Step 1:

Testing

Connect 5.2 ohm resistor to 5 volt power supply.

so that I=V\R, I = 5/5.2 =0.961 amps

Total power = V*I = 5*0.961 = 4.8 watts (u will get 45 C)

After connecting 5.2 ohm to 5 volt supply u can feel warm around the resistor. USE 2 watts Resistor... I used 1/2 watts and burnt it.

If you want to produce more heat then use 2 amp power bank and change the resistor to 2.7 Ohms (power = 10watts).

So connect two 10 ohm Resistors in parallel to make 5 ohm like shown in the image.

Attach the Resistor to the Coffee Cup and apply Thermal Paste.

Open the Power bank carefully you will find battery and DC-DC converter. You can also use the powerbank directly without opening it, but I did this to reduce the size.

Now test the Coffee cup by connecting two ends of the Resistor wires to Powerbank output through USB cable. You can feel the increase in temperature and connect IDT wireless Receiver to the Powerbank input. Now the battery can be charged using Wireless receiver. Now add a transistor switch (TIP 29) in between the powerbank output and resistors I.e cut the usb cable +vcc wire and attach collector of transistor to one end and emitter to other end of the cable so that the heater can be controlled by transistor base voltage.

Prepare the case for coffee cup, I used a Flask and attach the wireless receiver to the bottom of the case.

Stick the wireless Receiver to the bottom of the case and Connect powerbank to it.

Program LinkitOne to Control the Coffee cup using Bluetooth android app.

Attach the LM35 temperature sensor to A0 pin, Transistor base switch and Bluetooth antenna to LinkitOne.

Thus LM35 reads the temperature and send it to android app through Bluetooth. The LinkitONE gets the preset temperature from android app and control the Heating heating accordingly.

Upload the Code shown in Code\Software section.

You have made it successfully. It is ready for charging.

Place the Coffee cup on the wireless receiver to charge it.

Connect the Coffee cup with Phone using Bluetooth setting.

then open the Android App, press connect and select Coffee cup from the list.

Press Turn on button and see the magic.