Weekly Journal Multiplexers and Shift Resistors (Emily Smith)

This is a video of what we did in class on thursday. Both Tuesday and Thursday we followed along with Dr. Hamid as he went through the code. Using the schematic found on adafruit we set up the bread board, though ours looks slightly different because the LED’s are placed differently. The purpose of these activities were to explain the use of Shift Registers and multiplexers, both of which are used to decrease the number of digital input ports used. Shift Registers do this by directing the data in a different way like a train switcher turns around trains, the shift register shifts which pin it is communicating to. Unlike shift registers, multiplexers send the data in a down all pins. Benefits to this method are that they don’t require as many pins. Where every time the number of pins is doubled for a shift registers a new pin is used on the Arduino, multiplexers only ever use three pins. This is particularly helpful when having more than one output such as leds. One case that one might rather have a shift register is when there are more than one inputs such as buttons. The reason for this is that shift registers can read which ever button, but using a multiplexer for this means that you would have to wait for it to read all other inputs until you get to the one you need, which can cause a delay.


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