1  # SPDX-FileCopyrightText: 2018 Mikey Sklar for Adafruit Industries
 2  #
 3  # SPDX-License-Identifier: MIT
 4  
 5  import time
 6  
 7  import adafruit_sgp30
 8  import board
 9  import busio
10  
11  i2c = busio.I2C(board.SCL, board.SDA, frequency=100000)
12  
13  # Create library object on our I2C port
14  sgp30 = adafruit_sgp30.Adafruit_SGP30(i2c)
15  sgp30.iaq_init()
16  sgp30.set_iaq_baseline(0x8973, 0x8aae)
17  
18  # highest tVOC recorded in 30 seconds
19  highest_breath_result = 0
20  
21  
22  def warmup_message():
23      warmup_time = 20
24      warmup_counter = 0
25  
26      # initial read required to get sensor going
27      sgp30.iaq_measure()
28  
29      print()
30      print("Warming Up [%d seconds]..." % warmup_time)
31  
32      while warmup_counter <= 20:
33          print('.', end='')
34          time.sleep(1)
35          warmup_counter += 1
36  
37  
38  def get_breath_reading():
39      breath_time = 30  # seconds to record breath reading
40      # one second count up to breath_time value
41      breath_counter = 0
42      # initialize list with empty values
43      breath_saves = [0] * (breath_time + 1)
44  
45      print()
46      print("We will collect breath samples for 30 seconds.")
47      print("Take a deep breath and exhale into the straw.")
48      input(" *** Press a key when ready. *** ")
49      print()
50  
51      while breath_counter <= breath_time:
52          _, tvoc = sgp30.iaq_measure()
53          breath_saves[breath_counter] = tvoc
54          print(tvoc, ', ', end='')
55          time.sleep(1)
56          breath_counter += 1
57  
58      breath_saves = sorted(breath_saves)
59      result = breath_saves[breath_counter - 1]
60  
61      return result
62  
63  
64  # show the highest reading recorded
65  
66  
67  def show_results(breath_result):
68      print()
69      print()
70      print("peak VOC reading:", breath_result)
71      print()
72      input("Press any key to test again")
73      print()
74  
75  
76  # main
77  while True:
78      warmup_message()
79      highest_breath_result = get_breath_reading()
80      show_results(highest_breath_result)