Responding to HTTP Events with Physical Results

Previously we have blinked LED lights when events have taken place, but what about if we could raise a flag, wave, or some other physical action based on these IoT events?

This is where using an ESP8266 rather than a "land locked" microcontroller helps us. We can poll an online API, and detect the state that we want, then drive motors and servos in response!

We can repurpose the Circuit Playground servo code for the physical part, driving the servos through the Crickit Featherwing:

import time
import board
from busio import I2C
from adafruit_seesaw.seesaw import Seesaw
from adafruit_seesaw.pwmout import PWMOut
from adafruit_motor import servo


i2c = I2C(board.SCL, board.SDA)
seesaw = Seesaw(i2c)

# servo object
pwm = PWMOut(seesaw, 17)
pwm.frequency = 50
my_servo = servo.Servo(pwm)

for i in range(0, 3):
    my_servo.angle = 0
    time.sleep(1)
    my_servo.angle = 45
    time.sleep(1)
    my_servo.angle = 135
    time.sleep(1)
    my_servo.angle = 180
    time.sleep(1)

There is an existing API for checking the @Utopian-IO votes, but unfortunately, it returns too many. We only want the current vote.

To get around this I created an intermediate script on my dev server, with the added benefit it made testing easy (it could be weeks until I get a Utopian vote!).

For this we simply utilize urequests which is a micropython version of the Python 3 requests module.

Adafruit supply example code for HTTP gets, but there are a few issues:

1. It's not the "python" way, one of the benefits of Micro and Circuit Python is being able to use familiar syntax
2. Their example code is for http (port 80), and does not handle redirects
3. We want the output as JSON

As you can see, using the request result as JSON affords us the ability to just extract the author, with no processing on our side!

The final part is to execute our earlier servo script. I use exec so I can keep modifying it independently.

from time import sleep
import urequests

while 1:
    response = urequests.get("https://steemitbots.com/api/utopian.py")
    data = response.json()

    try:
        author = data['author']
        print(author)
    except:
        print("oops")

    if author == "makerhacks":
        exec(open("servos.py").read())

    sleep(60)

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