Raspberry Pi Pico with Anemometer: Measure Wind Speed (Arduino IDE)

Learn how to interface an anemometer to measure wind speed with the Raspberry Pi Pico. We’ll cover how to power and connect the sensor to the Pico, and write a simple code to get wind speed values in different units. The Raspberry Pi Pico board will be programmed using Arduino IDE.

Raspberry Pi Pico with Wind Sensor - Arduino IDE

New to the Raspberry Pi Pico? Check out our eBook: Learn Raspberry Pi Pico with MicroPython.

Table of Contents

Throughout this guide, we’ll cover the following topics:

Introducing the Anemometer
- Anemometer Technical Details
Anemometer Pinout
Connecting the Anemometer to the Raspberry Pi Pico
Raspberry Pi Pico with the Anemometer – Measure Wind MicroPython Speed Code

Raspberry Pi Pico with Arduino ODE

You need to install the Raspberry Pi Pico boards on Arduino IDE and you must know how to upload code to the board. Check out the following tutorial first if you haven’t already:

Programming Raspberry Pi Pico with Arduino IDE

Introducing the Anemometer

An anemometer is a device that allows us to measure wind speed. It is commonly used in weather stations.

Using this sensor is quite easy. It outputs an analog signal, whose voltage is proportional to the wind speed. We’re using an anemometer with three cups like the one in the picture below.

Anemometer Technical Details

Depending on the manufacturer, the anemometer may have different characteristics. For example, these are the characteristics of the anemometer used in this guide:

Input voltage: 12-24V DC
Output voltage: 0-5V
Measurement range: 0-32.4m/s
Resolution: +/- 0.3m/s

This means that when the analog signal is 0, the wind speed is 0. However, in my case, after powering the sensor and applying a voltage regular, I noticed that when the anemometer was not moving, the output voltage was 0,033V and not 0V.

Raspberry Pi Pico Measure Voltage from Wind Sensor with no wind

So, I consider this to be the lowest value measured when the sensor is not moving. I recommend you do the same and figure out the minimum value read from the sensor using a multimeter.

These details might be different depending on the manufacturer. So, you need to take that into account when converting the analog signal to wind speed.

Anemometer Pinout

The anemometer comes with three wires:

Blue Wire	Signal
Black Wire	GND
Brown Wire	Power

Connecting the Anemometer to the Raspberry Pi Pico

The anemometer requires an input voltage of at least 12V. So, you can’t power it directly from the Raspberry Pi Pico, you need an external power source.

We’re powering the sensor using a 12V power adapter and connecting it to the anemometer using a power jack. You can use any other suitable power source.

Converting the Data Signal from 5V to 3.3V

In the case of my sensor, it operates in the range of 0 to 5V. However, the Raspberry Pi Pico analog pins can only read a maximum of 3.3V. So, we need to convert the 5V signal to a 3.3V signal. To do that, we can use a voltage divider.

Note: if you’re using an anemometer like the one from Adafruit, you don’t need to worry about this because the maximum output voltage is 2V.

A voltage divider is a simple circuit that reduces a large voltage into a smaller one. Using 2 resistors and an input voltage, we can create an output voltage that is a fraction of the input. Below you can see the formula that you need to use to calculate the resistors that you need in your circuit:

If we use a 1k Ohm (R1) and a 2k Ohm (R2) resistor, we’ll get a maximum output of 3.3V, which is the maximum that the Raspberry Pi Pico can read.

So, here’s what the voltage divider circuit looks like (in which 5V is the maximum value of the sensor data pin):

You can use any other combination of resistors, but you need to take into account the maximum output voltage allowed by the combination of resistors used.

Learn more here: How to Level Shift 5V to 3.3V

Wiring the Circuit: Raspberry Pi Pico with Anemometer

Raspberry Pi Pico with Anemometer Wind Sensor Circuit

Here’s a list of the parts you need for this tutorial:

You can use the following diagram as a reference to wire the sensor to the board. Don’t forget to connect the GND pins together.

Raspberry Pi Pico with Wind Sensor Anemometer Circuit Diagram

We’re connecting the data pin to the Raspberry Pi Pico GPIO 26. Other pins you can use are GPIOs 27 and 28.

If you’re using an anemometer like the one from Adafruit that outputs a maximum of 2V, you can connect the output pin directly to the Raspberry Pi Pico analog pin (you don’t need the voltage divider).

Black Wire	12V power source (+)
Blue Wire	Connect to Pico analog pin (via voltage divider, if needed), we’re using GPIO 26.
Brown Wire	GND of the Pico board and GND of the power source

Raspberry Pi Pico with Anemometer – Measure Wind Speed Arduino Code

The following code reads the analog signal from the anemometer and converts it into wind speed.

You can upload the following code to your Raspberry Pi Pico. You may need to modify some of the variables depending on the parameters of your anemometer.

/*********
  Rui Santos & Sara Santos - Random Nerd Tutorials
  Complete project details at https://RandomNerdTutorials.com/raspberry-pi-pico-anemometer-arduino/

  Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files.
  The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*********/

// Constants (Change the following variables if needed)
const int anemometerPin = 26;  // GPIO pin connected to anemometer (analog pin)
const float minVoltage = 0.033;  // Voltage corresponding to 0 m/s
const float maxVoltage = 3.3;  // Voltage corresponding to 32.4 m/s (max speed) (when using voltage divider)
const float maxWindSpeed = 32.4; // Maximum wind speed in m/s

// Conversion factors
const float mps_to_kmh = 3.6;   // 1 m/s = 3.6 km/h
const float mps_to_mph = 2.23694; // 1 m/s = 2.23694 mph

void setup() {
  Serial.begin(115200);  
}

void loop() {
  // Read analog value from anemometer (ADC value between 0-4095 on RPi Pico for 0-3.3V)
  int adcValue = analogRead(anemometerPin);
  Serial.print(adcValue);
  
  // Convert ADC value to voltage (by default, code sets 10-bit resolution: 0-1023 ADC range is 0-3.3V)
  float voltage = (adcValue / 1023.00) * 3.3;
  
  // Ensure the voltage is within the anemometer operating range
  if (voltage < minVoltage) {
    voltage = minVoltage;
  } else if (voltage > maxVoltage) {
    voltage = maxVoltage;
  }
  
  // Map the voltage to wind speed
  float windSpeed_mps = ((voltage - minVoltage) / (maxVoltage - minVoltage)) * maxWindSpeed;

  // Convert wind speed to km/h and mph
  float windSpeed_kmh = windSpeed_mps * mps_to_kmh;
  float windSpeed_mph = windSpeed_mps * mps_to_mph;

  // Print wind speed
  Serial.print("Wind Speed: ");
  Serial.print(windSpeed_mps);
  Serial.print(" m/s, ");
  Serial.print(windSpeed_kmh);
  Serial.print(" km/h, ");
  Serial.print(windSpeed_mph);
  Serial.println(" mph");
  
  delay(1000); 
}

View raw code

How does the Code Work?

First, define the pin where you’re reading the sensor, the minimum and the maximum output voltage of the sensor, and the maximum wind speed.

// Constants (Change the following variables if needed)
const int anemometerPin = 26;  // GPIO pin connected to anemometer (analog pin)
const float minVoltage = 0.033;  // Voltage corresponding to 0 m/s
const float maxVoltage = 3.3;  // Voltage corresponding to 32.4 m/s (max speed) (when using voltage divider)
const float maxWindSpeed = 32.4; // Maximum wind speed in m/s

These are the parameters for our sensor. Yours might be different. When we’re using the voltage divider, the maximum voltage that the Raspberry Pi Pico will read is 3.3V, which will correspond to the maximum wind speed. When the sensor is not moving, it outputs a voltage of 0.033 (read on the voltage divider output), so we consider that the minimum value.

Then, we have the conversion factors to convert the wind speed from m/s to km/h and mph.

// Conversion factors
const float mps_to_kmh = 3.6;   // 1 m/s = 3.6 km/h
const float mps_to_mph = 2.23694; // 1 m/s = 2.23694 mph

In the setup(), we initialize the Serial Monitor.

void setup() {
  Serial.begin(115200);  
}

In the loop(), we get new readings from the sensor every second.

First, we read the value on the ADC pin and convert it to a voltage value. By default, the code sets a 10-bit resolution for the analog signals, so the maximum value that the Pico can read on the analog pin is 1023 that corresponds to 3.3V. So, we can convert the value to a voltage using the following line:

float voltage = (adcValue / 1023) * 3.3;

Then, we have the following condition to check if the values read are within the defined range.

if (voltage < minVoltage) {
  voltage = minVoltage;
} else if (voltage > maxVoltage) {
  voltage = maxVoltage;
}

Next, we can easily map the obtained voltage to a wind speed value (alternatively, you can use the Arduino map() function).

float windSpeed_mps = ((voltage - minVoltage) / (maxVoltage - minVoltage)) * maxWindSpeed;

Then, we convert the values obtained to km/h and mph.

// Convert wind speed to km/h and mph
float windSpeed_kmh = windSpeed_mps * mps_to_kmh;
float windSpeed_mph = windSpeed_mps * mps_to_mph;

Finally, we print the obtained results.

  // Print wind speed
  Serial.print("Wind Speed: ");
  Serial.print(windSpeed_mps);
  Serial.print(" m/s, ");
  Serial.print(windSpeed_kmh);
  Serial.print(" km/h, ");
  Serial.print(windSpeed_mph);
  Serial.println(" mph");
  
  delay(1000); 
}

Upload the code to the Raspberry Pi Pico.

To upload code to the Raspberry Pi Pico, it needs to be in bootloader mode.

If the Raspberry Pi is currently running MicroPython firmware, you need to manually put it into bootloader mode. For that, connect the Raspberry Pi Pico to your computer while holding the BOOTSEL button at the same time.

For future uploads using Arduino IDE, the board should go automatically into bootloader mode without the need to press the BOOTSEL button.

Now, select your COM port in Tools > Port. It may be the case that the COM port is grayed out. If that’s the case, don’t worry it will automatically find the port once you hit the upload button.

Upload the code.

If you don’t know how to upload code to the Raspberry Pi Pico using Arduino IDE, check this tutorial: Programming the Raspberry Pi Pico with Arduino IDE.

Demonstration

After uploading the code to the board, you can select the Serial Port at the top of the Arduino IDE and open the Serial Monitor at a baud rate of 115200.

You should get wind sensor data on the Serial Monitor every second.