement. Then use I = V/R to calculate the current. You can measure battery voltage and use it to calculate the power.DO NOT power the mobile phone from a bench power supply which is powered from mains as it'll create short circuit to battery + to ground via scope ground terminal which can cause a DISASTER... Also better not to connect mobile phone charger when the oscilloscope is connected to the setup.

author: awais
author_rank: Contributor
timestamp: September 18, 2017, 05:41:15 pm
content: The multi meter that i am using se the has 3 sample unit i.e 3 values per second so can i use the ot.mulitmeter or n

author: randsl
author_rank: Contributor
timestamp: September 18, 2017, 11:43:57 pm
content: No You can't use the multimeter to get accurate readings. It'll show some indications of increase of the power consumption when the phone is drawing higher current for a long period of time.Most often, there are very short spikes of high current consuming phases in the operation. You can't see these short spikes as they last for only usec or msec period of time. So to see a true picture of power consumption, you must use a oscilloscope and record the voltage waveform and calculate the current.You said this is for your thesis. So you should ask to access an oscilloscope from your school/uni....

author: randsl
author_rank: Contributor
timestamp: September 19, 2017, 04:14:21 am
content: 3 Hz sampling rate (3 samples per sec) means, it captures data at 300 ms intervals.So there's no chance to see the variations occur in time periods less than 300 ms. As I mentioned in my previous post, most of the high power consumption operations lasts for a short period of time and if you use a multimietr, you wouldn't see the true picture of power/energy consumption at all...

author: randsl
author_rank: Contributor
timestamp: September 20, 2017, 06:44:33 am
content: If you use a oscilloscope for your measurements:see Dave's video :