Adafruit Trinkey QT2040

published June 23, 2021, last edited January 22, 2025
last major update January 27, 2022

posted in Sensors Adafruit Products CircuitPython STEMMA Raspberry Pi/ RP2040

Beginner

Product guide

Trinkey Arduino Example

Once you have Arduino setup for the Trinkey QT2040, you can run the following demo. This example displays a rainbow on the built-in NeoPixel LED, reads the temperature from an MCP9808 I2C temperature sensor, and reads the BOOT button press and release.

Arduino Library Installation

This example requires you to install two libraries: Adafruit NeoPixel and Adafruit MCP9808.

Open the Arduino Library Manager:

Search for NeoPixel and install Adafruit NeoPixel, being sure to double check the name.

Search for MCP9808 and install Adafruit MCP9808 Library, installing any required dependencies along with it.

QT2040 Trinkey Example

Compile and upload the following example.

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// SPDX-FileCopyrightText: 2021 Kattni Rembor for Adafruit Industries
//
// SPDX-License-Identifier: MIT

/**************************************************************************/
/*!
This is a demo for the Adafruit QT2040 Trinkey and the MCP9808 temperature
sensor.
QT2040 Trinkey - https://www.adafruit.com/product/5056
MCP9808 - https://www.adafruit.com/product/5027

*/
/**************************************************************************/
#include "Adafruit_MCP9808.h"
#include <Adafruit_NeoPixel.h>

// Create the neopixel strip with the built in definitions NUM_NEOPIXEL and
// PIN_NEOPIXEL
Adafruit_NeoPixel pixel =
    Adafruit_NeoPixel(NUM_NEOPIXEL, PIN_NEOPIXEL, NEO_GRB + NEO_KHZ800);

// Create the MCP9808 temperature sensor object
Adafruit_MCP9808 mcp9808 = Adafruit_MCP9808();

long previousMillis = 0;
long intervalTemp = 2000;
bool last_button = false;

void setup() {
  Serial.begin(115200);
  delay(100);

  pinMode(PIN_SWITCH, INPUT_PULLUP); // Setup the BOOT button

  pixel.begin();
  pixel.setBrightness(20);
  pixel.show(); // Initialize all pixels to 'off'

  if (!mcp9808.begin(0x18)) {
    Serial.println("Couldn't find MCP9808! Check your connections and verify "
                   "the address is correct.");
    while (1)
      ;
  }

  mcp9808.setResolution(3);
}

uint8_t j = 0;

void loop() {
  bool curr_button = !digitalRead(PIN_SWITCH);

  pixel.setPixelColor(0, Wheel(j++));
  pixel.show();

  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis > intervalTemp) {
    previousMillis = currentMillis;
    // Read and print out the temperature.
    float c = mcp9808.readTempC();
    float f = mcp9808.readTempF();
    Serial.print("Temp: ");
    Serial.print(c, 4);
    Serial.print("*C\t and ");
    Serial.print(f, 4);
    Serial.println("*F.");
  }

  if (curr_button && !last_button) {
    Serial.println("Button pressed!");
  }
  if (!curr_button && last_button) {
    !Serial.println("Button released!");
  }
  last_button = curr_button;

  delay(10);
}

// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if (WheelPos < 85) {
    return pixel.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if (WheelPos < 170) {
    WheelPos -= 85;
    return pixel.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
    WheelPos -= 170;
    return pixel.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}

// SPDX-FileCopyrightText: 2021 Kattni Rembor for Adafruit Industries
//
// SPDX-License-Identifier: MIT

/**************************************************************************/
/*!
This is a demo for the Adafruit QT2040 Trinkey and the MCP9808 temperature
sensor.
QT2040 Trinkey - https://www.adafruit.com/product/5056
MCP9808 - https://www.adafruit.com/product/5027

*/
/**************************************************************************/
#include "Adafruit_MCP9808.h"
#include <Adafruit_NeoPixel.h>

// Create the neopixel strip with the built in definitions NUM_NEOPIXEL and
// PIN_NEOPIXEL
Adafruit_NeoPixel pixel =
    Adafruit_NeoPixel(NUM_NEOPIXEL, PIN_NEOPIXEL, NEO_GRB + NEO_KHZ800);

// Create the MCP9808 temperature sensor object
Adafruit_MCP9808 mcp9808 = Adafruit_MCP9808();

long previousMillis = 0;
long intervalTemp = 2000;
bool last_button = false;

void setup() {
  Serial.begin(115200);
  delay(100);

  pinMode(PIN_SWITCH, INPUT_PULLUP); // Setup the BOOT button

  pixel.begin();
  pixel.setBrightness(20);
  pixel.show(); // Initialize all pixels to 'off'

  if (!mcp9808.begin(0x18)) {
    Serial.println("Couldn't find MCP9808! Check your connections and verify "
                   "the address is correct.");
    while (1)
      ;
  }

  mcp9808.setResolution(3);
}

uint8_t j = 0;

void loop() {
  bool curr_button = !digitalRead(PIN_SWITCH);

  pixel.setPixelColor(0, Wheel(j++));
  pixel.show();

  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis > intervalTemp) {
    previousMillis = currentMillis;
    // Read and print out the temperature.
    float c = mcp9808.readTempC();
    float f = mcp9808.readTempF();
    Serial.print("Temp: ");
    Serial.print(c, 4);
    Serial.print("*C\t and ");
    Serial.print(f, 4);
    Serial.println("*F.");
  }

  if (curr_button && !last_button) {
    Serial.println("Button pressed!");
  }
  if (!curr_button && last_button) {
    !Serial.println("Button released!");
  }
  last_button = curr_button;

  delay(10);
}

// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if (WheelPos < 85) {
    return pixel.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if (WheelPos < 170) {
    WheelPos -= 85;
    return pixel.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
    WheelPos -= 170;
    return pixel.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}

The NeoPixel will display a rainbow. Open the serial monitor to see the temperature printed out every two seconds. Press the BOOT button to see a message printed on button press and on button release.