Vertical scrolling text for LED matrix display

[RGV250]

Hi,
I have a large LED matrix display and plan to use it as a clock. I thought it would be a nice effect to have the numbers scroll down as they are updated and wondered if anyone has done it to save reinventing the wheel or if anyone has any ideas.
My thought is that I will need to have an array for each position to hold the rows for the current number and the next one. When the number needs to change shift the rows down quickly.

Regards,
Bob

[joesaliba]

Hi Bob,

I would love to convert this code from Arduino as there are a lot of possibilities using the MAX72xx and LED matrix. But there is a lot in the code which I am not understanding, mostly the data table.

Regards

Joe

[RGV250]

Hi Joe,
The effects look good but I think it will be a nightmare to understand, I could not even find where to actually download the code from which does not fare well.
The other thing is my display is controlled with a multitude of 74HC245 octal transcievers, 74HC138 3 to 8 line decoders and 74HC595 shift registers along with APM4953 drivers.
It has taken me a while with a multimeter figuring it out, it is getting to the point of why am I bothering but it is the challenge that keeps me going with it, I am sure we have all been there.

Bob

[top204]

The trick with scrolling and moving images and text on LED matrix units is that the images are stored in RAM and transmitted to all the units as if they are a small graphic LCD. Remember, the font characters are just images held in flash memory just like a graphic LCD's font.

Then it is a straightforward task to manipulate the RAM and transmit the block of RAM to the display all in one go, because the RAM usage is very small. I did a few tests with the MAX7219 devices about 15 years ago and got them working as a matrix, but ran out of time, and motivation, to carry on with them. :-) I did the same with the WS2812B matrix I made and showed the video on thr facebook site a few years ago, and the game of life project I did in about 2011 for the Amicus18 board and an LED matrix board that was available then.

I looked at that MX7219 library a while back and also had difficulty finding the code, but I think I did, and the code, like a lot of C++ code, is horrendously bloated and full of stuff that is not actually needed, thus making it difficult to read and understand. I like to call it "Ego Coding" :-)

[joesaliba]

If someone is missing the Arduino code I can upload it here.

I also managed, to a certain extent, the MAX7219, but lacking the ability to scroll.

Also I bought some cheap MAX7219 with dot matrix LED installed and the table I used made the text orientation incorrectly displayed.

Further reading on the internet, I learned that there are some LED matrix LED that differ from others, and this is the problem. What there is in that library is that by a simple selection, i.e.: - Display = 1 or Display = 2, the orientation problem is solved without additional tables. In other words, the data table is `rotated' according to the display used.

Regards

Joe