HOW to Detect Pressure with ESP32

Overview

In this kit, there is a Keyestudio thin-film pressure sensor. The thin-film pressure sensor composed of a new type of nano pressure-sensitive material and a comfortable ultra-thin film substrate, has waterproof and pressure-sensitive functions.

In the experiment, we determine the pressure by collecting the analog signal on the S end of the module. The smaller the ADC value, DAC value and voltage value, the greater the pressure; and the displayed results will shown on the Shell.

Working Principle

When the sensor is pressed by external forces, the resistance value of sensor will vary. We convert the pressure signals detected by the sensor into the electric signals through a circuit. Then we can obtain the pressure changes by detecting voltage signal changes.

Components

Connection Diagram

Test Code

# Import Pin, ADC and DAC modules.
from machine import ADC,Pin,DAC
import time

# Turn on and configure the ADC with the range of 0-3.3V 
adc=ADC(Pin(34))
adc.atten(ADC.ATTN_11DB)
adc.width(ADC.WIDTH_12BIT)

# Read ADC value once every 0.1seconds, convert ADC value to DAC value and output it,
# and print these data to “Shell”. 
try:
    while True:
        adcVal=adc.read()
        dacVal=adcVal//16
        voltage = adcVal / 4095.0 * 3.3
        print("ADC Val:",adcVal,"DACVal:",dacVal,"Voltage:",voltage,"V")
        time.sleep(0.1)
except:
    pass

Test Result

Connect the wires according to the experimental wiring diagram and power on. Click “Run current script”, the code starts executing. The “Shell” window will display the thin-film pressure sensor ADC value, voltage value and DAC value. When the thin-film is pressed by fingers, the analog value will decrease, as shown below. Press “Ctrl+C”or click“Stop/Restart backend” to exit the program.