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1  Using Arduino / General Electronics / Re: Difference between two 74hc595's on: April 27, 2014, 01:19:36 am
Yes! I think that must have been it.  I could have sworn I tried that through all my messing around but I guess not.  Anyway, seems to be working now.  Thanks!
2  Using Arduino / General Electronics / Difference between two 74hc595's on: April 26, 2014, 10:38:31 pm
I have a Texas Instruments SN74HC595N 8 bit shift register and a NXP 74HC595N 8 bit shift register.  I am able to do the basic LED lighting using the TI shift register but when I swap it with the NXP, it does nothing.  Here are the two datasheets I found:

TI
https://www.sparkfun.com/datasheets/IC/SN74HC595.pdf

NXP
http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf

I'm not terribly tech savvy at the details of these but they seem to be the same to me.  Is there something I'm missing?  I have multiple of each register from each company so I feel I've ruled out the problem of having bad parts.  Any advice would be much appreciated.
Thanks!
3  Community / Bar Sport / Re: Registry Cleaners on: July 22, 2011, 10:12:14 pm
linux is nice and all but if you need to install anything that you can't do with sudo apt-get install, its just a pain.  I've spent countless hours trying to get something to work on linux that takes two seconds with Windows.  However I intend to keep trying until I get it right. smiley
4  Community / Bar Sport / Registry Cleaners on: July 22, 2011, 02:39:46 pm
Does anybody have a good, free registry cleaner that they trust?  I feel it would be a good idea since I've installed and removed a lot of programs in the few years i've had my computer and I'm worried if I just pick a random one I'll get screwed.
Thanks.
5  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 12, 2011, 07:14:54 pm
That makes sense.

All is good now.  The code,
   digitalWrite(latchPin, LOW);
   shiftOut( dataPin, clockPin, LSBFIRST, 1 );
   digitalWrite(latchPin, HIGH);
was in a switch statement in the void loop() function.  So, like MarkT said, the 74hc595 output pin was constantly going low and high causing insufficient voltage.  So I put the switch statement in an if statement that is triggered when a button is pressed.  It now successfully turns on the relay when the button is pressed and ignores that code until another button is pressed so it doesn't keep cycling through it.

If anyone is curious the relay is a Zettler AZ822-2C-5DSE I got from Allied.  I rigged it up with a 2n3904 transistor, a 1n4002 diode across the relay coil to +5v, a 1k resistor from the shift register output pin to the collector of the 2n3904 and grounded the base.  The collector draws 3.5 mA and the coil draws 27.8 mA. 
Thanks for everyone's help!
6  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 12, 2011, 04:17:35 pm
5 Volts! However then I have to time subsequent button presses carefully.  I lowered the delay to 150.  Any lower than that and the voltage starts dropping.  It's getting better though.  Thanks MarkT.
7  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 11, 2011, 10:44:37 pm
Also, I don't know if this matters or not, but this is the second shift register my Arduino is running.  The other one is powering an LCD using the ShiftLCD.h library.  It uses pins 2,3 and 4 while the one I'm having problems with is using pins 8,9 and 10. 
8  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 11, 2011, 10:24:44 pm
No frequency function.  Could it be a programming error?  This is the code pertaining to the shift register. 

const int latchPin = 8;   // Pin connected to latch pin 12 (ST_CP) of 74HC595
const int clockPin = 9;   // Pin connected to clock pin 11(SH_CP) of 74HC595
const int dataPin = 10;   // Pin connected to Data in 14(DS) of 74HC595

void setup(){
  pinMode(latchPin, OUTPUT);
  pinMode(dataPin, OUTPUT); 
  pinMode(clockPin, OUTPUT);
}
void loop(){
   digitalWrite(latchPin, LOW);
   shiftOut( dataPin, clockPin, LSBFIRST, 1 );
   digitalWrite(latchPin, HIGH);
}

Thanks a lot for the help so far guys.  I go around to a lot of forums during my boring day at work and this is by far one of the most helpful and knowledgeable ones.
9  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 11, 2011, 10:07:58 pm
I just tried two brand new, right out of the package 74hc595's and they did the same thing.  Only 2.24 volts at the output pin across a 1k resistor and an LED to ground.
10  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 11, 2011, 09:56:20 pm
I used an 1n4002 across the relay coil
11  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 11, 2011, 09:36:05 pm
Well now I just put a 1k resistor and an LED in place of the relay coil and I got 2.24 volts between the output pin of the 74hc595 and ground and 1.3 mA between the resistor and the LED.  Shouldn't I be getting 5v out of the shift register?
12  Using Arduino / General Electronics / Re: 74HC595 output voltage on: July 11, 2011, 08:55:20 pm
Yeah, the relays take around 30 mA.  I was planning on using the transistor/diode setup to drive the relays anyway but I was just doing it this way to test them and because I was kind of lazy.  I'm still curious why I'm only getting less than 2 volts from the output pin of the shift register though.
13  Using Arduino / General Electronics / 74HC595 output voltage on: July 11, 2011, 08:03:35 pm
I am using an Arduino Uno and a 74hc595 shift register which I need to power eight relays.  The relays coil needs 5 volts and is about 170 ohms.  So I rigged up the 74hc595 and one relay on a bread board to test it.  The relay is drawing 5.3 milli-amps and not turning on.  I found that it is only being supplied with 1.83 volts.  I have confirmed that pin 10 and 16 of the 74hc595, the voltage supply, do have 5v.  Does anybody know what could cause this?
Thanks as usual!
14  Using Arduino / Programming Questions / Re: using shiftLCD library on: July 10, 2011, 08:42:35 pm
Good call, I wired them wrong.  Dummy points for me.  I'm still curious about the difference in R/W pins though.  It seems right there you could save a pin on the Arduino using the LCD if you just wire it to ground.  Maybe that won't work without the shift register though. 
Thanks johnwasser.
15  Using Arduino / Programming Questions / using shiftLCD library on: July 10, 2011, 07:16:55 pm
I am using a 74hc595 shift register with an Arudino Uno so I can save pins using the 20x4 LCD.  So I downloaded the shiftLCD library that I found here:
http://cjparish.blogspot.com/2010/01/controlling-lcd-display-with-shift.html
I noticed on that site, it tells you to ground the R/W pin of the LCD.  But on this page:
http://www.hacktronics.com/tutorials/arduino-character-lcd-tutorial.html
It says the R/W pin goes to pin 11 on the Arduino. 
Which one is right?

The reason I ask is because I am displaying a menu on the LCD with two buttons that control whether the cursor goes up or down.  Whenever I put my fingers near the buttons, the cursor starts moving on its own.  I figure this is because I am grounded and therefore grounding the switch.  However when I used the exact same code without using a shift register and using LiquidCrystal.h everything went how it was supposed to.

Any suggestions?

Thanks a lot!
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