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1  Using Arduino / LEDs and Multiplexing / Re: 4" common anode 7-segments: driver reference to buy in 2014 on: September 20, 2014, 06:33:21 pm
I think Spanish translates to welding also.
2  Using Arduino / LEDs and Multiplexing / Re: 4" common anode 7-segments: driver reference to buy in 2014 on: September 20, 2014, 05:26:01 pm
Don't be confused by the name 'clock'. The '595 has an input shift register, and an output register.
The "shift register clock" (*SRCLK) the 8 clock edges that occur with the data to put 8 bits into the input shift register. 8 rising edges capture the serial data coming in.

The "register clock" (RCLK) that moves the 8 bits in parallel to the output register so they can drive the output pins. 1 rising edge moves the data into the output register. Usually the SS signal is used for this.

So an SPI transfer needs:

    digitalWrite (slaveSelectPin, LOW);                     << RCLK line goes low
    SPI.transfer (fontArray[fontArray[bitToSet]]);  << SRCLK goes  high-low 8 times to output 8 bits of data
    digitalWrite (slaveSelectPin, HIGH); // data outputs change on this rising edge  << RCLK line goes high to move data into output register
3  Using Arduino / General Electronics / Re: MOSFET-- what happens if voltage is reversed? on: September 20, 2014, 12:05:16 am
Which MOSFET? Most have an inherent diode that will conduct in the opposite direcetion if the voltage is reversed.
4  Using Arduino / LEDs and Multiplexing / Re: LED drivers on: September 19, 2014, 11:48:45 pm
Monocolor or RGB?
2x8x4 = 64 LEDs - just right for a MAX7219. 2 digits on each face.
I offer a little breakout board that makes it easy to wire up 64 LEDs:
http://www.crossroadsfencing.com/BobuinoRev17
5  Development / Suggestions for the Arduino Project / Re: Arduino mega, using pins that are not mapped. on: September 19, 2014, 11:34:24 pm
Try this one. Read the .rtf and the file itself to see the pin mapping,
6  Using Arduino / LEDs and Multiplexing / Re: 4" common anode 7-segments: driver reference to buy in 2014 on: September 19, 2014, 10:55:01 pm
D10 on '328P  must be set to OUTPUT on the SPI master, whether it is used as the latch pin (SRCK) or not (i.e., the pin can be doing some other output function).
If set as an Input and some other external device takes it low, the master will become the slave and go into SPI input function.
7  Using Arduino / LEDs and Multiplexing / Re: (help) single Array Leds on: September 18, 2014, 11:56:16 pm
Code:
byte pinArray[] = {3, 5, 6, 9, 10, 11};
byte brightnessArray[]= {0,50,100,150, 200,255;};
byte x;

void setup(){
for (x=0; x<6; x=x+1){
pinMode (pinsArray[x], OUTPUT);
analogWrite (pinsArray[x], 0); // outputs off to start, assuming High out = LED on.
}
void loop(){
// time to update the brightnesses? Or however you determine that.
for (x=0; x<6; x=x+1){
analogWrite (pinArray[x], brightnessArray[x]);
}
// adjust brightnessArray for next time change
...
}
8  Using Arduino / Microcontrollers / Re: What is the best method to making a custom PCB Arduino uno shield? on: September 18, 2014, 11:17:41 pm
I'd go with working with an engineer to make a 2-sided PCB ,then you can pawn off the design onto your friends too.
9  Using Arduino / LEDs and Multiplexing / Re: (help) single Array Leds on: September 18, 2014, 11:14:37 pm
You have a 2nd array that holds the analogWrite value you are sending to the pins in the first array?
10  Using Arduino / General Electronics / Re: Need Suggestions for Extending Approximately 40 Wires within 1 larger Wire on: September 18, 2014, 11:12:07 pm
Use 5 lengths of CAT 5 wire with 4 pairs of twisted pair wire in each. Pull the bundles out of the outer insulator and rebundle into one.
Go browse Home Depot and Staples.
11  Using Arduino / Displays / Re: Large LED sign on: September 17, 2014, 09:52:25 pm
There are lots of Time Libraries.
Translating to the 64x32 display is dependent on the hardware that drives the display.
Does it use a large array with 1 bit/LED? Something else?
12  Community / Bar Sport / Re: Who hasn't accidentally touched a mains voltage once or twice? on: September 15, 2014, 06:39:09 pm
I've only casually brushed a live wire a couple of times with a dry finger, got just enough tingle to realize "Damn! that was close!" , never had a big jerk away wildly out of control reaction.
13  Using Arduino / Displays / Re: Large LED sign on: September 15, 2014, 06:35:59 pm
Yes, 5VDC supply with a higher current rating is fine.
The parts will only draw what they need.
I don't see a needed current rating, so I'd estimate needed amount like this:
64/8 x 32/8 = 8x4 8x8 matrices, or 32 matrices.
Assume each matrix will have one column of 8 LEDs on at one time, drawing 20mA each x 8 =  160mA total.
32 * 0.16 = 5.12A, so you'll need a pretty hefty supply.
14  Using Arduino / Project Guidance / Re: portable ledstrip project on: September 15, 2014, 06:27:45 pm
These work well
http://www.pololu.com/category/132/step-up-voltage-regulators
I used one of the 12V models to drive 10 strings of 5 LEDs (need to count them now, has been a while) in this box: (lower left block & lower right block of 4x5)
and to send 12V down two sets of 42+ meters 4-conductor 26 AG wire (+12V, Gnd, Tx, 4th not used) to 2 boxes similar to this (with simpler control card, a promini actually, in the middle) for their lights.


15  Products / The Arduino Starter Kit / Re: Project 2: purpose of 10k resistor? on: September 15, 2014, 08:41:49 am
I've personally [edit:] Never used an external resistor with a push button/switch.
I use the internal pullup, and wire the switch to connect to Gnd when pressed.
Then I just look for a LOW to see if it's pressed.  A simple matter to think of active as LOW vs HIGH:
Code:
void loop(){
if (digitalRead(pinX) == LOW){ // button pressed?
digitalWrite (ledPin, LOW); // assumes LED is wire with Anode to +5, pin pulls cathode low to turn it on (with series current limit resistor)
}
else {
digitalWrite (ledPin, HIGH); // drive cathode high to turn LED off
}

}
Or with LED wired the other way around, pinX to Anode, cathode to resistor to Gnd:
Code:
void loop(){
if (digitalRead(pinX) == LOW){ // button pressed?
digitalWrite (ledPin, HIGH); // drive anode HIGH to turn LED on}
else {
digitalWrite (ledPin, LOW); // drive anode LOW to turn LED off
}

}
Positive logic, negative logic, active high, active low, call it whatever you want, just realize it's a simple thing to write the code to act one way or the other.
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