# Investigation of an LED Strip Controller Based on a PWM Driver and a PIC Series Microcontroller
## 3 Results and Discussion
For the sake of the universality of the study, the change in the PWM signal was measured as a percentage, where 100% PWM was the maximum duration signal used in this study. Control of the PWM signal was performed programmatically in the microcontroller program code, by changing logic values from 0 to 4095. The dependence of the PWM signal characteristic on the logic values generated by the microcontroller is presented in Figure 8. As can be seen from the measurement results, when the logic values of the microcontroller changed from 1000 to 4000, the size of the PWM signal changed from 25 to 100%. When the percentage of the PWM signal was changed, this changed the power supply to the LED strips. As it can be seen from the research results, this dependence was linear. Such a result allows the use of a simpler (shorter) program code for controlling the PWM signal. Figure 2:0 Dependence of the reaction time on the length of the microcontroller command. In addition, it allows shortening the reaction time, because in the case of a simple linear dependence, the length of the microcontroller commands transmitted to the control contacts of the PWM driver is shortened. As the percentage of the PWM signal was shortened, the light flux decreased more and more. When you shorten the PWM signal, the electric current and voltage of the signal do not change, but when the PWM is shortened, the total power supplied to the LED strip decreases. The dependence of the light flux LED strip on the percentage of the PWM signal is presented in Figure 2:1 LED strips with a maximum light flux of 1000 lm were selected for this research. As can be seen from the research results, when the percentage of the PWM signal was changed from 10 to 100%, the light flux of the LED strip changed from 100 to 1000 lm. As can be seen from the results, in this case the dependence graph is close to straight. When the on-time percentage of the PWM signal was higher, the light flux of the LED strip was generally higher. This means that the LEDs were on for a longer time per cycle, therefore providing more light. The reason for this has to do with how the PWM signal controls the LEDs. When the PWM signal is on, the LEDs light up and use power. The longer the PWM signal is on per cycle, the more energy is transferred to the LEDs, and they shine with a brighter light flux. The linear dependence allows directly determining the level of light flux according to the percentage value of the PWM signal. This simplifies the control logic and programming by eliminating the need for complex mathematical operations or non-linear algorithms. Figure 2:2 The dependence of the percentage of the PWM signal on the PWM values of the microcontroller. Figure 2:3 Dependence of the LED light flux on the percentage of the PWM signal. As mentioned, the designed and tested LED controller has 16 power channels. Each channel can be connected to an LED strip of the corresponding capacity and its light flux can be controlled. The maximum power of one channel is 12 W. The PWM driver cannot generate such power directly; therefore, the power supply from the power source to the individual channels of the LED controller is modulated by the same law as the PWM signal change using MOSFET-type transistors. The results of studies of the dependence of the power of one channel on the percentage of the PWM signal are presented in Figure 2:4 As can be seen from the measurement results, the power of one channel changed from 1 to 12 W when the PWM signal was changed from 10 to 100%. It is worth noting that, in each specific case, the power of the power supply channel may vary depending on the characteristics of the power source used [2; 3; 4; 5]. During this research, how the light flux changed when the power of one power channel changed was studied. As mentioned, the power was changed by modifying the PWM signal.