Some Question about a Score-Counter


my first post.
i’m quite new to arduino, going to order a kit in the next few days.

i’m addicted to table soccer, like the garlando deluxe

i already “modded” it to have some LED lights from IKEA.
however, i wanted to go a little bit more crazy :wink:

i’m planing to make a little intel atom server inside the table, that has a PHP/MySQL Server, controlled with a Mimo USB Touchscreen, and using some Arduino technology for some fancy LED stuff.

after each goal, the player presses some buttons near the handle, telling the system which figur shot the goal. this gets registred in a database along with several other datas, like player name, time since last goal, etc. at the end, i can make statistics about who scored best, shot most with with figur, etc.
so far, this is all done with flash and the Server for logging.

now, where does arduino comes in?
well, for displaying the Score with two 7-Segment displays, and maybe two LED bars with each 6 LEDs (official rules for garlando only counts to 6 goals, not to ten).

as i’ve read, there is a library for “talking” to 7 Segment displays using the Max 7221/7219.
thats seems quite good, and i think i could programm it that way.

however, is it possible to launch a Arduino Programm at system start up without any interaction?
as said, when i power that computer, the flash front-end is set to autostart, as is the server. but i also need the arduino application to start at systemboot.
i’ll be using Mac OS X or Windows (tried linux, but its too uncomfty for me)

further, i didnt found a shop in switzerland where i could buy eighter MAX7221 or MAX7219.
is it safe to buy that chip from ebay?
and what exactly are the differences between those two at all?

thanks much :slight_smile:

the arduino code you write is on the atmega chip and starts as soon as you power the board. So if your board is always plugged into the motherboard via usb cable, as soon as you boot your computer the program starts running.

The MAX7219 and MAX7221 have different current designs. One expects you to “source” the current (output pins connect to light anodes, providing current to flow through them) and one expects you to “sink” the current (output pins connect to light cathodes, drawing in current that flowed through them). You should google for “MAX7219 datasheet” (or any other package name) and find the PDF that describes the part.

If you find an eBay vendor with hundreds or thousands of sales, you can roughly trust their eBay reputation. Primary vendors are Digikey or Mouser or the like.


One expects you to “source” the current . . . one expects you to “sink” the current

I wish that were true! In fact, both require a common cathode circut. The differences between the two are relatively minor. I use the two interchangeably.
(The 7219 is cheaper, but if you order free samples from MAXIM get the 7221.)

The differences mentioned here . . .
(slightly different SPI & EMI) are true, however both the LedControl and Matrix libs support either.

The main difference for me is that in order to support reduced EMI, in shutdown, the MAX7221 digit drivers go high impedance, rather than V+ as in the MAX7219. However, even that does not change how they are wired up or used.

In short they are pretty much the same. (Just FYI)