我尝试使用SD卡构建数据记录器以保存传感器数据。我需要在电路进入休眠状态时立即降低功耗。问题是SD卡模块的功耗约为3mA。我读了很多关于省电的知识,很多人都把电源切换到SD卡模块,并在醒来时重新初始化卡。我无法做到这一点。只要切换SD卡模块,就会抛出错误消息。任何人都可以给我一些提示让我走上正轨吗?如何重新初始化SD卡模块?
由于
1。修改 一切正常,直到第一次醒来。抛出代码错误消息“卡失败或不存在”,循环将重新开始而不写入SD卡。 这是我到目前为止所得到的:
// DHT sensor library
#include "DHT.h"
// SD card library
#include <SD.h>
// for sleep modes
#include <avr/interrupt.h>
#include <avr/power.h>
#include <avr/sleep.h>
#define DHTPIN 9
#define DHTTYPE DHT22 //DHT11, DHT21, DHT22
DHT dht(DHTPIN, DHTTYPE);
// make sure that the default chip select pin is set
const int chipSelect = 4;
int counter = 0;
int sdPower = 8;
volatile int sleepcounter = 0; // count sleep cycles
void setup() {
pinMode(sdPower, OUTPUT);
// output, even if you don't use it to ensure proper SD library working:
pinMode(10, OUTPUT);
digitalWrite(sdPower, LOW);
watchdogOn(); // switch on Watchdog timer
ADCSRA = ADCSRA & B01111111; // switch off ADC, ADEN bit7 zu 0
ACSR = B10000000; // switch off analog Comparator, ACD bit7 to 1
DIDR0 = DIDR0 | B00111111; // switch off digital input buffer, analog input pins 0-5 to 1
dht.begin();
}
// -------------------------------------- LOOP ---------------------------------
void loop() {
Serial.begin(9600);
// ------------------------- initialize SD card -------------------------
digitalWrite(sdPower, HIGH);
Serial.println("Start of recording");
delay(500);
// see if the card is present and can be initialized:
if (!SD.begin(chipSelect)) {
Serial.println("Card failed, or not present");
delay(100);
// don't do anything more:
return;
}
Serial.println("card initialized.");
// --------------------------------------------------------------------------
float humidity = dht.readHumidity(); //measure humidity
float temp = dht.readTemperature(); //measure temp
// make a string for assembling the data to log:
String dataString = "";
// ------------------------- read sensor and store in string -----------------------------
// check for valid number, throw error for NaN (not a number)
if (isnan(temp) || isnan(humidity)) {
Serial.println("no read for DHT22");
}
else {
dataString += "MP-";
dataString += String(counter);
dataString += ",";
dataString += String(temp);
dataString += ",";
dataString += String(humidity);
// ------------------------- open SD card and write values -----------------------------
// open the file. note that only one file can be open at a time,
// so you have to close this one before opening another.
delay(1000);
File dataFile = SD.open("datalog.txt", FILE_WRITE);
// if the file is available, write to it:
if (dataFile) {
dataFile.println(dataString);
dataFile.close(); //dataFile.sync() doesn't change something
delay(500);
// print to the serial port too:
Serial.println(dataString);
delay(500);
counter = counter + 1;
}
// if the file isn't open, pop up an error:
else {
Serial.println("error opening datalog.txt");
}
//-------------------------------------- sleep mode activation ----------------------------
// Stay awake for 0.5 second, then sleep.
delay(500);
digitalWrite(sdPower, LOW);
delay(500);
pwrDown(5); // go to sleep for (x) sec.
}
}
// some methods for sleep mode are not shown
答案 0 :(得分:1)
经常使用的SD.h
库无法管理断电的SD卡模块。断电后代码会抛出错误。该卡无法重新初始化。
我使用SdFat.h
代替它,它的工作非常完美。 SD卡吸引了大量的电流。要切换SD卡模块,建议使用MOSFet。