question about the MAX7219 IC

i am new on arduino and want to control the led matrix, but i cannot control the IC from my arduino. i wired the connection and the matrix is light up. yet when i put the program to arduino it no difference no matter i do what for it. and the led matrix is light up but sometimes will off. it is the question of the wire? and the last question. i don't know how to calculate the resistor on the Iseg. i am using 8 AA battery 12v for the IC power supply. which resistor should i use. the previous problem will occur when i use the wrong resistor? i know the problem may be a easy question but i cannot solve. thank you every one spend time to read this

. i wired the connection and the matrix is light up.

That means you have wired it up wrong. What circuit are you using?

what mean of wt circuit? i am ask someone the matrix is light up can be normal if the power supply to the IC

I think Mike is asking how you have the various pieces connected or wired up.

Could you draw a diagram of which pins are connected to which components, for example? Perhaps a picture of the project?

Post your code too, maybe it’s the registers that are wrongly set (I’m thinking about the test register).

http://www.flickr.com/photos/basarakit/2852982172/
i use the code from arduino playground and try to follow it a to seg dg and h to g for the segment part. i also change the pin to my pin number.

the playground link
http://www.arduino.cc/playground/LEDMatrix/Max7219

thank you

Hi again,

Looking at the website of the chip's manufacturer, I see that the max supply voltage is 5.5V with an absolute max rating of 6V, while I understand from your initial post that you are supplying it with 12V. Perhaps that explains why the circuit is not functioning as desired?

The chip may be dead as a dodo. Your arduino may not be too happy if it's getting 12V on any pins except the one for raw power to the voltage regulator.

As for selecting the resistor Rset between the power supply and the Iset pin, the same page seems to recommend a typical value of 9.53K for a current limit of 40mA sourced from your segments drivers, while the datasheet seems to recommend the same value as a minimum, and states that the current limit is 100 times the current flowing into the Iset pin.

I would assume that a resistor twice the value would create a current half the intensity and recommend to respect the minimum value for Rset. As for calculating Rset for a supply voltage of 12 volts, if that was part of your question, I would contend that the question is moot since at 12 V the IC should not be able to function.

i try on 6V also when i read the data sheet. yet it seem doesn't work. and i find a site and i struggle on that. it say use 12V. and the circuit is using data in and out. i do not know on it, too

and i can't post a link. the site is bryanchung .net?p=177

Don't you think that maybe if you used 12V and your Rset was too low, you just burned all your leds ?

but now i can light up the led but cannot control the led pattern. by the way, my circuit has a problem or not? if not, then i will try on the other direction such as the power or the resistor.

thank you for answer my question