Portable electronic devices capable of obtaining charging current value of charger and charging method thereof

A portable electronic device, comprising:

• a connector, comprising a first data pin and a second data pin;
• a processor, comprising:
• a first set of pins, receiving and transmitting a pair of differential signals conforming to Universal Serial Bus (USB) specification;
• a second set of pins, comprising an input pin and an output pin;
• and
• a detection pin coupled to the input pin;
• a first resistor coupled between the detection pin and a first voltage;
• and
• a selector, selectively coupling the connector to the first or second set of pins of the processor according to a switching signal,
• wherein when the processor detects that a first pin and a second pin of a charger are respectively coupled to the first and second data pins of the connector, the processor provides the switching signal to the selector, so as to couple the first data pin of the connector to the input pin of the second set of pins and the detection pin of the processor and to couple the second data pin of the connector to the output pin of the second set of pins of the processor, and to provide a second voltage different from the first voltage, to the second pin of the charger via the output pin,
• wherein when the first data pin of the connector is coupled to the input pin of the second set of pins and the detection pin of the processor, and the second data pin of the connector is coupled to the output pin of the second set of pins of the processor, and when the second pin of the charger is provided with the second voltage via the output pin of the processor, the processor obtains a resistance of a resistor coupled between the first pin and the second pin of the charger that corresponds to a power capability of the charger according to a voltage of the detection pin, and then obtains a charging current value of the charger according to the obtained resistance of the resistor of the charger.