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1  Using Arduino / Project Guidance / Re: Read car AC display using Arduino on: July 23, 2014, 10:19:48 am
Careful!  You are doing things that can damage your Arduino!

The acc wire that supplies 12V... yes, it could be used to power the Arduino, but you should be aware that it can be a "noisy" 12 volts and might have voltage drops or voltage spikes.  Others have written about this.  Not sure what the best advice is for this, but in theory it should work.  I think I've read of others putting a voltage regulator in between the 12V and the Arduino to help save the Arduino from battery weirdness.

Using a 5V voltage regulator to drop a 12V signal for sense detection on an Arduino is not a good idea.  It is a really, really bad idea.  You should not do that.  What you should do is use an optoisolator as a switch.  Have the 12V signal switch the optoisolator on/off.  Have a digital I/O pin on the Arduino connected to ground on the Arduino.  So when the 12V signal is there, the switch is on, and current flows from the digital I/O pin to ground.  When the 12V signal is not there, no current flows from the digital I/O pin to ground.  Your use of a voltage regulator is just plain wrong.  You do not want to add voltage to an Arduino's input pins from another voltage source.  They aren't designed to do that.  A voltage regulator will generate heat by burning off the excess voltage as... well... heat.  It is designed to power something - not for using as an input signal.  It might work, but it also might fry your Arduino.

The analog pins on the Arduino are only designed for 0 to 5V.  The value you are getting is NOT voltage.  The value is a range between 0 and 1023, which corresponds to 0 to 5V.  So if you read a value of 512, that would be approximately 2.5V.

As for what you suspect is a data wire...  It's not likely to be a compatible serial signal that you can just hook up to the serial pins on an Arduino.  You would need an oscilliscope or a digital probe that actually capture and analyze the highs and lows to figure out the signaling and protocol.  Not something you can do without one, unless you can somehow find the specs on the protocol used.  And even if it was a TTL serial or RS-232 or RS-485 signal, tapping into it with an Arduino could affect the signal and make it not work.

Is the fan knob a potentiometer with 3 wires?  If so, your  best bet might be to disconnect the fan knob from the AC unit and instead connect it to the Arduino to read, then use a digital potentiometer IC (like the DS1308 for example) to send a digitally controlled output to the AC unit.  This would also let you override the fan setting from the Arduino.
2  Using Arduino / Project Guidance / Re: How to drive lights with a text file on: July 14, 2014, 12:35:13 pm
You mentioned "Word document", which I take to mean Microsoft Word.  You're not going to get an Arduino to read that.  You will want to use a plain text file, aka ascii file.  How do you intend to "feed" the file to the Arduino?  SD card?
3  Using Arduino / Project Guidance / Re: custom PCB on: July 14, 2014, 12:31:07 pm
Some advice for the "tombstoning"...  (By the way, I assume you meant 0603, or 0805, not 0803).  Are you sure you are putting down the right amount of paste?  Too little can cause problems.  Are you putting down paste unevenly --meaning 1 pad has way more paste than the other pad?  That's where most of my tombstoning happens.  I personally don't use an oven - I do all my surface mounts with a hot air reworking station.  Uneven heating can lead to tombstoning too, so maybe take a look at how your oven is heating the boards?  Finally... there is a glue you can use to hold the parts in place.  I forget what it's called, but it's usually reddish in color.  I've never used it, but one little tiny tab of that between the pads will hold your resistors and caps in place and prevent the tombstoning during reflow.
4  Using Arduino / Project Guidance / Re: Help design a system on: July 02, 2014, 01:43:00 pm
I can't remember whether it's from one of the Iron Man movies or RoboCop, but I remember a scene when they were demonstrating a suit and it malfunctioned, ripping the driver's lower torso off and kill him.  Think that was Iron Man.

EDIT:  It was from IronMan 2.  Oh yeah, and according Justin Hammer, the test pilot survived.  Lol.
5  Using Arduino / Project Guidance / Re: does anyone know what kind of sensor is used in this application? on: June 23, 2014, 12:40:40 pm
Didn't you already post about this a few weeks ago, or was that some other person?  The sensor in the first photo is an untrasonic distance sensor, also commonly called a "ping" sensor.  It literally "chirps" an ultrasonic pulse out of one of the cans.  In theory, the pulse echos off an obstruction and is received back to the other can.  You typically count how long it takes for the pulse to come back, and from there it is a simple mathematical formula to calculate the distance.  These are commonly used for robots to help with collision avoidance or for anything where you want to attempt to measure the distance from something.  I've got some experience with them.  I don't think they will be a good sensor for you to use on your hoop machine.  First, they are prone to errors...  The sound radiates outward and pulses can be echoed off a wide range of things... the further out the pulse goes, the bigger the chance the pulse will echo off something not directly in front.  For example, I attempted to build a parking assistant for my garage.  The pulses were constantly bouncing off other things in my garage causing false distances.  Also, these don't work well if the surface they hit is curved or angled away.  They work best with the object they hit is flat and directly facing the sensor.  Case in point, my wife's car has a lot of curves on the front of it.  I could never get the sensor to report correct distances with her car, yet it worked fine with my car.

As I mentioned in the other thread, the best way to do this is with an IR proximity detector or IR break beam.  If you had it mounted just under the rim angled at a downward angle, this would probably eliminate false triggers.  The idea is there is an IR emitter that shoots infrared light that gets reflected back only if a ball is in the way.  Since the beam won't be reflected back until the ball is more than halfway in, you should be able to prove the ball is going through.  You're probably going to have to adjust the angle until you get it right.

Give this one a try:

Or this one:

6  Using Arduino / Project Guidance / Re: Counting Person entering a room on: June 23, 2014, 10:17:10 am
That's great that it works.  I guess either you've set the RSTDISBL bit to disable reset on PC6 or you're just lucky with PC6 floating.  I guess one way you could test that is to touch a wire between PC6 and GND for a few seconds and see if it resets.  Since this pin isn't connected to anything, you have a floating pin.  If you have not set the RSTDISBL bit, your chip could periodically reset itself.  Heck, it might be doing that right now without you even realizing it depending on how your sketch works.
7  Using Arduino / Project Guidance / Re: Another Orbit Yard Watering valve question. on: June 20, 2014, 02:52:03 pm
All my Orbit sprinkler valves are "jar-top" solenoid valves.  If I'm not mistaken, these valves are closed if no electrical current flows, and they open when power is applied.  Power in this case is low-voltage AC, I think 24 volts.   
8  Using Arduino / Project Guidance / Re: Counting Person entering a room on: June 20, 2014, 12:15:22 pm
You're also missing a pullup resistor on the reset line.  Without that, the chip will be stuck in reset mode.  Also, how are you going to program the chip?  Recommend you put in ICSP interface or at least breakout the RX/TX and reset pins so you can use a FTDI USB to serial interface to program an already boot-loaded chip.  Question... have you actually tried this circuit out on a breadboard to prove it works?  I'm guessing no, because there are a lot of things wrong with it.  Breadboard it first before you design your PCB.  Will help you figure out some mistakes.
9  Using Arduino / Project Guidance / Re: Counting Person entering a room on: June 20, 2014, 12:11:49 pm
Also, I don't see an external crystal, so I assume you are changing the fuse bits to use the internal oscillator?  Not sure if that's automatic.  I've always used an external crystal myself.
10  Using Arduino / Project Guidance / Re: Counting Person entering a room on: June 20, 2014, 12:05:45 pm
You might want to add a filter cap on the output of the 7805.  Your schematic is drawn a bit "funky".  Don't have traces going through the parts and don't have parts inside other parts.  Makes it difficult to read.  I also think you missed the ground connection on the HD44780.    Where is the trace off the right edge going to?  What voltage is your AC coming in as?  I'm assuming this is low-voltage AC, right? 
11  Using Arduino / Project Guidance / Re: Fish tank "entertainment" system. LEDs. on: June 20, 2014, 11:53:21 am
Search for "NeoPixels" on  These are RGB LED's that are available in strips, circles, and individual units.  They can be daisy chained together using only 3 wires and only 1 digital I/O pin.  Pretty easy to use and the example code is a great starting point.  Here's a video of two NeoPixel rings (the 16 segment versions) running off a Trinket:

12  Using Arduino / Project Guidance / Re: I want to make a 120v 8 outlet chasing Christmas light controller on: June 20, 2014, 10:45:23 am
I feel like I have a little bit of experience in this area, due to the following:
  • Wrote and sold a software product called LightShowMaster that used Insteon home automation technology for creating light shows.  See an example here:
  • Designed a prop controller called the MonsterShield for the haunted attractions / entertainment industry that uses AC relays which is sometimes used for light shows.
  • Own 48 channels of Light-O-Rama hardware

First, let me just say that you can use relays to do lightshows.  
As you know, relays are mechanical, and they can and will fail eventually.  I've been developing and selling my relay-based MonsterShield for several years now, and they've been used in several professional attractions around the world without failures (yet).  I've personally yet to have a single relay fail - and I've run a LOT of them for a long time and pushed them hard.  But, at some point I know that they WILL fail.  Well that's not entirely true...  I did have a relay fail on-site at a customer's location, but that wasn't due to normal use - the customer had screwed up and connected BOTH ends of AC to a relay, and it destroyed the relay.  The other 3 relays on the module were still fine.   The relay modules I use are from SainSmart, and they are pretty cheap in price and reasonably good quality, so replacing them is not an issue for me.  They have proper air-gap isolation and optoisolators.   Here's some eye candy for you:
Here's a video from one of my customers that used a MonsterShield with expander board and 16 relays:
And here's a test video I did with 2 MonsterShields and 32 relays:

SSR's are definitely the way to go if you want long-term reliability, and they also have the benefit of being quiet.  They are also usually a lot more expensive.  But hey, if you want the best, go with SSR's.  SainSmart makes some SSR boards but I haven't yet tried them.
If you want to do any kind of dimming, then neither SSR or relays are the way to go.  You'll have to do some high voltage work with Triacs, which I recommend you leave to the professionals.  If that's what you're after, you should just bite the bullet and go for Light-O-Rama or Animated Lighting or something similar.  You can also build your own, and there are plenty of websites devoted to that.  Check out the forums on and take a look at Vixen.

13  Using Arduino / Project Guidance / Re: Program ATmega328 Using Instruction Set on: June 18, 2014, 12:24:46 pm
Honestly I would go with the emulation route in the sketch.  I wouldn't touch the boot loader.  Would be a lot easier.  Won't be as fast in execution, since it will be interpreting opcodes in memory and executing lots of instructions per opcode, but it will be much easier to develop a working emulation.
14  Using Arduino / Project Guidance / Re: My Tide Vane Project on: June 18, 2014, 08:27:44 am
Yeah, I'd just use 3 single dimension arrays.  I would also recommend not doing all those copies when you get a new data element so that the old one "rolls off".  A better way is to use an index that points to the last row used.  Each time you write a wrote, you increment the index.  And if you increment the index past the end, you'll have to reset it to the beginning (usually 0).   This way you're just overwriting the oldest entry and not doing all those copies. 
15  Using Arduino / Project Guidance / Re: Switching USB on and off on: June 18, 2014, 08:21:25 am
The FTDI-based chips, cables, and related solutions use a certified USB driver... Windows 7 seems to download and install this automatically -- at least it did on my computer.  You can also download the driver directly from FTDI's website.  Once it's installed, you shouldn't ever have to install it again.  As the other person said, the IDE won't need to know anything about the driver - the IDE just uses a COM for communication, which is what the FTDI driver provides.  And yes, you can upload your sketches this way.
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