Chapter 9 Potentiometer & LED

We have already learned about the use of ADC and PWM. In this chapter, we will learn how to use a potentiometer to control the brightness of LED.

Project 9.1 Soft Light

In this project, we will make a soft light. We will use an ADC Module to read ADC values of a potentiometer and map it to duty cycle of the PWM used to control the brightness of a LED. Then you can change the brightness of a LED by adjusting the potentiometer.

Component List

ESP32-S3-WROOM x1
GPIO Extension Board x1
830 Tie-Points Breadboard x1
Resistor 220Ω x1
Potentiometer(10k) x1
LED x1
Jumper Wire x5

Connect

Code

Move the program folder Super_Starter_Kit_for_ESP32_S3/Python/Python_Codes to disk(D) in advance with the path of “D:/Micropython_Codes”.

Open “Thonny”, click This computer/D:/Micropython_Codes/09.1_Soft_LED and double click “Soft_LED.py”.

09.1_Soft_LED

Click “Run current script”. Rotate the handle of potentiometer and the brightness of LED will change correspondingly.

The following is the code:

from machine import Pin,PWM,ADC
import time

pwm =PWM(Pin(14,Pin.OUT),1000)
adc=ADC(Pin(1))
adc.atten(ADC.ATTN_11DB)
adc.width(ADC.WIDTH_12BIT)

def remap(value,oldMin,oldMax,newMin,newMax):
    return int((value)*(newMax-newMin)/(oldMax-oldMin))

try:
    while True:
        adcValue=adc.read()
        pwmValue=remap(adcValue,0,4095,0,1023)
        pwm.duty(pwmValue)
        print(adcValue,pwmValue)
        time.sleep_ms(100)
except:
    pwm.deinit()

In the code, read the ADC value of the potentiometer. The ADC value range is 0-4095. However, the default input range of the duty() function is 0-1023. Therefore, we need to write a remap() function to map the read ADC value to a value that conforms to the input range of the duty() function.

Project 9.2 Soft Colorful Light

In this project, 3 potentiometers are used to control the RGB LED and in principle it is the same as the Soft Light project. Namely, read the voltage value of the potentiometer and then convert it to PWM used to control LED brightness. Difference is that the original project only controlled one LED, but this project required (3) RGB LEDs.

Component List

ESP32-S3-WROOM x1
GPIO Extension Board x1
830 Tie-Points Breadboard x1
Resistor 220Ω x3
Potentiometer(10k) x3
LED-RGB x1
Jumper Wire x13

Connect

Code

Open “Thonny”, click This computer/D:/Micropython_Codes/09.2_Soft_Colorful_Light and double click “Soft_Colorful_Light.py”.

09.2_Soft_Colorful_Light

Click “Run current script”, rotate one of the potentiometers, The corresponding led colors will change: 38 control red, 39 control green, 40 control blue.

The following is the program code:

from machine import Pin,PWM,ADC
import time

pwm0=PWM(Pin(40,Pin.OUT),10000)
pwm1=PWM(Pin(39,Pin.OUT),10000)
pwm2=PWM(Pin(38,Pin.OUT),10000)
adc0=ADC(Pin(12))
adc1=ADC(Pin(13))
adc2=ADC(Pin(14))
adc0.atten(ADC.ATTN_11DB)
adc1.atten(ADC.ATTN_11DB)
adc2.atten(ADC.ATTN_11DB)
adc0.width(ADC.WIDTH_12BIT)
adc1.width(ADC.WIDTH_12BIT)
adc2.width(ADC.WIDTH_12BIT)

def remap(value,oldMin,oldMax,newMin,newMax):
    return int((value)*(newMax-newMin)/(oldMax-oldMin))

try:
    while True:
        pwm0.duty(1023-remap(adc0.read(),0,4095,0,1023))
        pwm1.duty(1023-remap(adc1.read(),0,4095,0,1023))
        pwm2.duty(1023-remap(adc2.read(),0,4095,0,1023))
        time.sleep_ms(100)
except:
    pwm0.deinit()
    pwm1.deinit()
    pwm2.deinit()

In the code, read the ADC value of 3 potentiometers and map it into PWM duty cyc le to control the control 3 LEDs with different color of RGBLED, respectively.