Understanding Automatic Street Light Using LDR (ADC) | Raspberry Pi Pico With Micropython | Part-6

Summary

In this video, the process of setting up an automatic street light using a Raspberry Pi Pico and an LDR (light-dependent resistor) is demonstrated. The circuit uses a voltage divider with the LDR and a 1K resistor, and the Raspberry Pi's analog-to-digital pins to monitor light intensity. An LED is connected to indicate when the light level drops below a set threshold, automatically turning on the street light. The video also covers the necessary coding in MicroPython using Thonny IDE, object creation for the LED and ADC, and setting conditions for controlling the LED based on light intensity readings.

Takeaways

• 🔌 The video discusses using an ADC (Analog to Digital Converter) with the Raspberry Pi Pico, which has only three ADC pins.
• 🛠️ The project involves creating an automatic street light by using an LDR (Light Dependent Resistor) and a 1K resistor in a voltage divider circuit.
• ⚡ The LDR is connected to 3.3V and the resistor is connected to ground. The midpoint of this circuit is connected to ADC pin GPIO 26 (ADC 0).
• 💡 An LED is added to the circuit, connected to GPIO pin 15 (General pin number 20), to control light intensity.
• 🖥️ To complete the circuit, two resistors, an LDR, an LED, and jumper wires are needed. The LDR-resistor combination forms the voltage divider.
• 📂 On the software side, the Raspberry Pi Pico is connected to a laptop via USB, and code is written using the Thonny IDE.
• 💻 The Python code imports the necessary modules (Pin, ADC) from the machine module and creates objects for both the LED and the ADC.
• 🔢 The ADC reads an unsigned 16-bit integer value ranging from 0 to 65,535, which corresponds to 0 to 3.3V from the LDR circuit.
• 🔄 The program uses a while loop and conditional statements to control the LED based on the light intensity value from the ADC.
• 🌃 The circuit can automatically switch the LED on or off based on light intensity, simulating an automatic street light functionality.

Q & A

What is the primary component being discussed in this video?

The primary component being discussed is the ADC (Analog to Digital Converter) in Raspberry Pi Pico.

How many analog-to-digital converter pins are available on the Raspberry Pi Pico?

There are three analog-to-digital converter (ADC) pins available on the Raspberry Pi Pico.

What components are used to create the voltage divider circuit in this project?

An LDR (Light Dependent Resistor) and a 1K resistor are used to create the voltage divider circuit.

How is the voltage divider circuit connected to the Raspberry Pi Pico?

One terminal of the LDR is connected to 3.3 volts, the other end of the resistor is connected to ground, and the meeting point between the LDR and resistor is connected to GPIO pin 26 (ADC0) on the Raspberry Pi Pico.

What is the function of the LED in this project?

The LED is used to indicate when the light intensity is below a certain threshold, simulating an automatic street light system.

Which pin is the LED connected to in the Raspberry Pi Pico?

The LED is connected to GPIO pin 15 (pin 20 on the board).

What software is used to write and upload the code to the Raspberry Pi Pico?

The Thonny IDE is used to write and upload the code to the Raspberry Pi Pico.

What Python functions are imported to control the ADC and the LED?

The 'Pin' and 'ADC' functions are imported from the 'machine' module, and the 'sleep' function is imported to control timing.

How is the analog value read from the LDR converted into a digital value?

The ADC reads the analog value from the LDR and converts it into a 16-bit unsigned integer ranging from 0 to 65,535, which corresponds to 0 to 3.3 volts.

How does the code determine when to turn the LED on or off?

The code uses a conditional statement that checks if the light intensity value (read by the ADC) is less than 2000. If it is, the LED is turned on, otherwise, it remains off.

Outlines

00:00

💡 Introduction to ADC on Raspberry Pi Pico

The video introduces the concept of an Analog to Digital Converter (ADC) on the Raspberry Pi Pico, which has three ADC pins. It explains the setup of a circuit that uses an LDR (Light Dependent Resistor) and a 1K resistor to form a voltage divider circuit. The LDR is connected to 3.3 volts, and the resistor is grounded. The midpoint of the voltage divider is connected to pin GP26 (ADC0) of the Raspberry Pi Pico. An LED is connected to GP15, and the objective is to control the streetlight automatically by sensing light intensity.

05:01

🔧 Circuit Assembly and Pin Connections

The speaker details the assembly of the circuit, including the required components: two resistors, one LDR, one LED, and two jumper wires. The steps involve connecting the LDR and resistor in a voltage divider configuration and making the necessary connections to the Raspberry Pi Pico pins (GP26 for the analog input and GP15 for the LED control). The video highlights the importance of following the provided circuit diagram and ensuring connections to power, ground, and signal pins for proper operation.

🖥️ Coding for ADC and LED Control

The video moves on to coding, demonstrating how to connect the Raspberry Pi Pico to a computer via USB and open the Thonny IDE. It explains importing the necessary modules (`Pin`, `ADC`, and `sleep`) from the machine module and shows how to create objects for controlling the LED and reading data from the ADC pin. The code reads values from the ADC pin (GP26) and checks the light intensity, preparing the system for automatic streetlight control based on sensor readings.

📝 Writing the ADC Reading Logic

The coding process continues with the explanation of reading values from the ADC. The ADC object reads a 16-bit unsigned integer (0 to 65,535) representing a voltage range from 0 to 3.3V. The speaker checks the light intensity by printing the values from the sensor and demonstrates how different light conditions (covering the sensor, exposing it to bright light) affect the ADC readings, which range from around 3000 in normal light to lower values when obstructed.

⚙️ Implementing the Automatic Streetlight Logic

In this section, the video introduces a while loop that continuously reads the light intensity from the ADC. A variable (`data`) is used to store the ADC values, and an if-else statement checks if the value drops below 2000 (indicating low light). If the light intensity is low, the LED turns on, simulating the streetlight turning on automatically. The code also includes a small delay and an else condition to turn off the LED when there is sufficient light.

🔄 Testing the Code and Demonstrating Results

The video concludes with a demonstration of the code in action. The ADC values are printed in real-time, and the LED turns on or off depending on the light intensity. The speaker shows that when the light intensity is less than 2000 (when the sensor is covered), the LED turns on, mimicking an automatic streetlight turning on during darkness. Removing the obstruction or increasing the light causes the LED to turn off, showing that the streetlight is not needed.

📢 Conclusion and Next Steps

The video wraps up by summarizing the project, noting that the automatic streetlight system works by using an ADC to measure light intensity. The video encourages viewers to subscribe to the channel for more tutorials and hints at future projects involving Raspberry Pi Pico and similar components.

Keywords

💡ADC (Analog to Digital Converter)

An ADC is a device that converts an analog signal, such as voltage, into a digital signal that a microcontroller like the Raspberry Pi Pico can read. In the video, the ADC is used to measure the voltage across an LDR (light-dependent resistor) to determine light intensity. The ADC on the Raspberry Pi Pico has three pins, and in this case, ADC 0 (GPIO 26) is used.

💡LDR (Light Dependent Resistor)

An LDR is a type of resistor whose resistance changes based on the amount of light it is exposed to. In the video, the LDR is part of a voltage divider circuit, which helps in detecting light levels. This is used to automate the switching of an LED light based on light intensity, making it a key component in the automatic street light control project.

💡Voltage Divider Circuit

A voltage divider is a simple circuit that divides the input voltage into smaller outputs based on the resistances in the circuit. In this project, an LDR and a 1K resistor form the voltage divider, where the output voltage is measured by the ADC pin to monitor light intensity. This configuration is essential for converting the LDR’s changing resistance into a measurable voltage.

💡GPIO (General Purpose Input/Output)

GPIO pins are versatile pins on the Raspberry Pi Pico that can be programmed for input (receiving data) or output (sending data). In this video, GPIO 26 (ADC 0) reads the analog signal from the LDR, and GPIO 15 controls the LED. These pins allow the Raspberry Pi Pico to interface with various components in the circuit.

💡Raspberry Pi Pico

The Raspberry Pi Pico is a microcontroller board based on the RP2040 chip, used to control electronic projects. In this video, the Pico is programmed to read light intensity from an LDR using its ADC pins and to turn an LED on or off based on the readings. It is central to automating the street light system described in the project.

💡LED (Light Emitting Diode)

An LED is a semiconductor device that emits light when current flows through it. In this project, the LED is used to simulate an automatic street light, which turns on when the light intensity detected by the LDR drops below a certain threshold. The GPIO pin 15 on the Raspberry Pi Pico controls the LED.

💡Python (Programming Language)

Python is the programming language used to code the logic for this project. The video uses Python to control the ADC pins and GPIO pins of the Raspberry Pi Pico. The program checks the light intensity, and if the value is below a set threshold, it activates the LED. This demonstrates how Python can be used to interact with hardware components.

💡Thonny IDE

Thonny is an Integrated Development Environment (IDE) used to write and execute Python code, especially for microcontroller projects like this one. In the video, Thonny is used to write and upload the code to the Raspberry Pi Pico, allowing the user to program the ADC and GPIO functionalities necessary for controlling the automatic street light.

💡Unsigned 16-bit Integer

An unsigned 16-bit integer is a data type that can represent whole numbers between 0 and 65,535. The video mentions that the ADC readings from the LDR are represented as unsigned 16-bit integers, which map the 0-3.3V range to a value between 0 and 65,535. This is essential for understanding how the light intensity is translated into a digital value.

💡Conditional Statement (if-else)

A conditional statement is a basic programming structure that executes different actions based on whether a condition is true or false. In the video, an 'if' condition checks whether the light intensity is below a certain threshold (e.g., 2000). If true, the LED turns on, simulating the street light turning on when it's dark. If false, the LED remains off.

Highlights

Introduction to ADC (Analog to Digital Converter) in Raspberry Pi Pico.

Raspberry Pi Pico has three ADC pins; in this project, ADC 0 (GPU pin 26) is used.

An LDR (Light Dependent Resistor) and a 1K resistor form a voltage divider circuit for measuring light intensity.

The LDR is connected to 3.3V and the resistor is connected to ground; the meeting point goes to ADC 0.

The project aims to control an automatic streetlight based on light intensity.

An LED is used to represent the streetlight, connected to GPIO pin 15.

Required components for the circuit: two 1K resistors, one LDR, one LED, and two jumper wires.

Building the voltage divider circuit step-by-step with the LDR and resistor.

Using a jumper wire to connect the common pin to the ground in the circuit.

The analog signal from the voltage divider is sent to ADC pin 26 (GPIO pin 31).

Coding the project: Importing the necessary libraries from the machine module (Pin, ADC) and sleep function.

Creating objects for the LED and ADC to control GPIO pin 15 and read data from ADC pin 26.

The ADC object reads values from 0 to 65,535, mapping the range of 0 to 3.3V.

Using a while loop to continuously read light intensity values and control the LED.

Conditional logic: The LED turns on when the light intensity falls below a certain threshold (e.g., 2000).

Demonstrating the automatic streetlight by covering the LDR and observing the LED behavior.

Transcripts

in this video we will be discussing

about ADC analog to digital converter in

Raspberry Pi Pico

we have only three analog to digital

pins available

this is the circuit for our project

here there is an ldr and a resistor

1K resistor is used here

this series combination makes a voltage

divider circuit

and one terminal of the ldr is connected

to 3.3 volts

and the other end of the register is

connected to ground and the meeting

position that is coming over here

that is going to the analog pin that is

GPU 26 or ADC 0 is the PIN we are going

to use this time and to control

automatic street light by considering

the light intensity I have added an LED

and this led is connected to GTA 15.

that is General pin number 20 dot this

is a pin diagram of task Pico

this case one is board pin number 20.

that is GPU 50 and you can see ADC 0 is

marked here

that is GPA of 26. these are the pins we

are going to use in the circuit

let's now begin making the circuit

for completing the circuit we need to

resistors

1K resistors one ldr one LED and two

jumper wires

let's start building it

let me make a voltage divider circuit

first

just connected ldr over here I can make

it little bit closer somewhere like this

then from the same point I can use the

other pin just connecting into the

negative Trail

now this is a common pin here in Thane

my case and it is connected to negative

Trails so I have to make that connection

I'm using a jumper wire

all the third pin that is the ground

it is connecting to negative Trail your

ground

now that part is over

next one I need to give the signal

I wanted to take it from the common

terminal

this is a common 24th where the both ldr

and the resistor are meeting

I should go to ADC

that is GPA pin number 26.

let's find that that is exactly the

position 31 the position 31 at Pin

so you have to count it properly

I have to give the power is there at the

36 pin number

I'm connecting it to the other side of

the area

you can follow the circuit diagram which

is already provided

next I need to use this led make sure

that they are not touching

for this I need to take a connection

from gpo15 at

its 20th position

and taking action from here placing a

system and you can use the resistor

longest pin

that is the positive terminal should

connect to the terminal of the resistor

a negative can be connected to ground

we know that the ground this is a common

value from here

I can make a connection to here

now our circuit completed

look into the coding site for this make

sure that you have connected your

Raspberry Pi Pico with your laptop using

a USB cable

open your Tawny ID

create a new file for using ADC

you have to import pin

ADC from the machine module and we need

to use a sleep function also

that also you have to import

let's import those functions

simply you can use a comma to import to

functions from the same module

now we have imported the needed

functions

we have to create two objects one is for

the LED one is for the ADC object

let's create an object

for the LED there is an LED object is

created for the GPA pin number 15.

the same we have done in the circuit

let's create an object for the ADC pin

just use ADC because already we have

imported ADC from the machine

otherwise you have to keep machine ADC

this is one method you can actually use

it

but we already imported ADC run the

machine module we haven't imported the

entire module

that's why you can directly use ADC and

here you have to mention which pin we

are going to use

in this case we are using GPU pin number

26.

that is General pin number 31.

it is ADC 0 is the actually in the GPU

when you are considering that is GPU 26.

so we have created two objects

now we have to check what is the value

is coming then we can modify our main

code let me upload this code

now this time I can save into the

computer

I have a temporary folder in the text

you can give a name here just save that

so there is no error till

now so we have created the objects right

now

it is very easy ADC object read normally

in the esp32

we use read directly it will not work in

the case of Eco module

you have to say that underscore u60

now this is going to read in an integer

having unsigned integer 16-bit

that means it will read a value from 0

to 65 535.

that means it will map 0 to 3.3 volts in

a range or in a division from 0 to 65

535.

let's see what is the value is going to

show over here

so now the light intensity is showing

like somewhere the value is 3168.

somewhere the value is coming now I'm

just going to hold the sensor with my

hand repeat the same program

let's see what is the value is coming

I'm getting a lower value isn't it

now I can also use brighter light

then you can find the values again we'll

change that

we will be looking right now again it's

coming around 3000 somewhere the value

now we are going to use that to print

continuously and we have to get and we

can make an automatic street light by

measuring this value

for that I am using while loop

while through the data which I am taking

from the ADC object

I am creating a variable called Data

you can give any variable name ADC

ADC object read underscore steam means

unsigned 16-bit integer which gives a

range from 0 to 65

535 for a voltage 0 to 3 point

keep that in mind

we can just print the value now I got

the value somewhere around the normal

lighting condition

I am getting around the value 3000.

the light intensity has become less than

3000 somewhere value that is purely

depending upon my lighting condition and

I wanted to make the LED to be on

for that I'm using conditional statement

called if data

value is supposed to be less than I am

considering somewhere around 2000 for

this case

because normally my lighting conditional

am getting 3 000. I haven't given too

much light in my room I have to make the

LED object to be on here

maybe I can give a small delay 5 Seconds

else condition in order to make the LED

to be off

let's run this code and see what will be

the output

you can see the value is printing

somewhere around 3000 dot that is there

isn't enough lighting condition there

that's why the lady is not going to work

now I am going to cover this eldia

you can see the lighting value in

density is less than 2 000. it is

showing somewhere around 700 comma 800

dot now the value is less than two

thousand dot that's why this light is

automatically switched on

I remove my hand it becomes off

that means there is enough light there

at the street if it is going to be

darker now you can see the light is

going to be automatically switched on

okay I hope this lecture is clear for

you

see you on the next video

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