cs=1,
dc=9,
backlight=12,
- #rotation=270,
- rotation=90,
+ rotation=270,
+ #rotation=90, # flip upside down wrt enviro+ default orientation
spi_speed_hz=10000000
)
# Displays data and text on the 0.96" LCD
def display_text2(variable, data, unit, values):
# Scale the values for the variable between 0 and 1
- print('DEBUG:len(values[' + str(variable) + ']):' + str(len(values[variable])))
+ #print('DEBUG:len(values[' + str(variable) + ']):' + str(len(values[variable])))
#print('DEBUG:values[' + str(variable) + ']:' + str(values[variable]))
vmin = min(values[variable])
vmax = max(values[variable])
output, _error = process.communicate()
return float(output[output.index('=') + 1:output.rindex("'")])
+def rel_to_abs(T,P,RH):
+ """Returns absolute humidity given relative humidity.
+
+ Inputs:
+ --------
+ T : float
+ Absolute temperature in units Kelvin (K).
+ P : float
+ Total pressure in units Pascals (Pa).
+ RH : float
+ Relative humidity in units percent (%).
+
+ Output:
+ --------
+ absolute_humidity : float
+ Absolute humidity in units [kg water vapor / kg dry air].
+
+ References:
+ --------
+ 1. Sonntag, D. "Advancements in the field of hygrometry". 1994. https://doi.org/10.1127/metz/3/1994/51
+ 2. Green, D. "Perry's Chemical Engineers' Handbook" (8th Edition). Page "12-4". McGraw-Hill Professional Publishing. 2007.
+
+ Version: 0.0.1
+ Author: Steven Baltakatei Sandoval
+ License: GPLv3+
+ """
+
+ import math;
+
+ # Check input types
+ T = float(T);
+ P = float(P);
+ RH = float(RH);
+
+ #debug
+ # print('DEBUG:Input Temperature (K) :' + str(T));
+ # print('DEBUG:Input Pressure (Pa) :' + str(P));
+ # print('DEBUG:Input Rel. Humidity (%) :' + str(RH));
+
+ # Set constants and initial conversions
+ epsilon = 0.62198 # (molar mass of water vapor) / (molar mass of dry air)
+ t = T - 273.15; # Celsius from Kelvin
+ P_hpa = P / 100; # hectoPascals (hPa) from Pascals (Pa)
+
+ # Calculate e_w(T), saturation vapor pressure of water in a pure phase, in Pascals
+ ln_e_w = -6096*T**-1 + 21.2409642 - 2.711193*10**-2*T + 1.673952*10**-5*T**2 + 2.433502*math.log(T); # Sonntag-1994 eq 7; e_w in Pascals
+ e_w = math.exp(ln_e_w);
+ e_w_hpa = e_w / 100; # also save e_w in hectoPascals (hPa)
+ # print('DEBUG:ln_e_w:' + str(ln_e_w)); # debug
+ # print('DEBUG:e_w:' + str(e_w)); # debug
+
+ # Calculate f_w(P,T), enhancement factor for water
+ f_w = 1 + (10**-4*e_w_hpa)/(273 + t)*(((38 + 173*math.exp(-t/43))*(1 - (e_w_hpa / P_hpa))) + ((6.39 + 4.28*math.exp(-t / 107))*((P_hpa / e_w_hpa) - 1))); # Sonntag-1994 eq 22.
+ # print('DEBUG:f_w:' + str(f_w)); # debug
+
+ # Calculate e_prime_w(P,T), saturation vapor pressure of water in air-water mixture, in Pascals
+ e_prime_w = f_w * e_w; # Sonntag-1994 eq 18
+ # print('DEBUG:e_prime_w:' + str(e_prime_w)); # debug
+
+ # Calculate e_prime, vapor pressure of water in air, in Pascals
+ e_prime = (RH / 100) * e_prime_w;
+ # print('DEBUG:e_prime:' + str(e_prime)); # debug
+
+ # Calculate r, the absolute humidity, in [kg water vapor / kg dry air]
+ r = (epsilon * e_prime) / (P - e_prime);
+ # print('DEBUG:r:' + str(r)); # debug
+
+ return float(r);
+
# Tuning factor for compensation. Decrease this number to adjust the
# temperature down, and increase to adjust up
variables = ["temperature",
"pressure",
"humidity",
+ "humidity_abs",
"light"]
values = {} # Initialize values dictionary
for v in variables:
# now_temp_tuple (°C)
# now_pressure_tuple (hPa)
# now_humidity_tuple (%)
+ # now_humidity_abs_gkg_tuple (g water vapor / kg dry air)
# now_illuminance_tuple (lux)
- # Depends: time, bme280, ltr559, get_cpu_temperature()
+ # Depends: time, bme280, ltr559, get_cpu_temperature(), rel_to_abs()
# Tell function to modify these global variables
global now_temp_tuple
global now_pressure_tuple
global now_humidity_tuple
+ global now_humidity_abs_gkg_tuple
global now_illuminance_tuple
# Initialize
cpu_temps = []
now_time_ns = time.time_ns() # Get time reading (unix epoch, nanoseconds)
now_pressure = bme280.get_pressure() # get hPa from BME280 sensor
now_pressure_tuple = (time.time_ns(), 'hPa', now_pressure)
- # Get humidity reading
- now_humidity = bme280.get_humidity() # get % humidity from BME280 sensor
+ # Get relative humidity reading
+ now_humidity = bme280.get_humidity() # get % relative humidity from BME280 sensor
now_humidity_tuple = (time.time_ns(), '%', now_humidity)
+ # Calculate absolute humidity reading
+ raw_temp_k = 273.15 + raw_temp; # convert sensor temp from degC to K
+ now_pressure_pa = now_pressure * 100; # convert sensor pressure from hPa to Pa
+ now_humidity_abs = rel_to_abs(raw_temp_k, now_pressure_pa, now_humidity); # calc kg/kg abs humidity
+ now_humidity_abs_gkg = now_humidity_abs * 1000;
+ now_humidity_abs_gkg_tuple = (time.time_ns(), 'g/kg', now_humidity_abs_gkg);
# Get light reading
proximity = ltr559.get_proximity() # get proximity reading
if proximity < 10:
global now_temp_tuple
global now_pressure_tuple
global now_humidity_tuple
+ global now_humidity_abs_gkg_tuple
global now_illuminance_tuple
global varLenBuffer
global fixLenBuffer
#print('DEBUG:now_temp_tuple:' + str(now_temp_tuple))
#print('DEBUG:now_pressure_tuple:' + str(now_pressure_tuple))
#print('DEBUG:now_humidity_tuple:' + str(now_humidity_tuple))
+ #print('DEBUG:now_humidity_abs_gkg_tuple:' + str(now_humidity_abs_gkg_tuple))
#print('DEBUG:now_illuminance_tuple:' + str(now_illuminance_tuple))
# Append new sensor tuples to varying-length buffer
varLenBuffer[variables[0]].append(now_temp_tuple)
## Pressure
varLenBuffer[variables[1]].append(now_pressure_tuple)
- ## Humidity
+ ## Relative Humidity
varLenBuffer[variables[2]].append(now_humidity_tuple)
+ ## Absolute Humidity
+ varLenBuffer[variables[3]].append(now_humidity_abs_gkg_tuple)
## Illuminance
- varLenBuffer[variables[3]].append(now_illuminance_tuple)
+ varLenBuffer[variables[4]].append(now_illuminance_tuple)
#print('DEBUG:varLenBuffer:' + str(varLenBuffer))
# Trim outdated sensor tuples from varying-length buffer
data = bme280.get_humidity()
#display_text(variables[mode], data, unit)
display_text2(variables[mode],data,unit,fixLenBuffer)
-
+
if mode == 3:
+ # variable = "humidity_abs"
+ unit = "g/kg"
+ raw_temp = bme280.get_temperature() # get °C from BME280 sensor
+ raw_temp_k = 273.15 + raw_temp; # convert sensor temp from degC to K
+ now_pressure = bme280.get_pressure() # get hPa from BME280 sensor
+ now_pressure_pa = now_pressure * 100; # convert sensor pressure from hPa to Pa
+ now_humidity = bme280.get_humidity() # get % relative humidity from BME280 sensor
+ now_humidity_abs = rel_to_abs(raw_temp_k,now_pressure_pa,now_humidity); # calc [kg water / kg dry air] abs humidity
+ now_humidity_abs_gkg = now_humidity_abs * 1000; # convert kg/kg to g/kg abs humidity
+ data = now_humidity_abs_gkg;
+ # print('DEBUG:raw_temp:' + str(raw_temp));
+ # print('DEBUG:raw_temp_k:' + str(raw_temp_k));
+ # print('DEBUG:now_pressure:' + str(now_pressure));
+ # print('DEBUG:now_pressure_pa:' + str(now_pressure_pa));
+ # print('DEBUG:now_humidity:' + str(now_humidity));
+ # print('DEBUG:now_humidity_abs_gkg:' + str(data));
+ display_text2(variables[mode],data,unit,fixLenBuffer)
+
+ if mode == 4:
# variable = "light"
unit = "Lux"
if proximity < 10:
projects / EVA-2020-02-2.git / blobdiff