hey i have to give a presentation about the working of microcontroller in train announcement system . i just have a block diagram which has a buzzer,rf cardreader and a voice chip interfaced to 8051. does anyone have the circuit diagram or detailed explaination or the source code for it, it would help me a lot. (this is the announcement system used in trains to announce the next station to the passengers inside the train and not the one used in platforms)