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89 lines
2.3 KiB
89 lines
2.3 KiB
""" |
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CLI Meter |
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==================================================================== |
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Takes a reading of the light using the meter attached via to the |
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intended Raspberry PI. The reading is the sent to a server where the |
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reading is stored. The intended use for this script is to be run via |
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the command-line without the need for a G.U.I. This should be the |
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version used when the "Return to Ritherdon" project is live. |
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""" |
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import json |
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import RPi.GPIO as GPIO |
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import time, math |
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import requests |
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from datetime import datetime |
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import pdb |
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# Using BCM (Broadcom) names when referencing the GPIO pins. |
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GPIO.setmode(GPIO.BCM) |
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GPIO.setwarnings(True) |
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a_pin = 18 # Charges the capacitor. |
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b_pin = 23 # Discharges the capacitor. |
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api_url = "http://35.176.14.135/api/readings/add/1" |
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def discharge(): |
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GPIO.setup(a_pin, GPIO.IN) |
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GPIO.setup(b_pin, GPIO.OUT) |
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GPIO.output(b_pin, False) |
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time.sleep(0.01) # 0.01 -- initial value |
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def charge_time(): |
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GPIO.setup(b_pin, GPIO.IN) |
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GPIO.setup(a_pin, GPIO.OUT) |
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GPIO.output(a_pin, True) |
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t1 = time.time() |
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while not GPIO.input(b_pin): |
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pass |
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t2 = time.time() |
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return (t2 - t1) * 1000000 |
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def analog_read(): |
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discharge() |
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return charge_time() |
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def read_resistance(): |
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n = 20 |
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total = 0; |
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for i in range(1, n): |
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total = total + analog_read() |
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reading = total / float(n) |
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resistance = reading * 6.05 - 939 |
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return resistance |
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def light_from_r(R): |
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return math.log(1000000.0/R) * 10.0 |
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def get_timestamp(): |
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return datetime.now().strftime(("%Y-%m-%d %H:%M:%S")) |
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def push_reading(lvalue): |
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time = get_timestamp() |
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headers = {"content-type": "application/json"} |
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payload = { "reading": int(lvalue), "time": time} |
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print(payload) |
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res = requests.post(api_url, data=json.dumps(payload), headers=headers) |
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def update_reading(): |
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light = light_from_r(read_resistance()) |
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reading_str = "{:.0f}".format(light) |
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print(reading_str) |
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push_reading(light) |
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def main(): |
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try: |
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while True: |
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#pdb.set_trace() |
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update_reading() |
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except KeyboardInterrupt: |
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print("Keyboard Interrupt: quitting program.") |
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except: |
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print("Error updating light reading...") |
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finally: |
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print("Cleaning up GPIO before closing...") |
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GPIO.cleanup() |
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if __name__ == "__main__": |
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main()
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