Phidgets Smart Sprinker Controller with iOS - Part 2

We need to make the following modifications to our iOS app:

• Allow user to view water usage data from the flow meter that has been stored on the Phidget SBC
• Implement a way for users to select which days they would like to water on

Accessing water usage data

Water usage data was stored in a file on the Phidget SBC (more detail below). In order to access the data, the following code was implemented in the viewDidLoad method of our main view controller.

//In ViewController.h
NSMutableArray *volumeArray;
NSMutableArray *dateArray;

//In ViewController.c viewDidLoad method
if(volumeArray == nil){
    volumeArray = [[NSMutableArray alloc] init];
}
if(dateArray == nil){
    dateArray =[[NSMutableArray alloc] init];
}
NSURL *url = [NSURL URLWithString: @"http://sprinklersbc4.local:8080/data/weatherdata.txt"];
NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    formatter.dateFormat = @"EEE MMM dd HH:mm:ss yyyy";
    NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@"\n"];
    NSArray *arr = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] componentsSeparatedByCharactersInSet:set];
    for(int i = 0; i < arr.count; i++){
        if(i % 2 == 0){
            [dateArray addObject:[formatter dateFromString:(NSString *)arr[i]]];
        }
        else{
            [volumeArray addObject:[NSNumber numberWithDouble:[(NSString *)arr[i] doubleValue]]];
        }
    }
    if(volumeArray.count > 0){
        [self graphInit];
        [self updateGraph:volumeArray:dateArray];
        [totalWaterUsage setText:[NSString stringWithFormat:@"Total: %.2f Litres",[[volumeArray valueForKeyPath:@"@sum.self"] doubleValue]]];
    }
}];
[task resume];

After parsing the data we simply have to graph it.

Graphing

For this project, the charts library by Daniel Cohen Gindi was used in order to graph the water usage.

Watering Days

As we can see above, there were a number of key-value pairs added to the dictionary in order to allow the user to configure the watering days. The user can now simply toggle a switch on the iOS app if they want to water on a specific day. The value is stored in NSUserDefaults as before, and then the PhidgetDictionary is modified when the user selects the "Sync to System" button.
The new code for this can be seen below.

-(void)syncSettings:(NSNotification *)notification{
    PhidgetReturnCode result = 0;
    const char *weekdays[] = {"waterSunday","waterMonday","waterTuesday","waterWednesday","waterThursday","waterFriday","waterSaturday"};
    NSString  *duration = [[NSUserDefaults standardUserDefaults] objectForKey:@"duration"];
    NSString  *startHour = [[NSUserDefaults standardUserDefaults] objectForKey:@"startHour"];
    NSString  *startMinute = [[NSUserDefaults standardUserDefaults] objectForKey:@"startMinute"];
    NSString  *isMinutes = [[NSUserDefaults standardUserDefaults] boolForKey:@"isMinutes"] == true ? @"1" : @"0";


    result = PhidgetDictionary_set(ch, "duration", [duration cStringUsingEncoding:NSASCIIStringEncoding]);
    if(result != EPHIDGET_OK){
        [[NSNotificationCenter defaultCenter] postNotificationName:@"syncUnsuccessful" object:nil];
    }
    result = PhidgetDictionary_set(ch, "startHour", [startHour cStringUsingEncoding:NSASCIIStringEncoding]);
    if(result != EPHIDGET_OK){
        [[NSNotificationCenter defaultCenter] postNotificationName:@"syncUnsuccessful" object:nil];
    }
    result = PhidgetDictionary_set(ch, "startMinute", [startMinute cStringUsingEncoding:NSASCIIStringEncoding]);
    if(result != EPHIDGET_OK){
        [[NSNotificationCenter defaultCenter] postNotificationName:@"syncUnsuccessful" object:nil];
    }
    result = PhidgetDictionary_set(ch, "isMinutes", [isMinutes cStringUsingEncoding:NSASCIIStringEncoding]);
    if(result != EPHIDGET_OK){
        [[NSNotificationCenter defaultCenter] postNotificationName:@"syncUnsuccessful" object:nil];
    }
    for(int i = 0; i < 7; i ++){
        NSString *key = [NSString stringWithFormat:@"weekday%dIsEnabled", i];
        NSString *value = [[NSUserDefaults standardUserDefaults] boolForKey:key] == true ? @"1" : @"0";
        result = PhidgetDictionary_set(ch, weekdays[i], [value cStringUsingEncoding:NSASCIIStringEncoding]);
        if(result != EPHIDGET_OK){
            [[NSNotificationCenter defaultCenter] postNotificationName:@"syncUnsuccessful" object:nil];
        }
    }
    
    
    [[NSNotificationCenter defaultCenter] postNotificationName:@"syncSuccessful" object:nil];
}

Program on SBC

The next step is modifying the C code that is running on the Phidget SBC. The following needs to be done:

• Create a PhidgetFrequencyCounter and subscribe to its data events.
• Log data from the Phidget SBC to a file that the iOS app can access.
• Modify existing code so that user can set a duration based on water consumption instead of only time.
• Modify existing code so that lawn is only watered on specific days.

Creating PhidgetFrequencyCounter

In order to easily interface with a flow meter, we will include a PhidgetFrequencyCounter such as the 1054 - Phidget FrequencyCounter or the Versatile Input Phidget into our project. We can subscribe to the PhidgetFrequencyCounter_setOnCountChangeHandler() function which will give us a count change. We can use this count change and the milimeters/pulse value from the flow meter data sheet in order to calcluate the amount of water flowing through the meter.
The code below shows how to create and intialize a PhidgetFrequencyCounter in C.

        
PhidgetFrequencyCounterHandle freq;
...
//Create and init frequency counter
result = PhidgetFrequencyCounter_create(&freq);
if (result != EPHIDGET_OK) {
    PhidgetLog_log(PHIDGET_LOG_ERROR,"failed to create frequency counter\n");
    return 1;
}

result = Phidget_setDeviceSerialNumber((PhidgetHandle)freq, FREQUENCYCOUNTER_SERIAL_NUM);
if (result != EPHIDGET_OK) {
    PhidgetLog_log(PHIDGET_LOG_ERROR,"failed to set frequency counter serial number\n");
    return 1;
}

result = PhidgetFrequencyCounter_setOnCountChangeHandler(freq, onCountChange, NULL);
if(result != EPHIDGET_OK){
    PhidgetLog_log(PHIDGET_LOG_ERROR,"failed to set on count change handler\n");
    return 1;
}    

result = Phidget_openWaitForAttachment((PhidgetHandle)freq, 2000);
if (result != EPHIDGET_OK) {
    PhidgetLog_log(PHIDGET_LOG_ERROR,"Exiting program, frequency counter did not connect\n");
    return 1;
}  

We can use the count change event in order to calculate the total volume of water used. This is shown below:

  
double totalVolume = 0.0;
...
void
onCountChange(PhidgetFrequencyCounterHandle ch, void *ctx, uint64_t counts, double timeChange) {
	totalVolume += (double)counts * 0.00225; //adafruit flow meter specifies 2.25ml per pulse
}

Modifying Main Loop

Now that we are tracking the amount of water being used, we can incorporate this into our main loop. We can also modify the main loop so that the lawn is only watered on user-specified days.

     
//Main loop
while (1) {
    time(&rawtime);
    timeinfo = localtime(&rawtime);

    if (counter++ == 180) { //every 15 minutes (except when watering)
        PhidgetLog_log(PHIDGET_LOG_INFO, "Getting weather information");
        counter = 0;
        updateWeather();
        updateDictionary(dict);
    }

    if (dictionaryUpdate) {
        PhidgetLog_log(PHIDGET_LOG_INFO, "Updating dictionary");
        dictionaryUpdate = 0;
        PhidgetDictionary_get(dict, "startHour", temp, STRING_LENGTH);
        systemSettings.startHour = strtol(temp, NULL, 0);
        PhidgetDictionary_get(dict, "startMinute", temp, STRING_LENGTH);
        systemSettings.startMinute = strtol(temp, NULL, 0);
        PhidgetDictionary_get(dict, "duration", temp, STRING_LENGTH);
        systemSettings.duration = strtol(temp, NULL, 0);
        PhidgetDictionary_get(dict, "isMinutes", temp, STRING_LENGTH);
        systemSettings.isMinutes = strtol(temp, NULL, 0);
        for(i = 0; i < 7; i ++){
            PhidgetDictionary_get(dict, weekdays[i],temp,STRING_LENGTH);
            systemSettings.waterToday[i] = strtol(temp,NULL,0);
        }
    }

    time(&startTime);
    
    if(systemSettings.waterToday[timeinfo->tm_wday]){
        if (timeinfo->tm_hour == systemSettings.startHour && timeinfo->tm_min == systemSettings.startMinute) {
            if(isBadWeather(weather.id) == 0){
            time_t currentTime;
            PhidgetLog_log(PHIDGET_LOG_INFO, "Setting total volume to 0");
            totalVolume = 0;
            PhidgetLog_log(PHIDGET_LOG_INFO, "Water turned on");
            PhidgetDigitalOutput_setState(digout, 1); //turn on water
            do {
                sleep(5);
                time(& currentTime);
            } while(continueWatering(systemSettings, startTime, currentTime));
            PhidgetLog_log(PHIDGET_LOG_INFO, "Water turned off");
            PhidgetLog_log(PHIDGET_LOG_INFO, "Logging total volume used");
            logData();
            PhidgetDigitalOutput_setState(digout, 0); //turn off water
            }
            else{
                PhidgetLog_log(PHIDGET_LOG_INFO, "Bad weather, not going to water");
            }
        }
    }
    else{
        PhidgetLog_log(PHIDGET_LOG_INFO, "Today is not on watering schedule");
    }	

    sleep(5);
}

The code for the continueWatering() function is shown below:

   
int continueWatering(struct IrrigationSettings settings, time_t startTime, time_t currentTime){
    if(settings.isMinutes){
        if(difftime(currentTime,startTime) < (settings.duration * 60.0))
            return 1;
        else
            return 0;
    }
    else{
        if(totalVolume < settings.duration)
            return 1;
        else
            return 0;
    }
}              

Logging Data

As shown in the code above, the logData() function is called after the lawn has been watered for the specified amount of time. This functions simply creates a file and logs the time and amount of water used as shown below:

 
void logData(void) {
    time_t rawtime;
    struct tm * timeinfo;
    time(&rawtime);
    timeinfo = localtime(&rawtime);
    FILE* log = fopen("data/weatherdata.txt", "a");
    if(log == NULL){
    PhidgetLog_log(PHIDGET_LOG_ERROR,"failed to open weatherdata.txt\n");
        return;
    }
    fprintf(log,"\n%s%f", asctime(timeinfo), totalVolume);
    fclose(log);
}

Now that we have stored the data, we should allow our iOS app access to it, so that it can be graphed and shown to users. In order to do that, we must have a Phidget Webserver enabled with access to the file our program will log to.

Now simply create a link to the data/weatherdata.txt file at your docroot location.

As shown above in the iOS code, you can now easily access this file by specifying the URL:
NSURL *url = [NSURL URLWithString: @"http://sprinklersbc4.local:8080/data/weatherdata.txt"];

Conclusion

Upon completion of part 2, we have a sprinkler system that does the following:

• Allows users to enter a specific watering time (e.g. 5:20PM)
• Allows users to enter a specific watering duration. Users can water for X minute or X litres.
• Allows users to specify which days of the week to water
• System checks local weather forecasts and adjusts watering schedule accordingly
• System tracks water usage.

We still have the following goals to accomplish:

1. Allow user to have unique settings for each zone.
2. Make C program smarter. Take future/previous forecasts into account, not just current weather.
3. Improve iOS app look by including themes for different weather forecasts.
4. Installation

Stay tuned for the installation project coming soon!