I will give a demonstration of how to use both methods in the examples below Using procedural programming You only need to input the required data to be displayed on the LED matrix. Using libraries is easiest way to get the required result because there is no need of worrying about detailed programming. One is using procedural programming to send the data bit by bit and the second way is to use previously written libraries for this chip. There are two ways of using the MAX7219 chip to control LED matrix. Controlling the 8×8 LED matrix using MAX7219 and Arduino. Never connect more than four led matrices directly to the microcontroller and always keep the brightness less than 50% to avoid destroying the microcontroller’s voltage regulator. LED matrix displays have a fairly high current draw and can use up to 1A if the brightness is set to maximum.Īlways use an external power supply for the display. The maximum power that the Arduino Uno can safely deliver when powered from USB is around 400 mA at 5 V. In this case we are using it to control 8×8 LED matrix.īelow is the diagram and description for each pin of the MAX7219 IC. The MAX7219 is a 24-pin IC designed as a serial input common-cathode display driver used to interface microcontrollers to 7-segment numeric LED displays of up to 8 digits, bar-graph displays or 64 individual LEDs. In addition, you can even daisy chain multiple MAX7219 chips for bigger displays without a need for extra I/O pins. To solve this problem, we can use the MAX7219 IC to drive the 64 LEDs using only 3 wires to interface it to a microcontroller. This is way too many pins for controlling a single device.
In order to control the 8×8 LED matrix directly with a microcontroller, you need to connect each row and each column to a digital pin, which means you would need 16 I/O pins.
Using this concept, the microcontroller turns ON the required LEDs in a row or column, one row or one column after the other, cycling through all rows or columns to turn on the required LEDs, at a rate greater than 20ms which tricks human eyes into seeing the designated LEDs appear to be ON at the same time! Using the MAX7219 IC to control 8×8 LED matrix. Our eyes remember a flash of light for approximately 20ms, so when you continuously flash a light at a rate of or faster than 20ms, then it appears that the light never goes off. To create the visual effect where all designated LEDs appear to be on at the same time, a vision persistence method is used.
It’s not possible to turn multiple LEDs in different rows and columns ON and keep them ON at the same time.
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