How to Use Qwiic Shield (Thing Plus): Examples, Pinouts, and Specs

The Qwiic Shield (Thing Plus) by SparkFun is a versatile add-on board designed to expand the functionality of the Thing Plus microcontroller. It features multiple Qwiic connectors, enabling seamless integration of I2C sensors and devices. The Qwiic system eliminates the need for soldering, making it ideal for rapid prototyping and development. This shield is perfect for projects requiring multiple I2C devices, such as environmental monitoring, robotics, and IoT applications.

• Rapid prototyping with I2C sensors and modules
• IoT projects requiring multiple sensor inputs
• Robotics and automation systems
• Environmental monitoring and data logging
• Educational projects for learning I2C communication

The Qwiic Shield (Thing Plus) is designed to simplify I2C communication and provide a reliable interface for connecting multiple Qwiic-enabled devices. Below are its key technical details:

• Input Voltage: 3.3V (from the Thing Plus microcontroller)
• I2C Interface: Supports up to 127 devices on a single bus
• Connectors: 4x Qwiic connectors (standard 4-pin JST)
• Dimensions: 2.2" x 0.9" (55.88mm x 22.86mm)
• Compatibility: Designed for SparkFun Thing Plus microcontrollers
• Mounting: Standard Thing Plus form factor with castellated edges

The Qwiic Shield (Thing Plus) has a simple pinout that aligns with the Thing Plus microcontroller. Below is a table describing the key pins and their functions:

The shield also features four Qwiic connectors, which are internally connected to the SDA and SCL lines, allowing multiple I2C devices to be daisy-chained.

The Qwiic Shield (Thing Plus) is designed for ease of use, especially for those working with I2C devices. Follow the steps below to get started:

1. Attach the Shield: Align the Qwiic Shield with the Thing Plus microcontroller and solder it in place or use headers for a removable connection.
2. Connect Qwiic Devices: Plug your Qwiic-enabled sensors or modules into any of the four Qwiic connectors on the shield.
3. Power the System: Supply power to the Thing Plus microcontroller (via USB or external power source). The shield will draw power from the microcontroller.
4. Write Your Code: Use the Arduino IDE or your preferred development environment to write code for communicating with the connected I2C devices.

• I2C Address Conflicts: Ensure that each connected I2C device has a unique address. If two devices share the same address, use an I2C multiplexer or modify the device's address (if supported).
• Cable Length: Keep Qwiic cable lengths as short as possible to avoid signal degradation, especially when using multiple devices.
• Power Requirements: Verify that the total current draw of all connected devices does not exceed the Thing Plus microcontroller's power output.

Below is an example of how to use the Qwiic Shield with an I2C temperature sensor (e.g., SparkFun Qwiic TMP102):

#include <Wire.h>
#include <SparkFun_TMP102.h> // Include the TMP102 library

TMP102 tempSensor; // Create an instance of the TMP102 class

void setup() {
  Wire.begin(); // Initialize I2C communication
  Serial.begin(9600); // Start serial communication for debugging

  if (!tempSensor.begin()) {
    Serial.println("TMP102 not detected. Check connections."); 
    while (1); // Halt the program if the sensor is not found
  }

  Serial.println("TMP102 detected. Starting temperature readings...");
}

void loop() {
  float temperature = tempSensor.readTempC(); // Read temperature in Celsius
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");

  delay(1000); // Wait 1 second before the next reading
}

• The SparkFun_TMP102.h library must be installed in the Arduino IDE. You can install it via the Library Manager.
• Ensure the TMP102 sensor is connected to one of the Qwiic connectors on the shield.

1. Qwiic Device Not Detected

   • Cause: Incorrect wiring or loose connections.
   • Solution: Verify that the Qwiic cables are securely connected and that the shield is properly attached to the Thing Plus.

2. I2C Address Conflict

   • Cause: Two devices on the same bus share the same I2C address.
   • Solution: Check the datasheets of the connected devices and ensure each has a unique address. Use an I2C scanner sketch to identify conflicts.

3. No Power to Devices

   • Cause: Insufficient power supply or incorrect connections.
   • Solution: Ensure the Thing Plus microcontroller is powered and that the shield is properly connected.

4. Unstable Readings

   • Cause: Long Qwiic cables or electrical noise.
   • Solution: Use shorter cables and ensure a clean power supply.

Q: Can I use the Qwiic Shield with microcontrollers other than the Thing Plus?
A: The shield is specifically designed for the Thing Plus form factor. However, with proper wiring, it can be adapted for use with other 3.3V microcontrollers.

Q: How many Qwiic devices can I connect to the shield?
A: The I2C bus supports up to 127 devices, but practical limitations depend on power availability and signal integrity.

Q: Do I need to solder the shield to the Thing Plus?
A: Soldering is recommended for a permanent connection, but you can use headers for a removable setup.

Q: Can I use 5V I2C devices with this shield?
A: No, the Qwiic system operates at 3.3V. Using 5V devices may damage the shield or connected components. Use a logic level shifter if 5V devices are required.

This concludes the documentation for the Qwiic Shield (Thing Plus). For further assistance, refer to SparkFun's official resources or community forums.