Hi,
New to arduino and forum. First project just built. It is a mobile data logger, measuring time and distance to water level (measuring drops for soil infiltration tests in the field)
- Adalogger 32u4
- DS3231 RTC Wing
- Maxbotix XL 7092 Ultrasonic Sensor (cm accuracy)
- 4400mah LiPoly
It idles for 30 seconds to allow positioning after power on. It logs date and time to sd card. It begins taking measurements at approx. 10 second intervals. It is supposed to only log a reading and time in seconds to file if the reading is different to the previous logged value. To reduce the dataset for graphing and calcs.
It is working ok at the moment but is unexpectedly logging same readings in a row intermittently where I thought my code would only log a value if it was different than the previous logged value.
I haven’t got an actual test log at the moment but it goes something like this:
(first value is distance in cm, second value is time in seconds from startup)
31/08/2016 - 15:16
29,1
30,60
31,100
31,125
32,200
33,400
33,420
33,438
34,600
35,850
35,910
35,925
35,1040
35,1055
36,1200
37,1500
#include <SPI.h> //Serial Peripheral Interface Library
#include <Maxbotix.h> //Maxbotix Ultrasonic Sensor Library
#include <SD.h> //SD Card Access Library
#include <RTClib.h> //RTC Access Library
RTC_DS3231 rtc; //Declare RTC as rtc
/*
SENSOR Command Pin 4 is digital pin 6
SENSOR Pin AN is analog pin A1
*/
Maxbotix rangeSensorAD(A1, Maxbotix::AN, Maxbotix::XL); // Initialise Maxbotix Sensor
int waterDistance = 15000; // Declare and set variable waterDistance
long startUnix; // Declare Long integers
long logTime;
File logFile; // Declare file logFile
void setup()
{
#define VBATPIN A9 // Define VBATPIN as Analogue pin 9
float measuredvbat = analogRead(VBATPIN); // Declare and set measuredvbat
rtc.begin(); // Begin the Real Time Clock
DateTime now = rtc.now(); // Set DateTime library source to RTC
Serial.begin(9600); // Begin Serial Communication
SD.begin(4); // Begin SD card Communication
pinMode(A1, INPUT); // Sensor In
pinMode(5, OUTPUT); // Button LED
pinMode(6, OUTPUT); // Sensor Command
pinMode(13, OUTPUT); // Red LED
for (int i = 0; i <= 60; i++) { // Flash Button LED and delay start of operations for approx 30 seconds
digitalWrite(5, HIGH);
delay(250);
digitalWrite(5, LOW);
delay(250);
}
delay(2000);
startUnix = (now.unixtime()) + 32; // Establish start time of operations in unixtime
logFile = SD.open("datalog.txt", FILE_WRITE); // Open log file
delay (500);
logFile.print(now.day(), DEC); // Print date and time to log file
logFile.print('/');
logFile.print(now.month(), DEC);
logFile.print('/');
logFile.print(now.year(), DEC);
logFile.print(" - ");
logFile.print(now.hour(), DEC);
logFile.print(':');
logFile.println(now.minute(), DEC);
logFile.close(); // Close log file
Serial.print(now.day(), DEC); // Print date and time to com
Serial.print('/');
Serial.print(now.month(), DEC);
Serial.print('/');
Serial.print(now.year(), DEC);
Serial.print(" - ");
Serial.print(now.hour(), DEC);
Serial.print(':');
Serial.println(now.minute(), DEC);
delay (500);
}
void loop()
{
float measuredvbat = analogRead(VBATPIN); // Battery voltage check
measuredvbat *= 2; // Convert value to true voltage
measuredvbat *= 3.3;
measuredvbat /= 1024;
if (measuredvbat < 3.6)
{digitalWrite(13, HIGH);} // Light Red LED if battery is low
DateTime now = rtc.now(); // Set DateTime library source to RTC
String dataString = ""; // Declare and empty data string
digitalWrite(5, HIGH); // turn the Button LED on (HIGH is the voltage level)
digitalWrite(6, HIGH); //Turn the sensor on
delay(1000); //Delay 1 second
digitalWrite(5, LOW); // turn the Button LED off (LOW is the voltage level)
digitalWrite(6, LOW); //Turn the sensor off
if ((rangeSensorAD.getRange()) != waterDistance) // If current measured distance is different than previous then print it and change the old value
{
long nowUnix = (now.unixtime()); // Set variable nowUnix to current unixtime
logTime = nowUnix - startUnix; // Calculate seconds since start of logging
Serial.print("AD: "); // Print results to serial monitor
Serial.print(rangeSensorAD.getRange());
Serial.print("cm - Seconds: ");
Serial.print(logTime);
Serial.println();
waterDistance = (rangeSensorAD.getRange()); // Set waterDistance to new value
logFile = SD.open("datalog.txt", FILE_WRITE); // Open log file
delay (1000);
dataString += String(waterDistance); // Create data string
dataString += ",";
dataString += String(logTime);
logFile.println(dataString); // Print data to log file
logFile.close(); // Close log file
delay (1000);
}
delay(8000); // Eight second delay
}
Hoping someone could shed some light on this behaviour. It is probably something really simple that I am missing. Thanks in advance!
I thought that I had to actually send the trigger pin high to get it to take a reading and that it would store the value in a register until I put the trigger pin high again. I thought that calling the library function just read the register. Does that mean my manual trigger pin high line at the start of the loop is unnececessary also?