Light Intensity

During the loop execution of this example code, ambient light intensity is displayed on the screen and recorded, at two distinct sampling periods. A cell phone flahslight was swept in front of the sensor, producing the results below.

""" lightintensity.py

Use the color sensor to record ambient light intensity.

Setup:
    Connect color sensor to port number 1.

"""
# Importing modules and classes
import time
import numpy as np
from pyev3.utils import plot_line
from pyev3.brick import LegoEV3
from pyev3.devices import Color

# Defining parameters
tstop = 5 # Execution loop duration (s)
tsample = 0.02 # Data sampling period (s)
tdisp = 0.2 # Screen display period (s)

# Pre-allocating output arrays
t = []
ambint = []

# Creating LEGO EV3 objects
ev3 = LegoEV3()
color = Color(ev3, portnum=1, inputmode='ambient')

# Initializing current time stamp and starting clock
tprev = 0
tcurr = 0
tstart = time.perf_counter()
# Changing EV3 status light
ev3.set_statuslight(mode='pulsing')
# Running execution loop
ambprev = color.output
print('Running for', tstop, 'seconds ...')
while tcurr <= tstop:
    # Getting current ambient light intensity
    ambcurr = color.output
    # Updating previous time and getting current time (s)
    tprev = tcurr
    tcurr = time.perf_counter() - tstart
    # Displaying light intensity every `tdisp` seconds
    if (np.floor(tcurr/tdisp) - np.floor(tprev/tdisp)) == 1:
        print('Intensity = ', ambcurr)
        ambprev = ambcurr
    # Acquiring data every `tsample` seconds
    # and appending values to output arrays
    if (np.floor(tcurr/tsample) - np.floor(tprev/tsample)) == 1:
        t.append(tcurr)
        ambint.append(ambcurr)
print('Done.')
# Closing brick connection
ev3.set_statuslight(mode='solid')
ev3.close()

# Plotting results
plot_line([t], [ambint], yname=['Ambient Light Int. (%)'], marker=True)