Testing the system
In this last section of the chapter, we will connect an 8x8 LED matrix to display an alert if the sensor detects the presence of gas in the environment.
An LED matrix is a set of LEDs grouped into rows and columns. By turning on these LEDs, you can create graphics or text, which are widely used for billboards and traffic signs.
There is an electronic component for small-scale projects called an 8x8 LED matrix. It is composed of 64 LEDs arranged in eight rows and eight columns (see Figure 8.14):
Figure 8.14 – LED matrix 8x8
As you can see in the previous figure, the 8x8 LED matrix has pins to control the rows and columns, so it is impossible to control each LED independently.
This limitation implies having to use 16 digital signals and refreshes the image or text continuously. Therefore, the integrated MAX7219 and MAX7221 circuits have been created to facilitate this task; the circuits are almost identical and interchangeable...
