Nano 33 IOT, Multiple DS18B20 Sensors, Micro SD Card Module

Projects Discussion and Showcase Science and Measurement
1

I have the Nano 33 IOT, Multiple DS18B20 temp sensors (addresses recorded), and a Micro SD card module. Everything is wired correctly, I know from testing.

I can read and display the sensor data from the DS18B20's onto the serial monitor no problem. I can even use the example code to read / write and verify the data onto the Micro SD card. My only issue is writing the temp data to the card. I'd love to use the internal RTC to include a time stamp on each data entry. I would like to read the temp sensors once per minute. The file should probably be a CSV to use Excel spreadsheets or something similar.

I have looked all over on how to put the data onto the SD card but I'm not seeing anything that works like I have setup. I want to use the temp sensors address in the code.

At some point I would love to include sensor readings from the onboard 6DOF sensor and an added GPS sensor at some point. I really just want to focus on the temp sensors writing onto the SD card.

How do I tell it how to separate the columns and whatnot?

Please let me know if you need any additional info on this project. I really appreciate any and all help I may get.

2

CSV means
Comma seperated variable
So seperate your variables with commas.

There is a data logging example included with the SD library.

3

I should have known on the CSV thing.

I've been trying to modify the datalogging example to work with my needs. with no luck.

4

Your code is a state secret then, is it?

5

The code I'm currently working on is pasted below. It's what I got done so far in the little free time I have had. I took the datalogger example and started adding the multi temp sensor code i tested to work. I'm not sure where to go next.

#include <SPI.h>
#include <SD.h>
#include <OneWire.h>
#include <DallasTemperature.h>

const int chipSelect = 10;

// Data wire is plugged into port 4 on the Arduino
#define ONE_WIRE_BUS 4

// Setup a oneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);

// Pass our oneWire reference to Dallas Temperature.
DallasTemperature sensors(&oneWire);

// Addresses of 3 DS18B20s
uint8_t InsideBoxTemp[8] = { 0x28, 0x11, 0x60, 0xf3, 0x58, 0x20, 0x01, 0x5b };
uint8_t OutsideBoxTemp[8] = { 0x28, 0x3e, 0x8c, 0x78, 0x58, 0x20, 0x01, 0x7f };

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  sensors.begin();
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


  Serial.print("Initializing SD card...");

  // see if the card is present and can be initialized:
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    while (1);
  }
  Serial.println("card initialized.");
}

void loop() {
  // make a string for assembling the data to log:
  String dataString = "";

  // read three sensors and append to the string:
  for (int analogPin = 0; analogPin < 3; analogPin++) {
    int sensor = analogRead(analogPin);
    dataString += String(sensor);
    if (analogPin < 2) {
      dataString += ",";
    }
  }

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  File dataFile = SD.open("Temp01.txt", FILE_WRITE);

  // if the file is available, write to it:
  if (dataFile) {
    dataFile.println(dataString);
    dataFile.close();
    // print to the serial port too:
    Serial.println(dataString);
  }
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening Temp01.txt");
  }
}
6

I think your temperature code is rubbish, so go to one that works.
"Arduino 1-Wire Tutorial" Arduino 1-Wire Tutorial
Opening and closing the file in the loop is a bad idea, but not immediately fatal. Open once in setup.

7

My temperature code works perfectly fine, thanks!

Ok...

8

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