Improvements to compensated temperature code

[EVA-2020-02-2.git] / examples / compensated-temperature.py

diff --git a/examples/compensated-temperature.py b/examples/compensated-temperature.py
index 64d7a8b9bed07c020f62fd570c011be2d22989cc..b572ad5127eddd247a858cfb805db4d996cae076 100755 (executable)
--- a/examples/compensated-temperature.py
+++ b/examples/compensated-temperature.py
@@ -20,16 +20,24 @@ Press Ctrl+C to exit!
 bus = SMBus(1)
 bme280 = BME280(i2c_dev=bus)
 
+# Get the temperature of the CPU for compensation
 def get_cpu_temperature():
     process = Popen(['vcgencmd', 'measure_temp'], stdout=PIPE)
     output, _error = process.communicate()
     return float(output[output.index('=') + 1:output.rindex("'")])
 
+# Tuning factor for compensation. Decrease this number to adjust the
+# temperature down, and increase to adjust up
 factor = 0.8
 
+cpu_temps = [0] * 5
+
 while True:
     cpu_temp = get_cpu_temperature()
+    # Smooth out with some averaging to decrease jitter
+    cpu_temps = cpu_temps[1:] + [cpu_temp]
+    avg_cpu_temp = sum(cpu_temps) / float(len(cpu_temps))
     raw_temp = bme280.get_temperature()
-    comp_temp = raw_temp - ((cpu_temp - raw_temp) / factor)
+    comp_temp = raw_temp - ((avg_cpu_temp - raw_temp) / factor)
     print("Compensated temperature: {:05.2f} *C".format(comp_temp))
     time.sleep(1.0)