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1  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 14, 2014, 02:17:14 pm
All the pin numbers are defined in the Parola_Test example. You can change it to whatever you want if they don't suit.
Code:
// User interface pin and switch definitions
#define  SPEED_IN      A5 // control the speed with an external pot
#define  PAUSE_SET   4 // toggle pause time
#define  JUSTIFY_SET  6 // change the justification
#define  INTENSITY_SET 7 // change the intensity of the display
#define  EFFECT_SET    8 // change the effect
#define  INVERSE_SET   9 // set/reset the display to inverse

There is not much to explain about the circuit. Look at other examples on how to connect a pot and a switch to the Arduino. There is a lot already on this forum for these basic Arduino connections, so it is not really worth explaining it again here.
2  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 14, 2014, 06:42:03 am
I am not sure I understand your question. Do you mean the control you see in the video? It is just plain switches and a pot, like are used in most of the simple arduino examples.
3  Using Arduino / LEDs and Multiplexing / Re: Problem with 8x8 Matrix and Parola, nothing displaying... on: April 13, 2014, 02:04:38 pm
I don't think that you can just change the LED modules and expect it to work. The matrix itself is wired differently and the circuit from the MAX7219 chip has to take that into account. The software will then accommodate the different row/column orientation that may result.
4  Using Arduino / LEDs and Multiplexing / Re: Problem with 8x8 Matrix and Parola, nothing displaying... on: April 11, 2014, 06:51:18 pm
Generally common anode or common cathode doesn't make a difference to the libraries except that the module orientation will change. The new version of the libraries includes changes to make the adaptation for novel arrangements much easier.
5  Using Arduino / Sensors / Re: Problem with Color sensor module TCS3200 on: April 11, 2014, 06:21:50 pm
I have a library for the TCS230 which I think works in a similar way to the sensor you have. The library has some example code that allows it to 'recognize' colors which could be interesting for you. See the code repository link below to access the library if you are interested. If you do download, look for the PDF file that explains how to calibrate the sensor.
6  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 11, 2014, 06:14:55 pm
Quote
Can i expand this matrix vertically

You need to explain what you want to do. You can stack the displays on top of each other - that is just a physical layout.

If you want your software to operate as if it was a big screen, then you will need to handle the operations between the 'lines' of display. The ability to define zones has made this much easier - just define a zone for each line.
7  Using Arduino / Programming Questions / Re: Why == works in an if statement? on: April 06, 2014, 10:16:19 pm
Quote
Anyone know if > or <  are valid comparison operators or is >> and << used instead?

< and > are the correct comparison operators as are >=, <=, and != (not equal to).

<< and >> are used as bit shifting operators. (1 << 3) is the digit 1 shifted to the right 3 binary positions (ie, 00000001 becomes 00001000), or 2^3 = 8 decimal.

The questions you are asking are answered very clearly if you look up a C++ reference for 'operators'.
8  Using Arduino / LEDs and Multiplexing / Re: MAX7219 breakout board for 64 discrete LEDs on: April 05, 2014, 07:27:42 pm
What applications is this for?
9  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 05, 2014, 02:46:34 pm
That's good news that it works for you as well.

The source code download will always be the latest working copy as I develop a new release, before the official release. The zip file releases include updated documentation. This applies for Parola as well. You can look at the history of the source code to see my check-in comments as to what has changed.
10  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 05, 2014, 03:26:05 am
Have you taken the latest from the source code section?

Memset was definitely wrong ...
11  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 05, 2014, 12:37:42 am
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After this fix, no more funky pixel stuff
I am staggered that the library worked at all reliably given that this clear function is called for EVERY comms cycle. Well done finding that! Thanks. Having fixed the problems with memset, DECODE does not seem to be needed any more.

Quote
This would reduce the number of commands sent from NxN to just N
Yes it would. The library is like that for historical reasons and it is time to address this inefficiency. Commands are rare compared to the number of other messages, so it was left alone at the time when there was a lot of other stuff to sort out and never came back to it. I have fixed this now.

Quote
Any reason not to use the SPI library that comes with the IDE
Nothing specific (I assume you are referring to the SPI.h library). I originally used the library but decided it would be neater (header files, better control) if the specific code was just included in my lib. The defines for SS, MOSI, SCK are from the Arduino header files.

Repo has been updated with revised library code.
12  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 04, 2014, 03:39:21 am
My findings, running the eyes demo (which has always had the most 'artefacts' with my setup) and 22 Parola modules:
  • With no changes artefacts happened every time I cold booted and then get worse with warm boot. Multiple displays affected every time
  • Putting the NODECODE in the initialisation immediately cleaned it up and the artefacts. Cold boot, warm boot made no difference, they just don't appear.
  • Changing the order for the SS pin high made no difference without the DECODE.

Looking up the didtalWrite() manual reference:
Quote
If you do not set the pinMode() to OUTPUT, and connect an LED to a pin, when calling digitalWrite(HIGH), the LED may appear dim. Without explicitly setting pinMode(), digitalWrite() will have enabled the internal pull-up resistor, which acts like a large current-limiting resistor.

So I am guessing that this code
Code:
digitalWrite(SS, HIGH);
pinMode(SS, OUTPUT);
is not doing anything but setting the input resistor rather than setting the pin HIGH.
Update: I also found this, which answers my question
Quote
a pin that is configured to have pullup resistors turned on when the pin is an INPUT, will have the pin configured as HIGH if the pin is then switched to an OUTPUT with pinMode().

If only there was a way to 'reset' the 7219 chips without cycling power, I think we would have no problem...
13  Using Arduino / Sensors / Re: New library for TCS230 RGB Color Sensor on: April 03, 2014, 05:23:12 am
You need to turn Vcc off. The problem will be that it turns the sensor off as well, so the chip will need to be reinitialised when power is applied. You may be able to modify the sensor so the LEDs are being powered separately from the chip.

I understand your comment on pin 5, but that is only true for the Uno and related Arduino. As per my previous post, the pin will change depending on the type of Arduino being used.
14  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 02, 2014, 03:36:51 pm
Thanks all for your testing. It's a bit like having a virtual R&D group smiley
15  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: April 02, 2014, 02:54:54 am
MD_MAX72XX repo has been updated with new begin() code to initialise OP_DECODEMODE. Let me know how you all go.
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