Hi, I have a problem with 10 pieces MAX7219. I have the necessary libraries and code downloaded from the website GitHub - MajicDesigns/MD_Parola: Library for modular scrolling LED matrix text displays. I use to Arduino UNO and my problem is: when connected 8 pieces displays everything works, but if I connect the remaining 2 pieces display the entire code spreads and takes what he wants, even when you edit the code on 10 screens. Does anyone know what to do?
Make sure you are using an external power supply. You will not be able to power 10 units from the USB supply.
Why marco_c your video on youtube at the beginning you have 12 piece display connected to the Arduino sensor shield, and you need to external power? I got it through the Arduino connected to a PC and there is the same as the input voltage mint you.
Each MAX7219 will have up 8 LEDs on at any one time. If each LED is getting 20mA, that is 160mA per MAX7219. With 10 of them, 1.6A may be needed. PCs limit USB current to 500mA, as does the PTC resettable fuse on an Uno or Mega.
You may have less LEDs turned on per MAX7219, the Intensity register might be at a lower setting, or the Iset resistor may be limiting the maximum current to a lower value. But eventually the combination of those could lead to a higher current external supply being needed.
and you need to external power?
My USB hub has external power (5V 1A) and the Parola modules have a much higher MAX7219 resistance than the modules you buy, so they use a lot less power.
Pretty much as CrossRoads explained, but you can also read this: MAX7219 and LED matrix power requirements – Arduino++
And you advise me where such a perfect source for my problem or at least buy scheme as such a source should look like? On the Internet I can not find it anywhere.
Firstly, have you worked out how much power you will need (at 5V, how many Amps do you need) for what you want to do? Then the rating of the power supply,in Watts, is the multiplication of Volts*Amps (eg, 5V and 2A is 10W).
The look for a power supply wit hthe correct rating. This can be a USB hub or a separate power supply module. It all depends on what your project is about and your experience with connecting wires, circuits, etc, so there is no 'perfect source' that anyone can suggest.
If you just want to have something to experiment with (ie, plus and unplug, change around, etc), then a 3A wall wart power supply (like this http://www.ebay.com.au/itm/AC-100V-240V-Adapter-DC-5V-2-5A-AU-Approval-Power-Supply-2-5A-5-5mm-x-2-5mm-/121993973208?hash=item1c67684dd8:g:pXwAAOSw1h5XQS~h suitable for your country) will be good for a while.
Hi folks,
Suppose we subdivide a long chain of LED matrices (36, to put a number on it) into 3 sections, each consisting of 12 matrices.
Can I (and is it wise to) power each section with a separate, voltage-regulated power circuit (9V battery + 5V/2A linear voltage regulator, with the ground of each regulator tied together)?
As long as all the grounds (including the Arduino ground) are tied together that should work.
