How to Use Gravity: Serial Data Logger V2.0 for Arduino: Examples, Pinouts, and Specs

The Gravity: Serial Data Logger V2.0 (Manufacturer Part ID: TEL0147) by DFRobot is a compact and efficient data logging module designed specifically for Arduino projects. This module enables users to record and store real-time data from various sensors or devices via serial communication. It supports microSD cards for data storage, making it ideal for applications requiring long-term data collection and analysis.

• Environmental monitoring (e.g., temperature, humidity, air quality)
• IoT data logging for smart devices
• Scientific experiments requiring real-time data collection
• Industrial monitoring and diagnostics
• Educational projects involving data analysis

Below are the key technical details of the Gravity: Serial Data Logger V2.0:

The module has a simple 4-pin interface for easy integration with Arduino boards:

1. Hardware Setup:

   • Connect the VCC pin of the data logger to the 5V or 3.3V pin on the Arduino.
   • Connect the GND pin to the Arduino's ground (GND).
   • Connect the RX pin of the data logger to the TX pin of the Arduino.
   • Connect the TX pin of the data logger to the RX pin of the Arduino.
   • Insert a formatted microSD card (FAT32, up to 32GB) into the module's card slot.

2. Software Setup:

   • Use the Arduino IDE to write and upload a sketch for data logging.
   • Ensure the baud rate in your code matches the module's default (9600 bps) or configured baud rate.

3. Data Logging:

   • Send data to the module via the Arduino's serial interface.
   • The module will automatically write the received data to the microSD card.

• MicroSD Card Formatting: Ensure the microSD card is formatted to FAT32 before use.
• Baud Rate Configuration: If you need to change the baud rate, refer to the manufacturer's documentation for instructions.
• Data Integrity: Avoid removing the microSD card while the module is powered on to prevent data corruption.
• Power Supply: Use a stable power source to ensure reliable operation.
• Serial Communication: Avoid sending data too quickly; allow sufficient time for the module to write data to the microSD card.

Below is an example sketch to log temperature data from a DHT11 sensor to the Gravity: Serial Data Logger V2.0:

#include <DHT.h>

// Define the DHT sensor type and pin
#define DHTPIN 2      // Pin connected to the DHT sensor
#define DHTTYPE DHT11 // DHT 11 sensor

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 bps
  dht.begin();        // Initialize the DHT sensor
  delay(2000);        // Allow the sensor to stabilize
}

void loop() {
  float temperature = dht.readTemperature(); // Read temperature in Celsius
  float humidity = dht.readHumidity();       // Read humidity percentage

  // Check if the readings are valid
  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Format the data as a CSV string
  String data = String(temperature) + "," + String(humidity);

  // Send the data to the Serial Data Logger
  Serial.println(data);

  delay(2000); // Log data every 2 seconds
}

• The code reads temperature and humidity data from a DHT11 sensor.
• The data is formatted as a CSV string (e.g., 25.3,60.2) and sent to the Serial Data Logger via the Arduino's serial interface.
• The logger writes the data to the microSD card for later retrieval.

1. No Data Written to the microSD Card:

   • Ensure the microSD card is properly inserted and formatted to FAT32.
   • Verify the connections between the Arduino and the data logger.
   • Check that the baud rate in your code matches the module's baud rate.

2. Corrupted Data on the microSD Card:

   • Avoid removing the microSD card while the module is powered on.
   • Use a high-quality microSD card to minimize errors.

3. Module Not Responding:

   • Confirm that the power supply voltage is within the specified range (3.3V - 5V).
   • Double-check the RX and TX connections between the Arduino and the module.

4. Data Logging Too Slow:

   • Reduce the frequency of data transmission in your code.
   • Use a faster microSD card with a higher class rating (e.g., Class 10).

Q1: Can I use this module with microcontrollers other than Arduino?
A1: Yes, the module can be used with any microcontroller that supports UART communication, such as ESP32, Raspberry Pi (via USB-to-UART), or STM32.

Q2: How do I change the baud rate of the module?
A2: Refer to the manufacturer's documentation for instructions on changing the baud rate using specific serial commands.

Q3: What happens if the microSD card is full?
A3: The module will stop writing data once the microSD card is full. Regularly check and clear the card to ensure continuous operation.

Q4: Can I log binary data instead of text?
A4: Yes, the module supports logging binary data. Ensure your microcontroller sends the data in the desired format.

By following this documentation, you can effectively integrate the Gravity: Serial Data Logger V2.0 into your projects for reliable and efficient data logging.