Whats A Microcontroller v3
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Appendix B: More about Electricity · Page 341
I = I1 + I2 + ...Ii
I = 7.02 mA + 7.02 mA I = 14.04 mA ≈ 14.0 mA
Figure B-4
Total Current Supplied to Two LED Circuits
Your Turn – Modifying the Circuit
9Repeat the exercise in Figure B-2, but use Vin – Vss = 9 V instead of Vdd – Vss = 5 V.
Assuming the forward voltage does not change, the answer is VR = 7.3 V. The measured resistor voltage will probably be slightly less because of a larger LED forward voltage from more current passing through the circuit.
9Repeat the exercise in Figure B-3, but use a 1 kΩ resistor. Answer: I = 3.3 mA.
9Use VR = 7.3 V to do the exercise in Figure B-3 with a 1 kΩ resistor. Answer: I = 7.3 mA.
9Repeat the exercise shown in Figure B-4 with one of the resistors at 470 Ω and the other at 1 kΩ.
Answer: I = 7.02 mA + 3.3 mA = 10.32 mA.
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Appendix C: RTTTL Format Summary · Page 343
Appendix C: RTTTL Format Summary
This is a summary intended to help make sense out of RTTTL format. The full RTTTL specification can be found published at various web sites. With any search engine, use the keywords “RTTTL specification” to review web pages that include the specification.
Here is an example of an RTTTL format ringtone:
TakeMeOutToTheBallgame:d=4,o=7,b=225:2c6,c,a6,g6,e6,2g.6,2d6,p,
2c6,c,a6,g6,e6,2g.6,g6,p,p,a6,g#6,a6,e6,f6,g6,a6,p,f6,2d6,p,2a6 ,a6,a6,b6,c, d,b6,a6,g6
The text before the first colon is what the cell phone displays as the name of the song. In this case, the ringtone is named:
TakeMeOutToTheBallGame:
Between the first and second colon, the default settings for the song are entered using d, o, and b. Here is what they mean:
d – duration o – octave
b – beats per minute or tempo.
In TakeMeOutToTheBallGame, the default settings are:
d=4,o=7,b=225:
The notes in the melody are entered after the second colon, and they are separated by commas. If just the note letter is used, that note will be played for the default duration in the default octave. For example, the second note in TakeMeOutToTheBallGame is:
,c,
Since it has no other information, it will be played for the default quarter note duration (d=4), in the seventh octave (o=7).
A note could have up to five characters between the commas; here is what each character specifies:
,duration note sharp dot octave,
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For example:
,2g#.6,
…means play the half note G-sharp for 1 ½ the duration of a half note, and play it in the sixth octave.
Here are a few examples from TakeMeOutToTheBallGame:
,2g.6, – half note, G, dotted, sixth octave
,a6, – default quarter note duration, A note played in the sixth octave ,g#6, – quarter duration, g note, sharp (denoted by #), sixth octave
The character:
,p,
…stands for pause, and it is used for rests. With no extra information, the p plays for the default quarter-note duration. You could also play a half note’s worth of rest by using:
,2p,
Here is an example of a dotted rest:
,2p.,
In this case the rest would last for a half note plus a quarter note’s duration.
