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31  Using Arduino / LEDs and Multiplexing / Re: Problem wiring an Uno v3, MAX7219 and an 8x8 matrix. on: June 07, 2014, 01:18:52 am
Your video is private.

The most common error is the matrix plugged in the wrong way around/upside down. Have you tried reversing that?
32  Using Arduino / Programming Questions / Re: Is There a Way to Increment and Scroll through Declared Variables? on: June 05, 2014, 09:51:34 pm
Try this:
int MyArray0[] = {1,2,3}
int MyArray1[] = {4,5,6}
int MyArray2[] = {7,8,9}

const int * (MyArray[]) = {MyArray0, MyArray1, MyArray2};

void loop
  static int x;

  const int *CurrentArray = MyArray[x]; //This is the line it doesn't like
  if (CurrentArray[1] == 5) {Serial.print("looks like it's array #2 again!");}
  x = (++x) % (sizeof(MyArray)/sizeof(MyArray[0]));

Obviously const won't work if you intend to change the value in the arrays.
33  Using Arduino / LEDs and Multiplexing / Re: 8x8 LED matrix with the MAX7219 on: June 04, 2014, 10:26:46 pm
If you download a copy of the datasheet for the MAX219 you will find the circuit that everyone uses as part of that datasheet. How to size the resistor is also part of the information supplied. Google is your friend.
34  Using Arduino / Storage / Re: Ethernet shield SD card initialization failed on: June 03, 2014, 11:59:03 pm
What I have since found is that the SPI library will use the SS defined in the libraries even though you may be using a different SS for your device. For example, if the Ethernet is on SS pin N and the SD card uses pin M, and N is the same as the SS defined in the library, when you use the SD card (pin M) the library will also set N, in the library code. This is not what you expect or want to happen.

My way around this is that if I have one device then I will just use SS, if I have more than one device then I cannot use SS (ie it is lost to me as a valid pin) and I need to use two other pins and manage it myself. This assume that the pins are not hard wired, like on a shield.

An alternative is to hack the libraries to not use the SS pin the way it does.
35  Using Arduino / Programming Questions / Re: custom characters on: June 03, 2014, 07:01:29 am
For a string you should use LCD.print, not LCD.write. Before you use a custom character you need to define it in the LCD.

Also, are you sure that the LCD actually works? Do the example programs work?
36  Using Arduino / LEDs and Multiplexing / Re: Getting 3 LED loops to run "simultaneously" help please on: May 25, 2014, 08:52:53 pm
I have a sketch call Multiblink that allows you to set up this sort of stuff just by changing data tables in the code. See the code repository link below if you are interested.
37  Using Arduino / Programming Questions / Re: Program does not go into the switch statements at all ! on: May 22, 2014, 09:42:15 pm
A character is either going to be equal to comma or not. The first and second if statements take care of all possibilities (== and !=) if you just compare to comma, so the last else part never gets executed.

Are you sure you need the last else statement? Should this just be outside the if/else?
38  Using Arduino / Sensors / Re: Issues with recently purchased LM35D on: May 19, 2014, 07:58:27 pm
You should be posting code and circuit diagrams to help us. Circuit is especially import in this case, especially if you have long wires to the sensor.

The sensor is very sensitive to the voltage calibration. I have a library that uses the internal voltage reference to calibrate the sensor voltage. See the link to the repository below, in the signature block.
39  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: May 17, 2014, 04:17:08 pm
Font can easily be rotated. Use Font builder for that.

The shift functions can be changed. There is a table in the source code that maps the request for a shift to an actual shift. Hardware remapping selects a different shift depending on the configuration. Have a go at that if your feel like it. At the moment I don't have time to go back to these libraries to make major changes.
40  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: May 16, 2014, 11:27:17 pm
DIn on the right side is good because the module on the right is module 0.

I am not clear what hardware you have selected in the scrolling video. Is it the generic module?

In the hardware test video, your columns are scanning from left to right (ie, col 0 is on the left), so that needs to be reversed with REV_COLS=1. Your rows are scanning from top to bottom, so the rows do not need to be reversed (REV_ROWS=0). I really can't see why that would not work...

41  Using Arduino / General Electronics / Re: decreasing keypad pins on: May 16, 2014, 11:04:11 pm
Lots of keys (100 or more) using 3 pins

This is the probably same or similar as the 4017 mentioned above.
42  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: May 16, 2014, 03:18:16 pm
If understand you correctly the mapping you see , as-is
 D0 D1 D2 D3 D4 D5 D6 D7

This is probably configured as HW_DIG_ROWS=0, HW_REV_COLS=1, HW_REV_ROWS=0. This looks like generic hardware config.

The modules upside down
 D7 D6 D5 D4 D3 D2 D1 D0
This I think is HW_DIG_ROWS=0, HW_REV_COLS=0, HW_REV_ROWS=0.

Neither combination has been tested and probably won't work without some debugging.

Note: Late edit due to error in the explanation.
43  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: May 15, 2014, 06:32:39 am
Sure, and which LEDs are on when it says that? The point of the test program it to turn on the led and tell you which row/column you are looking at.
44  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: May 14, 2014, 09:43:10 pm
It is a test program in the MD_72xx examples.

There is a library that you do not have in the Parola test example. That is documented in the code file. You need to read these and not just load and compile.
45  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: May 14, 2014, 09:37:19 pm
What does the matrix testing demo show?
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