Created
February 3, 2018 11:28
-
-
Save gcch/f1190c47d13618b01f59ba5387dae8f4 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#!/usr/bin/python | |
#coding: utf-8 | |
# Copy from https://github.com/SWITCHSCIENCE/BME280/blob/master/Python27/bme280_sample.py | |
# Customized by tag | |
import smbus | |
import time | |
import datetime | |
bus_number = 1 | |
i2c_address = 0x76 | |
bus = smbus.SMBus(bus_number) | |
digT = [] | |
digP = [] | |
digH = [] | |
t_fine = 0.0 | |
def writeReg(reg_address, data): | |
bus.write_byte_data(i2c_address, reg_address, data) | |
def setup(): | |
osrs_t = 1 # Temperature oversampling x 1 | |
osrs_p = 1 # Pressure oversampling x 1 | |
osrs_h = 1 # Humidity oversampling x 1 | |
mode = 3 # Normal mode | |
t_sb = 5 # Tstandby 1000ms | |
filter = 0 # Filter off | |
spi3w_en = 0 # 3-wire SPI Disable | |
ctrl_meas_reg = (osrs_t << 5) | (osrs_p << 2) | mode | |
config_reg = (t_sb << 5) | (filter << 2) | spi3w_en | |
ctrl_hum_reg = osrs_h | |
writeReg(0xF2, ctrl_hum_reg) | |
writeReg(0xF4, ctrl_meas_reg) | |
writeReg(0xF5, config_reg) | |
def get_calib_param(): | |
calib = [] | |
for i in range (0x88,0x88+24): | |
calib.append(bus.read_byte_data(i2c_address,i)) | |
calib.append(bus.read_byte_data(i2c_address,0xA1)) | |
for i in range (0xE1,0xE1+7): | |
calib.append(bus.read_byte_data(i2c_address,i)) | |
digT.append((calib[1] << 8) | calib[0]) | |
digT.append((calib[3] << 8) | calib[2]) | |
digT.append((calib[5] << 8) | calib[4]) | |
digP.append((calib[7] << 8) | calib[6]) | |
digP.append((calib[9] << 8) | calib[8]) | |
digP.append((calib[11]<< 8) | calib[10]) | |
digP.append((calib[13]<< 8) | calib[12]) | |
digP.append((calib[15]<< 8) | calib[14]) | |
digP.append((calib[17]<< 8) | calib[16]) | |
digP.append((calib[19]<< 8) | calib[18]) | |
digP.append((calib[21]<< 8) | calib[20]) | |
digP.append((calib[23]<< 8) | calib[22]) | |
digH.append( calib[24] ) | |
digH.append((calib[26]<< 8) | calib[25]) | |
digH.append( calib[27] ) | |
digH.append((calib[28]<< 4) | (0x0F & calib[29])) | |
digH.append((calib[30]<< 4) | ((calib[29] >> 4) & 0x0F)) | |
digH.append( calib[31] ) | |
for i in range(1,2): | |
if digT[i] & 0x8000: | |
digT[i] = (-digT[i] ^ 0xFFFF) + 1 | |
for i in range(1,8): | |
if digP[i] & 0x8000: | |
digP[i] = (-digP[i] ^ 0xFFFF) + 1 | |
for i in range(0,6): | |
if digH[i] & 0x8000: | |
digH[i] = (-digH[i] ^ 0xFFFF) + 1 | |
def compensate_P(adc_P): | |
global t_fine | |
pressure = 0.0 | |
v1 = (t_fine / 2.0) - 64000.0 | |
v2 = (((v1 / 4.0) * (v1 / 4.0)) / 2048) * digP[5] | |
v2 = v2 + ((v1 * digP[4]) * 2.0) | |
v2 = (v2 / 4.0) + (digP[3] * 65536.0) | |
v1 = (((digP[2] * (((v1 / 4.0) * (v1 / 4.0)) / 8192)) / 8) + ((digP[1] * v1) / 2.0)) / 262144 | |
v1 = ((32768 + v1) * digP[0]) / 32768 | |
if v1 == 0: | |
return 0 | |
pressure = ((1048576 - adc_P) - (v2 / 4096)) * 3125 | |
if pressure < 0x80000000: | |
pressure = (pressure * 2.0) / v1 | |
else: | |
pressure = (pressure / v1) * 2 | |
v1 = (digP[8] * (((pressure / 8.0) * (pressure / 8.0)) / 8192.0)) / 4096 | |
v2 = ((pressure / 4.0) * digP[7]) / 8192.0 | |
pressure = pressure + ((v1 + v2 + digP[6]) / 16.0) | |
return pressure/100 | |
def compensate_T(adc_T): | |
global t_fine | |
v1 = (adc_T / 16384.0 - digT[0] / 1024.0) * digT[1] | |
v2 = (adc_T / 131072.0 - digT[0] / 8192.0) * (adc_T / 131072.0 - digT[0] / 8192.0) * digT[2] | |
t_fine = v1 + v2 | |
temperature = t_fine / 5120.0 | |
return temperature | |
def compensate_H(adc_H): | |
global t_fine | |
var_h = t_fine - 76800.0 | |
if var_h != 0: | |
var_h = (adc_H - (digH[3] * 64.0 + digH[4]/16384.0 * var_h)) * (digH[1] / 65536.0 * (1.0 + digH[5] / 67108864.0 * var_h * (1.0 + digH[2] / 67108864.0 * var_h))) | |
else: | |
return 0 | |
var_h = var_h * (1.0 - digH[0] * var_h / 524288.0) | |
if var_h > 100.0: | |
var_h = 100.0 | |
elif var_h < 0.0: | |
var_h = 0.0 | |
return var_h | |
def readData(): | |
data = [] | |
for i in range (0xF7, 0xF7+8): | |
data.append(bus.read_byte_data(i2c_address, i)) | |
pres_raw = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4) | |
temp_raw = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4) | |
hum_raw = (data[6] << 8) | data[7] | |
pres = compensate_P(pres_raw) # hPa | |
temp = compensate_T(temp_raw) # degree Celcius | |
hum = compensate_H(hum_raw) # % | |
return {'temperature':temp, 'pressure':pres, 'humidity':hum} | |
setup() | |
get_calib_param() | |
if __name__ == '__main__': | |
try: | |
data = readData() | |
data['datetime'] = datetime.datetime.now().isoformat() | |
print(data) | |
except KeyboardInterrupt: | |
pass |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment