See the schematic below. Once you have the keyboard made, the rest is very easy. Just make the connections as below. Just be careful, upload the code from below before you connect the Tx and Rx wires from the keyboard. Otherwise the code won't upload. Connect the battery to the charger and the charger output to the sliding swith and that to 5V that will power everyting. The Radio module will be connected at 3.3V.
