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Data Logging to SD Card | NexaLearn IoT Lab | NexaLearn

Data Storage30 دقيقة

Data Logging to SD Card

Collect weather data for your farm for months in an Excel file.

Lesson Content

Data Logging is important in agricultural or industrial projects isolated from the internet. We use an SD Card module (communicating via SPI) and write CSV files that can be read in Excel later. We must be careful not to write data every fraction of a second to avoid filling memory quickly and slowing the system.

Components Needed

Arduino Uno أو ESP32Micro SD Card Module

Wiring Notes

SPI protocol. For Uno: CS(4), MOSI(11), MISO(12), SCK(13).

Code Example

#include <SPI.h>
#include <SD.h>
File dataFile;
void setup() {
  Serial.begin(9600);
  if (!SD.begin(4)) { Serial.println("Failed"); return; }
}
void loop() {
  dataFile = SD.open("data.csv", FILE_WRITE);
  if (dataFile) {
    dataFile.println("12:00, 25.5C");
    dataFile.close();
  }
  delay(60000); // سجل كل دقيقة
}

Common Mistakes

Removing the SD card while Arduino is running, or writing code without closing the file with dataFile.close(), which corrupts the entire file.

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