與前篇文章一樣,SD卡不是感測器,但因是在同一類主題中討論,故列入。

用Mega2560試了SD Datalogger好幾次,今天終於成功,

網路上的討論很多,我列出我是成功的參數:

首先根據註解:

// On the Ethernet Shield, CS is pin 4. Note that even if it's not
// used as the CS pin, the hardware CS pin (10 on most Arduino boards,
// 53 on the Mega) must be left as an output or the SD library
// functions will not work.

也就是說const int chipSelect = 53;  --> For Mega2560

再來根據Sd2PinMap.h中關於Mega2560腳位的定義,

#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
// Mega

// Two Wire (aka I2C) ports
uint8_t const SDA_PIN = 20;
uint8_t const SCL_PIN = 21;

// SPI port
uint8_t const SS_PIN = 53;
uint8_t const MOSI_PIN = 51;
uint8_t const MISO_PIN = 50;
uint8_t const SCK_PIN = 52;

所以基本上依據上述的條件做調整,SD card可以成功的寫入,

不過很奇怪的是,我用Mega2560比UNO在寫入時lost的比較少。

Code:

/*
  SD card datalogger
 
 This example shows how to log data from three analog sensors
 to an SD card using the SD library.
     
 The circuit:
 * analog sensors on analog ins 0, 1, and 2
 * SD card attached to SPI bus as follows:
 * For UNO
 ** MOSI - pin 11
 ** MISO - pin 12
 ** CLK - pin 13
 ** CS - pin 10
 *For Mega2560
 ** MOSI - pin 51
 ** MISO - pin 50
 ** CLK - pin 52
 ** CS - pin 53
 
 
 created  24 Nov 2010
 modified 9 Apr 2012
 by Tom Igoe
 
 This example code is in the public domain.
     
 */

#include <SD.h>

// On the Ethernet Shield, CS is pin 4. Note that even if it's not
// used as the CS pin, the hardware CS pin (10 on most Arduino boards,
// 53 on the Mega) must be left as an output or the SD library
// functions will not work.
const int chipSelect = 53;  

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


  Serial.print("Initializing SD card...");
  // make sure that the default chip select pin is set to
  // output, even if you don't use it:
  pinMode(53, OUTPUT);  //10 for UNO, 53 for Mega2560
 
  // 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:
    return;
  }
  Serial.println("card initialized.");
 
  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  if (SD.exists("datalog.txt")) {
    Serial.println("datalog.txt exists.");
  }
  else {
    Serial.println("datalog.txt doesn't exist.");
  }
 
  // open a new file and immediately close it:
  Serial.println("Creating datalog.txt...");
 
  File dataFile = SD.open("datalog.txt", FILE_WRITE);
}

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 += ",";
    }
  }

  File dataFile = SD.open("datalog.txt", FILE_WRITE);
  //delay(1000);
  // if the file is available, write to it:
  if (dataFile) {
    dataFile.println(dataString);
    dataFile.close();
    // print to the serial port too:
    Serial.println(dataString);
    delay(1000);
  }  
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening datalog.txt");
  }
}

文章標籤
創作者介紹
創作者 fishark 的頭像
fishark

魚的方舟 * 圖形語言的世界* - LabVIEW 工作室 & APP開發研究室 & Arduino整合開發 -

fishark 發表在 痞客邦 留言(0) 人氣()