your board may have the newer pressure sensor, BMP388.
Try this code
#!/usr/bin/python
# -*- coding: utf-8 -*-
import time
import smbus
import math
# define BMP388 Device I2C address
I2C_ADD_BMP388_AD0_LOW = 0x76
I2C_ADD_BMP388_AD0_HIGH = 0x77
I2C_ADD_BMP388 = I2C_ADD_BMP388_AD0_HIGH
BMP388_REG_ADD_WIA = 0x00
BMP388_REG_VAL_WIA = 0x50
BMP388_REG_ADD_ERR = 0x02
BMP388_REG_VAL_FATAL_ERR = 0x01
BMP388_REG_VAL_CMD_ERR = 0x02
BMP388_REG_VAL_CONF_ERR = 0x04
BMP388_REG_ADD_STATUS = 0x03
BMP388_REG_VAL_CMD_RDY = 0x10
BMP388_REG_VAL_DRDY_PRESS = 0x20
BMP388_REG_VAL_DRDY_TEMP = 0x40
BMP388_REG_ADD_CMD = 0x7E
BMP388_REG_VAL_EXTMODE_EN = 0x34
BMP388_REG_VAL_FIFI_FLUSH = 0xB0
BMP388_REG_VAL_SOFT_RESET = 0xB6
BMP388_REG_ADD_PWR_CTRL = 0x1B
BMP388_REG_VAL_PRESS_EN = 0x01
BMP388_REG_VAL_TEMP_EN = 0x02
BMP388_REG_VAL_NORMAL_MODE = 0x30
BMP388_REG_ADD_PRESS_XLSB = 0x04
BMP388_REG_ADD_PRESS_LSB = 0x05
BMP388_REG_ADD_PRESS_MSB = 0x06
BMP388_REG_ADD_TEMP_XLSB = 0x07
BMP388_REG_ADD_TEMP_LSB = 0x08
BMP388_REG_ADD_TEMP_MSB = 0x09
BMP388_REG_ADD_T1_LSB = 0x31
BMP388_REG_ADD_T1_MSB = 0x32
BMP388_REG_ADD_T2_LSB = 0x33
BMP388_REG_ADD_T2_MSB = 0x34
BMP388_REG_ADD_T3 = 0x35
BMP388_REG_ADD_P1_LSB = 0x36
BMP388_REG_ADD_P1_MSB = 0x37
BMP388_REG_ADD_P2_LSB = 0x38
BMP388_REG_ADD_P2_MSB = 0x39
BMP388_REG_ADD_P3 = 0x3A
BMP388_REG_ADD_P4 = 0x3B
BMP388_REG_ADD_P5_LSB = 0x3C
BMP388_REG_ADD_P5_MSB = 0x3D
BMP388_REG_ADD_P6_LSB = 0x3E
BMP388_REG_ADD_P6_MSB = 0x3F
BMP388_REG_ADD_P7 = 0x40
BMP388_REG_ADD_P8 = 0x41
BMP388_REG_ADD_P9_LSB = 0x42
BMP388_REG_ADD_P9_MSB = 0x43
BMP388_REG_ADD_P10 = 0x44
BMP388_REG_ADD_P11 = 0x45
class BMP388(object):
"""docstring for BMP388"""
def __init__(self, address=I2C_ADD_BMP388):
self._address = address
self._bus = smbus.SMBus(0x01)
# Load calibration values.
if self._read_byte(BMP388_REG_ADD_WIA) == BMP388_REG_VAL_WIA:
print("Pressure sersor is BMP388!\r\n")
u8RegData = self._read_byte(BMP388_REG_ADD_STATUS)
if u8RegData & BMP388_REG_VAL_CMD_RDY:
self._write_byte(BMP388_REG_ADD_CMD,
BMP388_REG_VAL_SOFT_RESET)
time.sleep(0.01)
else:
print ("Pressure sersor NULL!\r\n")
self._write_byte(BMP388_REG_ADD_PWR_CTRL,
BMP388_REG_VAL_PRESS_EN
| BMP388_REG_VAL_TEMP_EN
| BMP388_REG_VAL_NORMAL_MODE)
self._load_calibration()
def _read_byte(self, cmd):
return self._bus.read_byte_data(self._address, cmd)
def _read_s8(self, cmd):
result = self._read_byte(cmd)
if result > 128:
result -= 256
return result
def _read_u16(self, cmd):
LSB = self._bus.read_byte_data(self._address, cmd)
MSB = self._bus.read_byte_data(self._address, cmd + 0x01)
return (MSB << 0x08) + LSB
def _read_s16(self, cmd):
result = self._read_u16(cmd)
if result > 32767:
result -= 65536
return result
def _write_byte(self, cmd, val):
self._bus.write_byte_data(self._address, cmd, val)
def _load_calibration(self):
print ("_load_calibration\r\n")
self.T1 = self._read_u16(BMP388_REG_ADD_T1_LSB)
self.T2 = self._read_u16(BMP388_REG_ADD_T2_LSB)
self.T3 = self._read_s8(BMP388_REG_ADD_T3)
self.P1 = self._read_s16(BMP388_REG_ADD_P1_LSB)
self.P2 = self._read_s16(BMP388_REG_ADD_P2_LSB)
self.P3 = self._read_s8(BMP388_REG_ADD_P3)
self.P4 = self._read_s8(BMP388_REG_ADD_P4)
self.P5 = self._read_u16(BMP388_REG_ADD_P5_LSB)
self.P6 = self._read_u16(BMP388_REG_ADD_P6_LSB)
self.P7 = self._read_s8(BMP388_REG_ADD_P7)
self.P8 = self._read_s8(BMP388_REG_ADD_P8)
self.P9 = self._read_s16(BMP388_REG_ADD_P9_LSB)
self.P10 = self._read_s8(BMP388_REG_ADD_P10)
self.P11 = self._read_s8(BMP388_REG_ADD_P11)
# print(self.T1)
# print(self.T2)
# print(self.T3)
# print(self.P1)
# print(self.P2)
# print(self.P3)
# print(self.P4)
# print(self.P5)
# print(self.P6)
# print(self.P7)
# print(self.P8)
# print(self.P9)
# print(self.P10)
# print(self.P11)
def compensate_temperature(self, adc_T):
partial_data1 = adc_T - 256 * self.T1
partial_data2 = self.T2 * partial_data1
partial_data3 = partial_data1 * partial_data1
partial_data4 = partial_data3 * self.T3
partial_data5 = partial_data2 * 262144 + partial_data4
partial_data6 = partial_data5 / 4294967296
self.T_fine = partial_data6
comp_temp = partial_data6 * 25 / 16384
return comp_temp
def compensate_pressure(self, adc_P):
partial_data1 = self.T_fine * self.T_fine
partial_data2 = partial_data1 / 0x40
partial_data3 = partial_data2 * self.T_fine / 256
partial_data4 = self.P8 * partial_data3 / 0x20
partial_data5 = self.P7 * partial_data1 * 0x10
partial_data6 = self.P6 * self.T_fine * 4194304
offset = self.P5 * 140737488355328 + partial_data4 \
+ partial_data5 + partial_data6
partial_data2 = self.P4 * partial_data3 / 0x20
partial_data4 = self.P3 * partial_data1 * 0x04
partial_data5 = (self.P2 - 16384) * self.T_fine * 2097152
sensitivity = (self.P1 - 16384) * 70368744177664 \
+ partial_data2 + partial_data4 + partial_data5
partial_data1 = sensitivity / 16777216 * adc_P
partial_data2 = self.P10 * self.T_fine
partial_data3 = partial_data2 + 65536 * self.P9
partial_data4 = partial_data3 * adc_P / 8192
partial_data5 = partial_data4 * adc_P / 512
partial_data6 = adc_P * adc_P
partial_data2 = self.P11 * partial_data6 / 65536
partial_data3 = partial_data2 * adc_P / 128
partial_data4 = offset / 0x04 + partial_data1 + partial_data5 \
+ partial_data3
comp_press = partial_data4 * 25 / 1099511627776
return comp_press
def get_temperature_and_pressure_and_altitude(self):
"""Returns pressure in Pa as double. Output value of "6386.2"equals 96386.2 Pa = 963.862 hPa."""
xlsb = self._read_byte(BMP388_REG_ADD_TEMP_XLSB)
lsb = self._read_byte(BMP388_REG_ADD_TEMP_LSB)
msb = self._read_byte(BMP388_REG_ADD_TEMP_MSB)
adc_T = (msb << 0x10) + (lsb << 0x08) + xlsb
temperature = self.compensate_temperature(adc_T)
xlsb = self._read_byte(BMP388_REG_ADD_PRESS_XLSB)
lsb = self._read_byte(BMP388_REG_ADD_PRESS_LSB)
msb = self._read_byte(BMP388_REG_ADD_PRESS_MSB)
adc_P = (msb << 0x10) + (lsb << 0x08) + xlsb
pressure = self.compensate_pressure(adc_P)
altitude = 4433000 * (0x01 - pow(pressure / 100.0 / 101325.0,
0.1903))
return (temperature, pressure, altitude)
if __name__ == '__main__':
import time
print("BMP388 Test Program ...\n")
bmp388 = BMP388()
while True:
time.sleep(0.5)
temperature,pressure,altitude = bmp388.get_temperature_and_pressure_and_altitude()
print(' Temperature = %.1f Pressure = %.2f Altitude =%.2f '%(temperature/100.0,pressure/100.0,altitude/100.0))Peter --OzzMaker.com --
