Then we will provide power to second row to turn on LED50 and wait for 1mSEC then will turn it OFF. Trick is, we will first provide power to first row to turn ON LED57 and wait for 1mSEC, and then we will turn it OFF. LetРІР‚в„ўs say for example, we want to only turn on LED57 and LED50 without turning on D49 and D58.

However this is not the case and LED will be actually turning ON and OFF constantly. That is if a LED goes ON and OFF continuously at the rate of 30HZ or more. The human eye cannot capture a frequency more than 30 HZ. Here we are explaining the Multiplexing briefly. We have already discussed this Multiplex Technique in 8x8 LED Matrix in detail go through that article for detailed explanation. To avoid that we use a technique called Multiplexing. But doing so will not only turn on D57, D50 but also D49, D58. Now for turning both LED57 and LED50 on, we need to power PIN0, PIN1 and ground the PIN8, PIN9. Now letРІР‚в„ўs say we want to turn ON LED57 then we need to power PIN0 of UNO and ground the PIN-8 of UNO.

LetРІР‚в„ўs put them together to see how they work together and the final Circuit for Scrolling 8x8 LED Matrix display will look like this:Р”Вriving 8x8 LED Matrix using Multiplexing: Since now you know how Common Positive and Common Negative works. The same process goes for all the other seven common negative columns. Now if we need to ground any LED in the first column then we will ground the PIN-A1 (NEGATIVE7) of the MATRIX, and it will ground all the LEDs in first column. One should pay attention to these pins while soldering the LEDs on Perfboard. So in 8x8 LED matrix, all the negative terminals of the LEDs in any column are brought together to form eight Common Negative Terminals, like all the negative terminals in first column are connected together to the PIN-A1 (NEGATIVE7). We need to ground the LEDs negatives to glow them. This is not over yet and just leaving the MATRIX ROWS with positive supply will not yield anything. Likewise if we want to glow any LED (or all) in any ROW then we need to power the corresponding Common Positive Terminal Pin of that respective Row. Now if we want glow one or all LEDs in the first ROW of matrix, then we should power the PIN0 of LED Matrix. Consider the first row, as seen in the figure, 8 LEDs from D57 to D64 have a common positive terminal and are denoted by РІР‚ВPOSITIVE0РІР‚в„ў. So for 8 rows we have 8 common positive terminals. For each row, there is one Common Positive Terminal for all 8 LED in that row. Over those rows and columns, all the positive terminals in a row are brought together.

There are 64 LEDs arranged in a matrix form.

Using a scrolling led badge