At this state all individual circuit were working and now it's time to connect them all together and testing them out. When connect all the circuit it is necessary to pay extra attention because if some connection between the pin or chips are not properly grounded will have a problem during operation. Based on my experience it is better to do it step by step and follow the schematic. And also check all connection as it goes. When it's all being connected then used since wave to check each chip's input and output so we know it is behaved as expected. When all the chip working as expected then we can use mp3 music player to send a music into the ADC, for this project we used iphone to play music then feed it into PCM encoder and then the output of the encoder will output digital data which then send into LED driver to transmit through fiber cable. And at the other end the receiver photodiode will receive the data been transmitted and then send it to PCM decoder and it will convert it back to analog signal. And then to play the music I'm going to use my computer to play back so the analog output of the PCM decoder will connect to audio interface and then the interface will connect to my computer and output the music. During this process I've encountered lot of problem such as wrong connection of the clock, LED driver (wrong calculation of resistor), lot of noise from LED transmitter and photodiode receiver and so on. The worse thing is identify the problem when the problem is identified then it can be easily solve but sometime a little bit difficult.
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