We used for the first time an Arduino during lab this week. Thanks to several examples more and more complex, we understood the inputs and the outputs on the Arduino. It would be useful to finalize technical details concerning project feature. The goal of this lab was to blink LEDs with different programs and algorithms.

During this lab, one question about the 7 segments display has been asked. The question was the following: should we place a resistance on each LED or should we place only one resistance for all?

Of course, the resistances limit the current to protect the led but is it necessary to place it for each LED? If an only resistance is placed upstream of the LED, the light intensity of the LED will decrease following the number of led light. So, at most the number of LED will turn at least their intensity will be great. The current is fixed and divided by the closure of each segment. With the other situation, one resistance for each LED, the current is fixed on each circuit branch by the resistance guaranteeing a constant value of current; the leds will light up with the same intensity regardless the number of LED light

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