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Author Topic: MAX7219 + LED Matrix Wiring?  (Read 290 times)
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Well today i received my parts in the mail
2  8x8 dot matrix led display http://www.taydaelectronics.com/8x8-dot-matrix-led-display-red-3mm.html
and a Max7219

I found out in a hurry that the matrix does not fit in a breadboard. I'm not sure how to get around that at the moment.as i don't have any wire, just jumpers and I only have one half breadboard.

 Also the wiring diagram is a little confusing I know you need 1 resistor and a cap, but not sure how to wire them all the diagrams i have seen are pretty confusing. was wondering if anyone had a fritzing diagram of the set up with an Arduino that they could possibly share?
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use the datasheet of your display and connect each column  cathod pin to each "dig" pin of the MAX7219. (row 1 -> "dig 0", row 2 -> "dig 1"etc)
after that connect each row anode pin to each segment pin of the max7219 (row 1 -> seg a, row 2 -> seg 2" etc.
find the right current set resistor, connect the IC to your platform and it's done smiley

column   display pin    MAX7219 pin
1                   13                     2
2                   3                      11
3                   4                      6
4                  10                      7
5                    6                      3
6                   11                      10
7                   15                       5
8                   16                      8

row   display pin    MAX7219 pin
1                 9                14
2               14                16
3               8                  20
4              12                  23
5                1                  21
6               7                  15
7               2                  17
8               5                  22

pixel forward current is 20mA but you must think of the total power dissipation and a protective value if the scan duty cycle is too slow during programming tests. A 10mA is more conservative value for test. so Rset must be a 62K resistor. (after if all works fine and the duty cycle is set you can decrease the Rset value to increase the led current. the maximum allowed current is 500ma divided by number of pixels (8 units) and duty cycle. You can decrease the value to 15K I think).

Don't forgot to use a 100nF and at least 10uF caps near the power supply pins (19 and 9) of the maxim IC as a  local current tank.
connect the CLOCK, DIN and LOAD pins to your arduino platform. best if connected to the SPI bus (SPI UART is faster than bit twidling)
DOUT can be left unconnected if no daisy chain is used.

I've done a google search after that and i've foiund this:
http://www.gammon.com.au/forum/?id=11516

but be careful if you want to use an allready made library you must be sure of the right wiring order.
« Last Edit: April 14, 2014, 09:00:21 am by Genesis92 » Logged


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WOW that is super helpful thanks man!
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no problem smiley-wink
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