I would like to build a large LED DOT Matrix display with multiple 8x8 Dot Matrix blocks.
Where there will around 10 rows and 3 columns.
I do not need a running display. The data will be static.
Please suggest a good library for the 8x8 LED dot Matrix with MAX7219.
An 8x8 display does not agree with your original statement of 10 rows of 3 columns or requires two of them.
Not sure what your project is or the type of display you are creating but for a simple display of 3 columns of 10 LEDs, I'd go with using WS2812 strips or even rings instead - depending on the display needs.
Not only do you get full RGB color control with intensity control but they are WAY easier to wire up.
You can get them in 30,60, or 144 LEDs per meter. and cut them to get the desired number of LEDs in the strip that you want/need.
They also come in rings of various sizes, from 8 to 60 leds and in strips of 8 on a small PCB.
For 8x8 LED matrix with MAX7219 there are couple of libraries out there:
- Marco's libraries: MD_MAX72XX combined with MD_Parola
This library offers lots of features for doing text & effects.
For simpler things there are several other libraries that are useful:
- Matrix
- MaxMatrix
- 72xxPanel
For the WS2812 you will want the AdaFruit_NeoPixel library.
It is very nice and easy to use.
--- bill
Alternatively, for a quick solution using LED matrix you could go with some of the ready to go solutions from Adafruit.
They have several products including a 16x8 i2c based product.
They have libraries for all their products.
But if all you want/need is 3 strips of leds, then I would encourage you to take a look at the WS2812b led strips.
They are fairly inexpensive on Ebay.
--- bill
bperrybap:
An 8x8 display does not agree with your original statement of 10 rows of 3 columns or requires two of them.
--- bill
I will use multiple of them, around 850 8x8 dot matrix blocks.
Joy:
I will use multiple of them, around 850 8x8 dot matrix blocks.
850 ??? Wow. Thats a lot. That is well beyond what you said earlier even using 10 rows of 3 individual 8x8 matrix displays. Like more than an order of magnitude (850 is WAY bigger than 30)
This is over 54 thousand individual LEDs potentially involving some very long daisy chains of 7219 chips.
You are looking at a whole new universe in terms of electrical connectivity not to mention power requirements, and probably need to be looking at some other solution.
When you chain/cascade MAX7219 chips together, the clock and data signals often start to degrade or pick up noise and start to corrupt the displays and after going through about 10 or 12 chips.
It is possible to do better but it takes careful short wiring, very clean power, and potentially fixing/correcting the poor design on some of the 7219 led matrix PCBs that are typically offered from places like Ebay.
You may want to google around a bit and read about the issues people are having when trying to use more than 8 to 10 max7219 chips in a daisychain.
I'm not saying it is impossible, but it will likely be very difficult to do and you for sure will not be able to drive all 850 display panels using a single set of data, clock and cs signals.
You will likely have to break them up into groups of about 20 in a chain which then require a lot of pins just to drive the SPI /CS pins.
For that many LEDs I'd be off looking at some much larger matrix panels from somebody like SureDisplay.
--- bill
Hi, excellent, sometimes you get the answer before you even ask.
I bought a 488 display out of curiosity, and will soon try it out. To know in advance for what library to look for really helps. Thank you.
ZinggJM:
Hi, excellent, sometimes you get the answer before you even ask.
I bought a 488 display out of curiosity, and will soon try it out. To know in advance for what library to look for really helps. Thank you.
The library used will depend on the chipset used.
Many of the larger display matrix modules have built in chips and use other chips than the 7219.
The ht1632 is quite popular and some use 595 shift registers which are a pain and require lots of CPU bandwidth.
--- bill