have u connected standard crystal circuit and power on reset circuit?
why u have changed motor? DC motor is perfect. stepper motor is not at all suitable for vibration alert.
u said u want to do communication?
my question is how? using built in UART?
if yes i will sey it is not possible using photo diode.
u have to use TSOP IR sensor and at the transmitter side you have to use 38 KHz squarewave oscillator.