Count up timer on 7-segment display

Projects General Guidance
1

I am in desperate need of some help!

I'm currently trying to design a project that involves an arduino (duh!) and 2 Double row 4-digit 7-segment LED display. (see URL)

Double Row 4 digit 7-Segment Display

I would like to be able to do the following...

-first display = show a number of days that counts up
-second display = show a number of days that counts up
-third display = shows a number of days that counts up
-fourth display = show a number of days that counts down

I need the number of days to be set to a certain value.. i.e the first starts at 100 and counts up, the second starts at 200 and counts up, the third starts at 300 and counts up and the fourth starts at 365... but counts down

The count down display then must reset at 0 back to 365, after 4 resets, 366, then reset back to 365 (leap year compensation)

I need the updated values to write them selves to the arduino in case I lose power to the board. So that when I plug it back in the count starts from where it left off.

so to recap...

-4 4digit 7 segment displays running off 2 MAX7219 LED drivers
-3 count up every 24hrs, 1 counts down every 24hrs
-need to have starting values inputed, that get updated in the sketch as they change to prevent loss of count

I hope that this is well detailed enough, if there's any other information i can provide please let me know

thanks so much for taking the time to read my post!

2

So start writing some code. Get the functionality you want working to display on the IDE serial monitor to start, add SPI code to send it to the 8 registers in the MAX7219 will be trivial:

digitalWrite (ssPin, LOW); // ex D10
SPI.transfer(registerAddress); // 1 to 8 for digit display, others 0x09 to 0x0F used once in setup()
SPI.transfer(digitData);
digitalWrite (ssPin, HIGH);

Make that a function if you want, MAX7219 works fine at default settings for SPI.begin()

3

I will start there and see how far I can get, thanks CrossRoads!