Converting a 16 LED (74HC595) circuit to MAX2719

Other Hardware General Electronics
1

I'm pretty new to electronics and have had a lot of fun experimenting with my Arduino and various chips.

Right now I have a breadboard setup with 2x 74HC595 chips and 16 LEDs like the example on http://arduino.cc/en/Tutorial/ShiftOut

It works great and I've had fun experimenting with shifting data to them.

I have a couple of MAX7219 and I'd like to use one to power these 16 LEDs. I understand I wouldn't need a resistor for each one any longer. I've read the datasheet for the MAX7219, and looked at various tutorials online, but they mainly seem to talk about how to use an 8x8 LED matrix.

Instead of a matrix, I want to drive individual LEDs.

Here's my thought:

Should I design the circuit so 8 of my LEDs would be row 0 (with 8 columns, obviously), and the next eight would be row 1? It feels weird hooking it up that way, but if the chip handles all the multiplexing then I guess it makes sense.

Or am I going about this all wrong?

Basically, I'm building myself up. I started with a single LED. I then moved on to a few controlled by different pins on the Arduino. Then I moved to a single 74HC595, then a double.

My ultimate goal is to have a mini-light show on a miniature set. I just want to learn it piece by piece as I go.

Sorry if this is too much of a newbie question. I've tried to explain myself, provide the schematic I have working for the 74HC595, and did my research (but failed) at finding much beyond matrices on the MAX7219.

Thanks

2

Hello and welcome,

Read this it may help you :wink: http://modelrail.otenko.com/arduino/controlling-lots-of-leds-with-your-arduino

3

Wow. Thank you guix for your quick & accurate response.

I can't tell you the countless sites I've been through from my google searches that only found matrices.

This kind of thing was exactly what I wanted (mine's like a county fair, so I can use the same ideas as for a train set.)

The distribution board does look pretty tedious, but probably well worth it.

Thank you

4

Tahii:
Should I design the circuit so 8 of my LEDs would be row 0 (with 8 columns, obviously), and the next eight would be row 1? It feels weird hooking it up that way, but if the chip handles all the multiplexing then I guess it makes sense.

Or am I going about this all wrong?

No, that's correct. Remember to tell the chip you only have two rows.

(nb. It might be two columns instead of two rows, I can never remember which way it does the multiplexing...)

5

You tell the chip 2 digits.
Each digit will have 8 LEDs - anodes between digits are connected in parallel (a,b,c,d,e,f,g,dp) to the Segment pins, and each digit will have a common cathode connected to a Digit pin, Digit0 and Digit1. Then you set the Scan limit register to 0x01 to tell it 2 digits.
Writing to Digit0 then controls 8 LEDs, and writing to Digit1 controls the other 8.

6

Can i use de max7219 with regular leds (Vf3.2, 20ma) on a matrix common anode common cathode ,4 rows 7 colums(7 leds each row )?

7

how can they be both common anode and common cathode??

anyways..

@OP..

here is a wiring diagram I did along time ago when I played with my first MAX chip..

I too wanted individual leds... and not a 'matrix'.. but in the end.. how you arrange/align the leds is up to you..
(as long as they are WIRED in a matrix array type set-up)

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as you can see.. (in this diagram) there are only 4 groups of 8 leds.. so I m only using 4 DIG (GND) pins on the MAX chip..

hope this helps..

keep in mind.. the MAX chips do NOT support any kind of PWM.. (although you do have 15 levels of brightness you can loop through if you like) :slight_smile: