tag:blogger.com,1999:blog-2322291048042453151.post8435574866842373962..comments2022-03-30T19:26:28.939-07:00Comments on Hands On - Arduino: Project 4 - Interactive Traffic LightsJames Floyd Kelly (Jim)http://www.blogger.com/profile/13876934942928389738noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-2322291048042453151.post-15838248801413795152011-01-26T18:00:48.311-08:002011-01-26T18:00:48.311-08:00Jim,
You'll find that Analog GND and digital ...Jim,<br /><br />You'll find that Analog GND and digital GND are separated as they have been designed for different signal types and hence different noise characteristics. Digital 'expects' 0V and 5V (in reality I think the Atmel has anything under 1.3V as LOW) whereas the analog can expect anywhere between 0V and 5V. In good circuit design they are brought back together at the power regulator.<br /><br />In an ideal world, it shouldn't matter, but when is the world ever ideal :)<br /><br />Resistors above or below the LED's won't matter at all, they both experience the same amount of current.<br /><br />cheers<br />damoDamien Keehttps://www.blogger.com/profile/03945305185874524389noreply@blogger.comtag:blogger.com,1999:blog-2322291048042453151.post-73603184083105701992011-01-23T17:12:04.269-08:002011-01-23T17:12:04.269-08:00That's a nice trick with using a single resist...That's a nice trick with using a single resistor to make the ground connection... will have to remember that.<br /><br />Glad to hear the two GND pins on the Arduino are the same thing... makes me wonder why they did that (taking up a pin that could also have been used for something else).<br /><br />BTW, if you happened to have done Exp 33 or Exp 36 in the Make: Electronics book and took any photos or videos, please let me know... I'd love to be able to share them on the other blog.James Floyd Kelly (Jim)https://www.blogger.com/profile/13876934942928389738noreply@blogger.comtag:blogger.com,1999:blog-2322291048042453151.post-2113996780628512042011-01-23T09:10:15.043-08:002011-01-23T09:10:15.043-08:00Ground is ground I put my meter on it to see for s...Ground is ground I put my meter on it to see for sure. There is continuity between all the ground pins.<br /><br />I was short on resistors (too lazy to dig through the resistor box more truthfully) when I did this one, but from having done Mr. Platt's (Experiment 18), I knew I could get around that by connecting my ground rail to the Arduino's ground via a single resistor (I used 1K). Then I just connected all the cathodes to the ground rail and wired the pins to the anodes.<br /><br />This made the circuit faster and easier to wire, but it's not, I am told, best practice because when more than one of the LEDs is on, they appear slightly dimmer as did the 7 segment displays in Platt EX 18. Still when working within the limited confines of the breadboard, sometimes it's worth it to save a bit of space.<br /><br />I have one of the little prototyping shields as you mentioned, but I didn't like it so much for the experiments in this book. I like to build a circuit, then move an inch or so down the board and build the next one, leaving the first intact.<br /><br />So I bought a new breadboard for my Arduino experiments and I mounted it, and the Arduino to a strip of pegboard that I cut down to 10" x 3". I bought some 6" and 12" jumpers from Sparkfun, so I can easily connect a circuit to the Arduino even if it's at the far end of the breadboard.ctdahlehttps://www.blogger.com/profile/03301494095196099233noreply@blogger.com