IoT-For-Beginners/6-consumer/lessons/3-spoken-feedback/single-board-computer-set-timer.md

Set a timer - Virtual IoT Hardware and Raspberry Pi

In this part of the lesson, you will call your serverless code to understand the speech, and set a timer n your virtual IoT device or Raspberry Pi based off the results.

Set a timer

The text that comes back from the speech to text call needs to be sent to your serverless code to be processed by LUIS, getting back the number of seconds for the timer. This number of seconds can be used to set a timer.

Timers can be set using the Python threading.Timer class. This class takes a delay time and a function, and after the delay time, the function is executed.

Task - send the text to the serverless function

1. Open the smart-timer project in VS Code, and ensure the virtual environment is loaded in the terminal if you are using a virtual IoT device.

2. Above the process_text function, declare a function called get_timer_time to call the REST endpoint you created:

   def get_timer_time(text):
   

3. Add the following code to this function to define the URL to call:

   url = '<URL>'
   

   Replace <URL> with the URL of your rest endpoint that you built in the last lesson, either on your computer or in the cloud.

4. Add the following code to set the text as a property passed as JSON to the call:

   body = {
       'text': text
   }
   
   response = requests.post(url, json=body)
   

5. Below this, retrieve the seconds from the response payload, returning 0 if the call failed:

   if response.status_code != 200:
       return 0
   
   payload = response.json()
   return payload['seconds']
   

   Successful HTTP calls return a status code in the 200 range, and your serverless code returns 200 if the text was processed and recognized as the set timer intent.

Task - set a timer on a background thread

1. Add the following import statement at the top of the file to import the threading Python library:

   import threading
   

2. Above the process_text function, add a function to speak a response. Fow now this will just write to the console, but later in this lesson this will speak the text.

   def say(text):
       print(text)
   

3. Below this add a function that will be called by a timer to announce that the timer is complete:

   def announce_timer(minutes, seconds):
       announcement = 'Times up on your '
       if minutes > 0:
           announcement += f'{minutes} minute '
       if seconds > 0:
           announcement += f'{seconds} second '
       announcement += 'timer.'
       say(announcement)
   

   This function takes the number of minutes and seconds for the timer, and builds a sentence to say that the timer is complete. It will check the number of minutes and seconds, and only include each time unit if it has a number. For example, if the number of minutes is 0 then only seconds are included in the message. This sentence is then sent to the say function.

4. Below this, add the following create_timer function to create a timer:

   def create_timer(total_seconds):
       minutes, seconds = divmod(total_seconds, 60)
       threading.Timer(total_seconds, announce_timer, args=[minutes, seconds]).start()
   

   This function takes the total number of seconds for the timer that will be sent in the command, and converts this to minutes and seconds. It then creates and starts a timer object using the total number of seconds, passing in the announce_timer function and a list containing the minutes and seconds. When the timer elapses, it will call the announce_timer function, and pass the contents of this list as the parameters - so the first item in the list gets passes as the minutes parameter, and the second item as the seconds parameter.

5. To the end of the create_timer function, add some code to build a message to be spoken to the user to announce that the timer is starting:

   announcement = ''
   if minutes > 0:
       announcement += f'{minutes} minute '
   if seconds > 0:
       announcement += f'{seconds} second '    
   announcement += 'timer started.'
   say(announcement)
   

   Again, this only includes the time unit that has a value. This sentence is then sent to the say function.

6. Add the following to the end of the process_text function to get the time for the timer from the text, then create the timer:

   seconds = get_timer_time(text)
   if seconds > 0:
       create_timer(seconds)
   

   The timer is only created if the number of seconds is greater than 0.

7. Run the app, and ensure the function app is also running. Set some timers, and the output will show the timer being set, and then will show when it elapses:

   pi@raspberrypi:~/smart-timer $ python3 app.py 
   Set a two minute 27 second timer.
   2 minute 27 second timer started.
   Times up on your 2 minute 27 second timer.
   

💁 You can find this code in the code-timer/pi or code-timer/virtual-iot-device folder.

😀 Your timer program was a success!