Automated plant watering system in Raspberry Pi - Mini Project: Build & Apply

Automated Plant Watering System

📖 Scenario: You have a small garden with a few plants. You want to build a simple program to help water your plants automatically when the soil is dry.This program will check soil moisture levels and decide if watering is needed.

🎯 Goal: Build a program that reads soil moisture levels for three plants, checks if the moisture is below a set threshold, and prints which plants need watering.

📋 What You'll Learn

Create a dictionary with plant names and their soil moisture levels.

Set a moisture threshold value to decide when to water.

Use a for loop to check each plant's moisture level against the threshold.

Print the names of plants that need watering.

💡 Why This Matters

🌍 Real World

Automated plant watering helps keep plants healthy by watering them only when needed, saving water and effort.

💼 Career

Understanding how to read sensor data and make decisions is useful in IoT (Internet of Things) and embedded systems jobs.

1

Create the soil moisture data

Create a dictionary called soil_moisture with these exact entries: 'Fern': 30, 'Cactus': 70, 'Bonsai': 45 representing the moisture levels of each plant.

Raspberry Pi

# Create the soil_moisture dictionary with given values
# Your code here

Hint

Use curly braces {} to create a dictionary with keys and values.

2

Set the moisture threshold

Create a variable called threshold and set it to 50. This will be the moisture level below which plants need watering.

Raspberry Pi

soil_moisture = {'Fern': 30, 'Cactus': 70, 'Bonsai': 45}
# Set the moisture threshold to 50
# Your code here

Hint

Just assign the number 50 to the variable threshold.

3

Check which plants need watering

Use a for loop with variables plant and moisture to iterate over soil_moisture.items(). Inside the loop, check if moisture is less than threshold and if so, add plant to a list called needs_watering. Create the list before the loop.

Raspberry Pi

soil_moisture = {'Fern': 30, 'Cactus': 70, 'Bonsai': 45}
threshold = 50

# Create an empty list called needs_watering
# Use a for loop to check moisture levels
# Your code here

Hint

Remember to create the list before the loop. Use append() to add plants to the list.

4

Print the plants that need watering

Write a print statement to display the text "Plants that need watering:" followed by the needs_watering list.

Raspberry Pi

soil_moisture = {'Fern': 30, 'Cactus': 70, 'Bonsai': 45}
threshold = 50

needs_watering = []
for plant, moisture in soil_moisture.items():
    if moisture < threshold:
        needs_watering.append(plant)

# Print the plants that need watering
# Your code here

Hint

Use print("Plants that need watering:", needs_watering) to show the result.

Practice

1.

What is the main purpose of an automated plant watering system using a Raspberry Pi?

easy

A. To control room temperature automatically

B. To water plants continuously without checking soil

C. To measure sunlight for plants

D. To water plants only when the soil is dry

Solution

1. Step 1: Understand the system goal

   The system uses sensors to check soil moisture.

2. Step 2: Identify the watering condition

   It waters plants only when soil is dry to save water.

3. Final Answer:

   To water plants only when the soil is dry -> Option D

4. Quick Check:

   Water only if dry = A [OK]

Hint: Focus on saving water by watering only when needed [OK]

Common Mistakes:

• Thinking it waters plants all the time
• Confusing soil moisture with sunlight
• Assuming it controls temperature

2.

Which of the following Python code snippets correctly sets up a GPIO pin 17 as an output to control a water pump?

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
# What goes here?

easy

A. GPIO.setup(17, GPIO.OUT)

B. GPIO.setup(17, GPIO.IN)

C. GPIO.output(17, GPIO.IN)

D. GPIO.output(17, GPIO.OUT)

Solution

1. Step 1: Identify pin mode setup

   GPIO.setup(pin_number, GPIO.OUT) sets pin as output.

2. Step 2: Choose correct function and mode

   GPIO.setup(17, GPIO.OUT) correctly sets pin 17 as output.

3. Final Answer:

   GPIO.setup(17, GPIO.OUT) -> Option A

4. Quick Check:

   Setup output pin = A [OK]

Hint: Use GPIO.setup(pin, GPIO.OUT) to set output pins [OK]

Common Mistakes:

• Using GPIO.IN instead of GPIO.OUT for output pins
• Calling GPIO.output instead of GPIO.setup to set mode
• Confusing pin numbers or modes

3.

What will be the output of this Python code controlling a pump based on soil moisture sensor reading?

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(17, GPIO.OUT)
soil_moisture = 300  # sensor value
if soil_moisture < 400:
    GPIO.output(17, GPIO.HIGH)
    print("Pump ON")
else:
    GPIO.output(17, GPIO.LOW)
    print("Pump OFF")

medium

A. SyntaxError

B. Pump OFF

C. Pump ON

D. No output

Solution

1. Step 1: Check soil moisture condition

   Value 300 is less than 400, so condition is true.

2. Step 2: Determine pump action and output

   GPIO.output sets pin HIGH and prints "Pump ON".

3. Final Answer:

   Pump ON -> Option C

4. Quick Check:

   300 < 400 triggers Pump ON [OK]

Hint: Compare sensor value to threshold to decide pump state [OK]

Common Mistakes:

• Misreading the comparison operator
• Confusing HIGH and LOW states
• Ignoring print output

4.

Identify the error in this Raspberry Pi watering system code snippet:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(17, GPIO.OUT)
soil_moisture = 500
if soil_moisture > 400
    GPIO.output(17, GPIO.LOW)
    print("Pump OFF")

medium

A. soil_moisture value is invalid

B. Missing colon (:) after if condition

C. GPIO.output should be GPIO.setup

D. Wrong GPIO pin number

Solution

1. Step 1: Check if statement syntax

   Python requires a colon (:) after the if condition.

2. Step 2: Identify missing colon error

   The code misses ':' after 'if soil_moisture > 400', causing syntax error.

3. Final Answer:

   Missing colon (:) after if condition -> Option B

4. Quick Check:

   if statement needs ':' = D [OK]

Hint: Always put ':' after if conditions in Python [OK]

Common Mistakes:

• Forgetting colon after if
• Confusing GPIO.output with GPIO.setup
• Assuming pin number is wrong

5.

You want to improve the watering system to water plants only if soil moisture is below 400 and only between 6 AM and 8 AM. Which Python code snippet correctly adds this time condition?

import datetime
now = datetime.datetime.now()
soil_moisture = 350
if soil_moisture < 400 and ???:
    print("Watering plants")
else:
    print("No watering")

hard

A. now.hour >= 6 and now.hour <= 8

B. now.hour > 6 or now.hour < 8

C. now.hour < 6 and now.hour > 8

D. now.hour == 6 or now.hour == 8

Solution

1. Step 1: Understand time range condition

   We want hours from 6 to 8 inclusive, so hour >= 6 and hour <= 8.

2. Step 2: Combine soil moisture and time conditions

   Use 'and' to check both soil moisture and time range.

3. Final Answer:

   now.hour >= 6 and now.hour <= 8 -> Option A

4. Quick Check:

   Check hour between 6 and 8 = B [OK]

Hint: Use 'and' with hour >= 6 and <= 8 for time range [OK]

Common Mistakes:

• Using 'or' instead of 'and' for time range
• Using strict inequalities excluding 6 or 8
• Checking only exact hours 6 or 8