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Lesson 25: Water Level Sensor Module

Note

The Raspberry Pi does not have analog input capabilities, so it needs a module like the PCF8591 ADC DAC Converter Module to read analog signals for processing.

In this lesson, we’ll learn how to read from a water level sensor using a Raspberry Pi. You’ll find out how to connect a water level sensor module to the PCF8591 for analog-to-digital conversion and monitor its output in real-time with Python.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Universal Maker Sensor Kit	94	Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction	Purchase Link
Raspberry Pi 5	BUY
Water Level Sensor Module	-
PCF8591 ADC DAC Converter Module	BUY

Wiring

../_images/Lesson_25_Water_Level_Sensor_Module_pi_bb.png

Code

import PCF8591 as ADC  # Import PCF8591 module
import time  # Import time for delay

ADC.setup(0x48)  # Initialize PCF8591 at address 0x48

try:
    while True:  # Continuously read and print
        print(ADC.read(1))  # Read from Water level sensor module at AIN1
        time.sleep(0.2)  # Delay of 0.2 seconds
except KeyboardInterrupt:
    print("Exit")  # Exit on CTRL+C

Code Analysis

Import Libraries:

This section imports necessary Python libraries. The PCF8591 library is used for interacting with the PCF8591 module, and time is for implementing delays in the code.
```
import PCF8591 as ADC  # Import PCF8591 module
import time  # Import time for delay
```
Initialize PCF8591 Module:

Here, the PCF8591 module is initialized. The address 0x48 is the I²C address of the PCF8591 module. This is necessary for the Raspberry Pi to communicate with the module.
```
ADC.setup(0x48)  # Initialize PCF8591 at address 0x48
```
Main Loop and Reading Data:

The try block includes a continuous loop that consistently reads data from the water level sensor module. The ADC.read(1) function captures the analog input from the sensor connected to channel 1 (AIN1) of the PCF8591 module. Incorporating a time.sleep(0.2) creates a 0.2-second pause between each reading. This not only helps in reducing CPU usage on the Raspberry Pi by avoiding excessive data processing demands, but also prevents the terminal from being overrun with rapidly scrolling information, making it easier to monitor and analyze the output.
```
try:
    while True:  # Continuously read and print
        print(ADC.read(1))  # Read from Water level sensor module at AIN1
        time.sleep(0.2)  # Delay of 0.2 seconds
```
Handling Keyboard Interrupt:

The except block is designed to catch a KeyboardInterrupt (like pressing CTRL+C). When this interrupt occurs, the script prints “exit” and stops running. This is a common way to gracefully exit a continuously running script in Python.
```
except KeyboardInterrupt:
    print("exit")  # Exit on CTRL+C
```