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p.6

RGB LED is controlled by the chip behind the R/G/B LED light. This LED doesn’t require resistor in circuit because it’s already embedded in the chip.

p.17

The power of the microcontroller is limited (V*I is limited). Thus, when it has to supply LED that needs a nice amount of current, the voltage drop from 5V, to a LED suitable current. (Which is lucky)

p.22 YOU GOT TO FIGURE THIS OUT

Because LED resistance change all the time, so in choosing resistor, look for the optimal “current” first (by experience, 1mA-5mA is nice for LED), then use the data sheet to find the voltage, then further calculate the resistance preferred.

The second way is just to simplified the calculation as the chart above, and assume the voltage desire is 2.1V. It’s not totally accurate but much faster.

!!!!

Ways of saving RAM space. If the data/array is const, you can use the “const” to save memory, and the data will be put into flash memory instead of RAM. The left one is theoretically faster, but not noticeable in such applications.

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Light guide!

p95 in diffusor means 95% of the light can go through.

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