tested with trinket M0 for CircuitPython

Breath_Tester/Breath_Tester.py

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+import time
+import board
+import busio
+import adafruit_sgp30
+
+i2c = busio.I2C(board.SCL, board.SDA, frequency=100000)
+
+# Create library object on our I2C port
+sgp30 = adafruit_sgp30.Adafruit_SGP30(i2c)
+sgp30.iaq_init()
+sgp30.set_iaq_baseline(0x8973, 0x8aae)
+
+# highest tVOC recorded in 30 seconds
+highest_breath_result = 0
+
+def warmup_message():
+
+    warmup_time = 20 
+    warmup_counter = 0
+
+    co2eq, tvoc = sgp30.iaq_measure()           # initial read required to get sensor going
+
+    print()
+    print("Warming Up [%d seconds]..." % warmup_time)
+
+    while ( warmup_counter <= 20 ):
+        print('.', end='')
+        time.sleep(1)
+        warmup_counter += 1
+
+def get_breath_reading():
+
+    breath_time = 30                            # seconds to record breath reading
+    breath_counter = 0                          # one second count up to breath_time value
+    breath_saves = [0] * ( breath_time + 1 )    # initialize list with empty values
+
+    print()
+    print("We will collect breath samples for 30 seconds.")
+    print("Take a deep breath and exhale into the straw.")
+    input(" *** Press a key when ready. *** ")
+    print()
+
+    while ( breath_counter <= breath_time ):
+        co2eq, tvoc = sgp30.iaq_measure()
+        breath_saves[breath_counter] = tvoc
+        print(tvoc, ', ', end='')
+        time.sleep(1)
+        breath_counter += 1
+
+    breath_saves = sorted(breath_saves)
+    highest_breath_result = breath_saves[breath_counter - 1] 
+
+    return(highest_breath_result)
+
+# show the highest reading recorded
+def show_results(highest_breath_result):
+    print()
+    print()
+    print("peak VOC reading:", highest_breath_result)
+    print()
+    input("Press any key to test again")
+    print()
+
+# main
+while True:
+    warmup_message()
+    highest_breath_result = get_breath_reading()
+    show_results(highest_breath_result)

Breath_Tester/README.md

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+# Breath_Tester
+
+Code to accompany this tutorial:
+https://learn.adafruit.com/breath-tester