The i.MX6ULL Terminator development board is equipped with an LED light, and turn on the schematic diagram of the bottom board ("i.MX6UL Terminator CD Information\03_Development Board Hardware Information\01_Development Board Schematic Diagram\pdf\ itopmx6ul_terminator_v1_0. pdf”), the schematic diagram is shown in Figure 1:
It can be seen from the figure above that one section of LED2 is connected to a 3.3V power supply, and the other end is connected to the GPIO_3 (CPU's GPIO1_IO03) pin. When the GPIO1_IO03 pin outputs low level (0), LED2 will be lit, when GPIO1_IO03 When the pin outputs high level (1), LED2 will be off.
