We've all been there. That thing is close but how close? When you need to measure a meter-or-so distance with reasonable accuracy, the VCNL4200 Long Distance Proximity Sensor from Vishay can do that for you. It's excellent for robotic or motion-detection situations. And if perchance you also needed to measure the amount of light at the same time, you're in luck! The VCNL4200 can do that too, with it's built in ambient light sensor (ALS).

The VCNL4200 is a powerful two-in-one sensor, with a proximity sensor that works from 0 to 1.5m (59 inches) and light sensor with range of 0.003 to 1570 lux. It's the longest-range IR distance sensor we've seen other than the Sharp Analog distance sensors, and at a great price with I2C interface.

Note that while the chip itself is specced for 1.5 meter distance measurements, that depends a bit on optimal lighting situations and high power configuration. We've found that 50-100cm is a good range to expect, and you won't get a lot of accuracy/precision as the detection object gets farther away. We normally suggest ToF sensors for long precision measurements, but sometimes you want the low cost and simplicity of infrared. Also, you get a 'free' light sensor which ToF sensors don't contain.

"OK, finally I can get started on my proximity and light sensing project, but how do I use it?" you say. To make life easier so you can focus on your important work, we've taken the VCNL4200 and put it onto a breakout PCB along with support circuitry to let you use this little wonder with 3.3V (Feather/Raspberry Pi) or 5V (Arduino/ Metro328) logic levels.

Additionally, since it speaks I2C, you can easily connect it up with two wires (plus power and ground!). We've even included SparkFun qwiic compatible STEMMA QT connectors for the I2C bus so you don't even need to solder! Just wire up to your favorite micro and you can use our CircuitPython/Python or Arduino drivers to easily interface with the VCNL4200 and make approximate approximations of proximity in no time! QT Cable is not included, but we have a variety in the shop.

To give you some ability to tune your measurements for your situation, the VCNL4200 lets you adjust the integration time for both light sensing and proximity, IR LED power, duty cycle, multi-pulse, and sunlight-immunity. There's also interrupt output support for light or proximity measurement thresholds.

Default I2C address is 0x51.

Power Pins

• VIN - this is the power pin. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like Arduino, use 5V. It can be powered between from 3.3V to 5V.
• 3Vo - this is the 3.3V output from the onboard regulator.
• GND - common ground for power and logic.

I2C Logic Pins

• SCL - I2C clock pin, connect to your microcontroller's I2C clock line. This pin can use 3-5V logic, and there's a 10K pullup on this pin.
• SDA - I2C data pin, connect to your microcontroller's I2C data line. This pin can use 3-5V logic, and there's a 10K pullup on this pin.
• STEMMA QT - These connectors allow you to connect to development boards with STEMMA QT (Qwiic) connectors or to other things with various associated accessories.

Interrupt Pin

• INT - This is the interrupt pin. You can set up the sensor to pull this low when certain conditions are met such as proximity or lux level thresholds being crossed.

Power LED and Jumper

• Power LED - on the left side of the board, above the STEMMA QT connector, is the power LED, labeled on. It is a green LED.
• LED jumper - on the back of the board is a jumper for the power LED. It is labeled LED on the board silk. If you want to disable the power LED, cut the trace on this jumper.

It's easy to use the VCNL4200 with Python or CircuitPython, and the Adafruit_CircuitPython_VCNL4200 module. This module allows you to easily write Python code to read proximity and lux data.

You can use this driver with any CircuitPython microcontroller board or with a computer that has GPIO and Python thanks to Adafruit_Blinka, our CircuitPython-for-Python compatibility library.

CircuitPython Microcontroller Wiring

First wire up the sensor to your board exactly as follows. The following is the sensor wired to a Feather RP2040 using the STEMMA connector:

The following is the sensor wired to a Feather RP2040 using a solderless breadboard:

Python Computer Wiring

Since there are dozens of Linux computers/boards you can use, we will show wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported.

Here's the Raspberry Pi wired with I2C using the STEMMA connector:

Here's the Raspberry Pi wired with I2C using a solderless breadboard:

Python Installation of VCNL4200 Library

You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!

Once that's done, from your command line run the following command:

• pip3 install adafruit-circuitpython-vcnl4200

If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!

CircuitPython Usage

To use with CircuitPython, you need to first install the Adafruit_CircuitPython_VCNL4200 library, and its dependencies, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.

Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Your CIRCUITPY/lib folder should contain the following folders and file:

• adafruit_bus_device/
• adafruit_register/
• adafruit_vcnl4200.mpy

Python Usage

Once you have the library pip3 installed on your computer, copy or download the following example to your computer, and run the following, replacing code.py with whatever you named the file:

python3 code.py

Example Code

If running CircuitPython: Once everything is saved to the CIRCUITPY drive, connect to the serial console to see the data printed out!

If running Python: The console output will appear wherever you are running Python.

# SPDX-FileCopyrightText: Copyright (c) 2024 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time

import board

import adafruit_vcnl4200

i2c = board.I2C()

sensor = adafruit_vcnl4200.Adafruit_VCNL4200(i2c)

while True:
    print(f"Proximity is: {sensor.proximity}")
    print(f"Ambient is: {sensor.lux}")
    time.sleep(0.1)

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# SPDX-FileCopyrightText: Copyright (c) 2024 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time

import board

import adafruit_vcnl4200

i2c = board.I2C()

sensor = adafruit_vcnl4200.Adafruit_VCNL4200(i2c)

while True:
    print(f"Proximity is: {sensor.proximity}")
    print(f"Ambient is: {sensor.lux}")
    time.sleep(0.1)

First, the sensor is instantiated over I2C. Then, in the loop, the proximity and lux readings are printed to the serial monitor. You'll see these readings change depending on the proximity of objects in front of the sensor and the amount of ambient light that the sensor is exposed to.

Using the VCNL4200 breakout with Arduino involves wiring up the breakout to your Arduino-compatible microcontroller, installing the Adafruit_VCNL4200 library, and running the provided example code.

Wiring

Wire as shown for a 5V board like an Uno. If you are using a 3V board, like an Adafruit Feather, wire the board's 3V pin to the sensor VIN.

Here is an Adafruit Metro wired up to the sensor using the STEMMA QT connector:

Here is an Adafruit Metro wired up using a solderless breadboard:

Library Installation

You can install the Adafruit_VCNL4200 library for Arduino using the Library Manager in the Arduino IDE.

Click the Manage Libraries ... menu item, search for Adafruit_VCNL4200, and select the Adafruit VCNL4200 library:

If asked about dependencies, click "Install all".

If the "Dependencies" window does not come up, then you already have the dependencies installed.

Full Test Example

// SPDX-FileCopyrightText: 2024 ladyada for Adafruit Industries
//
// SPDX-License-Identifier: MIT

#include "Adafruit_VCNL4200.h"

Adafruit_VCNL4200 vcnl4200;

void setup() {
  Serial.begin(115200);
  while (!Serial) {
    delay(10); // wait for native USB
  }

  Serial.println("Adafruit VCNL4200 ALS simple test");

  if (!vcnl4200.begin()) {
    Serial.println("Could not find a valid VCNL4200 sensor, check wiring!");
    while (1) {
      delay(10);
    }
  }
  Serial.println("VCNL4200 found!");

  vcnl4200.setALSshutdown(false);
  vcnl4200.setALSIntegrationTime(VCNL4200_ALS_IT_100MS);
  vcnl4200.setALSPersistence(VCNL4200_ALS_PERS_2);

  vcnl4200.setProxShutdown(false);
  vcnl4200.setProxHD(false);
  vcnl4200.setProxLEDCurrent(VCNL4200_LED_I_200MA);
  vcnl4200.setProxIntegrationTime(VCNL4200_PS_IT_8T);
}

void loop() {
  // Read the proximity sensor data
  uint16_t proxData = vcnl4200.readProxData();
  Serial.print("Prox Data: ");
  Serial.println(proxData);
  // Read the ambient light sensor (ALS) data
  uint16_t alsData = vcnl4200.readALSdata();
  Serial.print("ALS Data: ");
  Serial.print(alsData);
  // Read the raw white sensor data
  uint16_t whiteData = vcnl4200.readWhiteData();
  Serial.print(", White Data: ");
  Serial.println(whiteData);

  delay(100);
}

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// SPDX-FileCopyrightText: 2024 ladyada for Adafruit Industries
//
// SPDX-License-Identifier: MIT

#include "Adafruit_VCNL4200.h"

Adafruit_VCNL4200 vcnl4200;

void setup() {
  Serial.begin(115200);
  while (!Serial) {
    delay(10); // wait for native USB
  }

  Serial.println("Adafruit VCNL4200 ALS simple test");

  if (!vcnl4200.begin()) {
    Serial.println("Could not find a valid VCNL4200 sensor, check wiring!");
    while (1) {
      delay(10);
    }
  }
  Serial.println("VCNL4200 found!");

  vcnl4200.setALSshutdown(false);
  vcnl4200.setALSIntegrationTime(VCNL4200_ALS_IT_100MS);
  vcnl4200.setALSPersistence(VCNL4200_ALS_PERS_2);

  vcnl4200.setProxShutdown(false);
  vcnl4200.setProxHD(false);
  vcnl4200.setProxLEDCurrent(VCNL4200_LED_I_200MA);
  vcnl4200.setProxIntegrationTime(VCNL4200_PS_IT_8T);
}

void loop() {
  // Read the proximity sensor data
  uint16_t proxData = vcnl4200.readProxData();
  Serial.print("Prox Data: ");
  Serial.println(proxData);
  // Read the ambient light sensor (ALS) data
  uint16_t alsData = vcnl4200.readALSdata();
  Serial.print("ALS Data: ");
  Serial.print(alsData);
  // Read the raw white sensor data
  uint16_t whiteData = vcnl4200.readWhiteData();
  Serial.print(", White Data: ");
  Serial.println(whiteData);

  delay(100);
}

Upload the sketch to your board and open up the Serial Monitor (Tools -> Serial Monitor) at 115200 baud. You'll see the VCNL4200 recognized over I2C. Then, proximity, ambient light and white light readings will be printed to the Serial Monitor. You'll see these values changes as you affect your proximity to the sensor and the ambient light around the sensor.

What is WipperSnapper

WipperSnapper is a firmware designed to turn any WiFi-capable board into an Internet-of-Things device without programming a single line of code. WipperSnapper connects to Adafruit IO, a web platform designed (by Adafruit!) to display, respond, and interact with your project's data.

Simply load the WipperSnapper firmware onto your board, add credentials, and plug it into power. Your board will automatically register itself with your Adafruit IO account.

From there, you can add components to your board such as buttons, switches, potentiometers, sensors, and more! Components are dynamically added to hardware, so you can immediately start interacting, logging, and streaming the data your projects produce without writing code.

If you've never used WipperSnapper, click below to read through the quick start guide before continuing.

Wiring

First, wire up an VCNL4200 to your board exactly as follows. Here is an example of the VCNL4200 wired to an Adafruit ESP32 Feather V2 using I2C with a STEMMA QT cable (no soldering required)

Usage

Connect your board to Adafruit IO Wippersnapper and navigate to the WipperSnapper board list.

On this page, select the WipperSnapper board you're using to be brought to the board's interface page.

If you do not see your board listed here - you need to connect your board to Adafruit IO first.

Next, make sure the sensor is plugged into your board and click the I2C Scan button.

You should see the VCNL4200's default I2C address of 0x51 pop-up in the I2C scan list.

With the sensor detected in an I2C scan, you're ready to add the sensor to your board.

Click the New Component button or the + button to bring up the component picker.

Adafruit IO supports a large amount of components. To quickly find your sensor, type VCNL4200 into the search bar, then select the VCNL4200 component.

On the component configuration page, the VCNL4200's sensor address should be listed along with the sensor's settings.

The Send Every option is specific to each sensor's measurements. This option will tell the Feather how often it should read from the VCNL4200 sensor and send the data to Adafruit IO. Measurements can range from every 30 seconds to every 24 hours.

For this example, set the Send Every interval to every 30 seconds.

Your device interface should now show the sensor components you created. After the interval you configured elapses, WipperSnapper will automatically read values from the sensor(s) and send them to Adafruit IO.

To view the data that has been logged from the sensor, click on the graph next to the sensor name.

Here you can see the feed history and edit things about the feed such as the name, privacy, webhooks associated with the feed and more. If you want to learn more about how feeds work, check out this page.

Files

• VCNL4200 Datasheet
• EagleCAD PCB Files on GitHub
• 3D models on GitHub
• Fritzing object in the Adafruit Fritzing Library

Schematic and Fab Print