Arduino Loop and alarm - arduino

Question

I'm working on my first physical computing project with an arduino, well actually a seeduino stalker 2.1. I'm building a device to record water collection rates over time.
Getting the project set up and running hasn't been all that hard, until today that is. Inside the main loop I have a call to the a method that handles the logging. I also now an alarm delay to handle a timer repeat I need in order to summarize data and send it via SMS to a recipient number.
The issue is that when the alarm.repeat() is active it preempts the logging of the data. The question is: why is the logging method inside the loop not working when the alarm.delay is there?
void setup() {
Serial.begin(9600);
Wire.begin();
setTime(1,17,0,1,1,13); // set time
Alarm.timerRepeat(60, Repeats); //set repeater
}
void loop(){
logging(); //call logging
Alarm.delay(1300); //for repeater
}
void Repeats(){
Serial.println("the repeater fired"); // just to see it working
}
void logging(){
val = digitalRead(Sensor_Pin); // read Sensor_Pin
if (val == HIGH) {
// If Sensor N.C. (no with magnet) -> HIGH : Switch is open / LOW : Switch is closed
// If Sensor N.0. (nc with magnet) -> HIGH : Switch is closed / LOW : Switch is open
digitalWrite(Led_Pin, LOW); //Set Led low
//Serial.print("status -->");
//Serial.println("low");
//delay(500);
} else {
digitalWrite(Led_Pin, HIGH); //Set Led high
logdata();
}
}
void logdata(){
// 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 myFile = SD.open("datalog.txt", FILE_WRITE);
// if the file opened okay, write to it:
if (myFile) {
//DateTime now = RTC.now();
//String myString = readTimestamp(now);
time_t t = now();
String aDate = String(year(t))+"/"+String(month(t))+"/"+String(day(t))+" "+String(hour(t))+":"+String(minute(t))+":"+String(second(t));
myFile.println(aDate);
// close the file:
myFile.close();
Serial.println(aDate);
delay(500); } else {
// if the file didn't open, print an error:
// Serial.println("error opening DATALOG.TXT");
}
}

Answer 1

Q: Why must I use Alarm.delay() instead of delay()? A: Task scheduling
is handled in the Alarm.delay function. Tasks are monitored and
triggered from within the Alarm.delay call so Alarm.delay should be
called whenever a delay is required in your sketch. If your sketch
waits on an external event (for example, a sensor change), make sure
you repeatedly call Alarm.delay while checking the sensor.
From the FAQ of the Alarm library. So it looks like Alarm.Delay is just like the standard delay but can be interrupted by scheduled events. Your logging call isn't scheduled, it just happens at the start of the loop. ..is your logging not happening at all? It looks like it should be called at the start of each loop, then a 1300 delay with your repeater firing during the delay.

Answer 2

On your logdata() function you're calling delay(50) instead of Alarm.delay(50).
As caude pointed, you have to use Alarm.delay when a delay is needed, otherwise the delay will mess up with the alarms.

Answer 3

I think you could have done in other way using timer library. If you say the data has to be logged every second,it easier to done by timer.Example code
#include <SimpleTimer.h>
// the timer object
SimpleTimer timer;
// a function to be executed periodically
void repeatMe() {
Serial.print("Uptime (s): ");
Serial.println(millis() / 1000);
}
void setup() {
Serial.begin(9600);
timer.setInterval(1000, repeatMe);
}
void loop() {
timer.run();
}