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1  Using Arduino / Storage / Re: how to read sd file line by line on: August 25, 2014, 04:07:13 am
I would do your second option. The sd library will buffer for you as you read through the file.
2  Using Arduino / Sensors / Re: Need Help with colour sensor module coding (TCS3200) on: August 23, 2014, 06:48:30 pm
My code repository has a library for this device. Of interest for you might be the documentation with the library on how to use and calibrate the device.  Link below in the signature block.

What you want to do is in your software, not inherent in the way the sensor works. The sensor will return the rgb value of the color it sees. If all you want are the r and b vales, just use those. Your software will need to decide how you handle colors like purple that present a red and blue reading, for example.
3  Using Arduino / LEDs and Multiplexing / Re: MAX7219 Random Scrolling digits on: August 21, 2014, 03:08:10 pm
My MD_MAX72xx library supports transformations primitives for single pixel movements natively. The library is in the code repository linked below if you are interested.
4  Using Arduino / Displays / Re: Arduino Uno w 16x2 LCD Displaying Jumbled letters. on: August 21, 2014, 07:20:34 am
Switching a solenoid creates a current spike to overcome the inertia of the mechanical system. This will probably momentarily exceed the Arduino pin spec and cause a brownout type situation for the MCU and/or the LCD display. Having more relays will increase the effect. It also seems you door latch is always on, which puts a constant load to which you then add the other solenoids.
5  Using Arduino / Displays / Re: Arduino Uno w 16x2 LCD Displaying Jumbled letters. on: August 21, 2014, 07:03:53 am
You cannot drive a relay solenoid directly from the arduino pins because they take too much current. You need to use a transistor to switch the higher current.
6  Using Arduino / General Electronics / Re: Switch de-bounce circuit. on: August 15, 2014, 07:05:58 am
I found this reference a good explanation when I was trying to understand the issues involved.

http://www.eng.utah.edu/~cs5780/debouncing.pdf
7  Using Arduino / LEDs and Multiplexing / Re: MAX7219 without scrolling on: August 15, 2014, 01:55:09 am
Look at the MD_M7xx library in the links below.  The library has examples of how to display letters and numbers. You don' have to scroll at all.

You will need to answer yourself questions as to whether the text digits will be centered or right justified, leading zero, etc. this will affect how you place the text in the matrix.
8  Using Arduino / LEDs and Multiplexing / Re: Multi-tasking LED's on: August 13, 2014, 05:23:38 pm
A sketch called Multiblink in my code repository (link below in the signature) may be useful for you. It can do what you need with minimal change.
9  Using Arduino / Sensors / Re: Arduino with 400 button ?? on: August 13, 2014, 03:14:37 am
This implementation using 3 digital control lines and a 4017 may be of interest: http://forum.arduino.cc/index.php?topic=235438

By adding in another 4017 you can get 1000 switches.
10  Using Arduino / Programming Questions / Re: switch statment changes for no reason? on: August 11, 2014, 05:51:51 pm
Buttonstate does not seem to be set to anything if there is no button pressed.
11  Using Arduino / LEDs and Multiplexing / Re: RGB LED easy smooth colour transitions on: August 07, 2014, 04:38:03 pm
The only suggestion I have is to experiment with the led thresholds. These determine the lowest level at which the led will be set by the software.
12  Using Arduino / General Electronics / Re: MAX7219 SPI Chain Length on: August 06, 2014, 05:26:54 pm
Quote
In terms of just the SPI communication, does the Parola code do anything special that the Arduino SPI library doesn't?

The control of the hardware is in the MD_MAX72xx library. No special things are done except the initialization is by the book according to the spec sheets, as mentioned by CrossRoads. You could download the library and see if it works better for you.

With lots of modules you should be using external power. The Arduino power supply won't be enough. Also make sure that the capacitors are as per the sample design on the spec sheet as that does make a difference.

What does you circuit for one module look like? Are you using standard module so your own circuits?
13  Using Arduino / General Electronics / Re: MAX7219 SPI Chain Length on: August 06, 2014, 09:29:26 am
I have had up to 20 connected together as part of testing my Parola project and others have many more than that, so the 10-12 limitation is probably not coming from the chips but somewhere else in your circuits.  The links for Parola and the forum are in my footer below.
14  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: July 30, 2014, 08:10:01 pm
Sorry, I was not clear. I meant use DATA and CLK pins different from the hardware pins, to avoid any contention issues. With the two different data streams, if the displays still don't work with just software SPI, then you are looking at a fundamentally different problem to chase down.
15  Community / Exhibition / Gallery / Re: Scrolling LED matrix display - Parola for Arduino on: July 30, 2014, 05:08:30 am
@oscomputing

I have sent you a new version of the library to try. There were a couple of bugs in V2 that have been corrected and this is pre release.
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