2 tutorial questions, for understanding

by vnwnkl on Thu Jan 03, 2013 12:54 am

Hey just trying to figure out the reasoning for a few tutorials. I have been following the adafruit learning center stuff too and its made me rethink a few of the tutorials in the starter pack.

Question 1: Tutorial 1, led blinking (basic question) - theres a ground connection for the led through a resistor.. but what purpose does the 5v connection serve? the 5v is provided by the pin and the circuit is complete. this seems redundant.

Question 2: Tutorial 7, Buttons - there is a cable going to 5v, and the resistors on the buttons are connected to that rail, rather then the ground. the buttons are already connected to pins, so why are the resistors not connected to ground, and remove the 5v connection cable?

Really would like some help on this so I can move on! Thanks in advance :D
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Re: 2 tutorial questions, for understanding

by adafruit_support_bill on Thu Jan 03, 2013 6:38 am

its made me rethink a few of the tutorials in the starter pack.

Are you talking about the ARDX tutorials or the original Adafruit tutorials? If you can provide a link to the specific tutorial page it would help.

Not sure about Q1 - I'd have to see the circuit you are talking about. For Q2, pushbuttons should be wired with a pullup or a pulldown resistor. This resistor keeps the digital input state from 'floating' when the button contacts are open. See: http://www.ladyada.net/learn/arduino/lesson5.html
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Re: 2 tutorial questions, for understanding

by vnwnkl on Fri Jan 04, 2013 1:21 am

hey there

the tutorials were the ardx ones

ardx.org/BBLS01 for the first circuit
ardx.org/BBLS07 for the second circuit

i guess my question is if the pin provides the 5v, and the ground completes that circuit, why the need to provide the cables to the 5v pin on the arduino?

thanks again,
c
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Re: 2 tutorial questions, for understanding

by adafruit_support_bill on Fri Jan 04, 2013 6:41 am

In CIRC01, the anode connects to Pin13 only. The diagram is a little confusing there, but the LED does not connect to the 5v rail.

In CIRC07, the 10K resistors are pullup resistors as described in the link I posted earlier.
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