壓力感測器實作 – BMP280數位式氣壓感測器
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程式列表
Python - BMP280_const.py
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#
Default device I2C address BMP280_ADDR
= 0x76 #
BMP280 Temperature Registers BMP280_REGISTER_DIG_T1
= 0x88 BMP280_REGISTER_DIG_T2
= 0x8A BMP280_REGISTER_DIG_T3
= 0x8C #
BMP280 Pressure Registers BMP280_REGISTER_DIG_P1
= 0x8E BMP280_REGISTER_DIG_P2
= 0x90 BMP280_REGISTER_DIG_P3
= 0x92 BMP280_REGISTER_DIG_P4
= 0x94 BMP280_REGISTER_DIG_P5
= 0x96 BMP280_REGISTER_DIG_P6
= 0x98 BMP280_REGISTER_DIG_P7
= 0x9A BMP280_REGISTER_DIG_P8
= 0x9C BMP280_REGISTER_DIG_P9
= 0x9E BMP280_REGISTER_ID = 0xD0 BMP280_REGISTER_RESET = 0xE0 BMP280_REGISTER_STATUS
= 0xF3 BMP280_REGISTER_CONTROL
= 0xF4 BMP280_REGISTER_CONFIG
= 0xF5 #Pressure
measurments BMP280_REGISTER_PRESSUREDATA_MSB
= 0xF7 BMP280_REGISTER_PRESSUREDATA_LSB
= 0xF8 BMP280_REGISTER_PRESSUREDATA_XLSB
= 0xF9 #Temperature
measurments BMP280_REGISTER_TEMPDATA_MSB
= 0xFA BMP280_REGISTER_TEMPDATA_LSB
= 0xFB BMP280_REGISTER_TEMPDATA_XLSB
= 0xFC #
Commands BMP280_READCMD
= 0x3F |
Python - BMP280.py
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""" Reference:
https://bitbucket.org/MattHawkinsUK/rpispy-misc/raw/master/python/bme280.py """ from
machine import I2C import
utime from
BMP280_const import * class BMP280(object): def __init__(self,
i2c, address=0x76): self._i2c
= i2c self._address
= address def getShort(self,
data, index): # return two bytes
from data as a signed 16-bit value result = (data[index+1] << 8) +
data[index] if (result>32767) : result -= 32768 return
result def getUShort(self,
data, index): # return two bytes
from data as an unsigned 16-bit value return (data[index+1] << 8) +
data[index] def getChar(self,
data,index): # return one byte
from data as a signed char result =
data[index] if
result > 127: result -= 256 return
result def getUChar(self,
data,index): # return one byte
from data as an unsigned char result = data[index] & 0xFF return
result def write_byte_data(self,
reg_addr, data): self._i2c.send(bytearray([reg_addr,data]),self._address) def read_i2c_block_data(self,
reg_addr, size=1): data = bytearray(size) self._i2c.send(bytearray([reg_addr]),self._address) self._i2c.recv(data,self._address) return
data def readBMP280ID(self): # Chip ID Register
Address result =
self.read_i2c_block_data(BMP280_REGISTER_ID, 1) chip_id =result[0] return (chip_id) def readBMP280All(self): # Oversample
setting - page 27 OVERSAMPLE_TEMP = 2 OVERSAMPLE_PRES = 2 MODE = 1 control =
OVERSAMPLE_TEMP<<5 |
OVERSAMPLE_PRES<<2 |
MODE self.write_byte_data(BMP280_REGISTER_CONTROL,
control) # Read blocks of
calibration data from EEPROM # See Page 22 data
sheet cal1 = bytearray(24) cal1 =
self.read_i2c_block_data(BMP280_REGISTER_DIG_T1, 24) # Convert byte
data to word values dig_T1 =
self.getUShort(cal1, 0) dig_T2 =
self.getShort(cal1, 2) dig_T3 =
self.getShort(cal1, 4) dig_P1 =
self.getUShort(cal1, 6) dig_P2 =
self.getShort(cal1, 8) dig_P3 =
self.getShort(cal1, 10) dig_P4 =
self.getShort(cal1, 12) dig_P5 =
self.getShort(cal1, 14) dig_P6 =
self.getShort(cal1, 16) dig_P7 =
self.getShort(cal1, 18) dig_P8 =
self.getShort(cal1, 20) dig_P9 = self.getShort(cal1, 22) # Wait in ms
(Datasheet Appendix B: Measurement time and current calculation) wait_time = 1.25 + (2.3 *
OVERSAMPLE_TEMP) + ((2.3 *
OVERSAMPLE_PRES) + 0.575) utime.sleep(wait_time/1000) # Wait the
required time # Read
temperature/pressure data =
self.read_i2c_block_data(BMP280_REGISTER_PRESSUREDATA_MSB, 8) pres_raw = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4) temp_raw = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4) #Refine temperature var1 = ((((temp_raw>>3)-(dig_T1<<1)))*(dig_T2)) >> 11 var2 = (((((temp_raw>>4) - (dig_T1)) * ((temp_raw>>4) - (dig_T1))) >> 12) * (dig_T3)) >> 14 t_fine =
var1+var2 temperature = float(((t_fine
* 5) + 128) >> 8); # Refine pressure
and adjust for temperature var1 =
t_fine / 2.0 - 64000.0 var2 =
var1 * var1 *
dig_P6 / 32768.0 var2 =
var2 + var1 *
dig_P5 * 2.0 var2 =
var2 / 4.0 +
dig_P4 * 65536.0 var1 = (dig_P3
* var1 *
var1 / 524288.0 +
dig_P2 * var1) / 524288.0 var1 = (1.0 +
var1 / 32768.0) *
dig_P1 if
var1 == 0: pressure=0 else: pressure = 1048576.0 -
pres_raw pressure = ((pressure
- var2 / 4096.0) * 6250.0) /
var1 var1 =
dig_P9 * pressure *
pressure / 2147483648.0 var2 =
pressure * dig_P8 / 32768.0 pressure =
pressure + (var1
+ var2 +
dig_P7) / 16.0 return
temperature/100.0,pressure/100.0 |
Python - ePy-Lite_BMP280.py
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""" ePy-Lite_BMP280.py Read data from a digital
pressure sensor. ePy-Lite BMP280 -----------+------ 3V3 | Pin1
VCC (For powering up the module) GND | Pin2
GND (Ground) P17_SCL0 | Pin3
SCK/SCL (I2C clock) P16_SDA0 | Pin4
SDI/SDA (I2C data) | Pin5 CSB | Pin6 SDO +-------- """ from
machine import Switch #Get button KEY
library from
machine import Timer,
I2C,UART,
LED import
utime import
BMP280 BLEOUT
= True def tick3(timer): global
TimerDone,Timer5s,Timer5sDone TimerDone = True Timer5s += 1 if
Timer5s>=50 : Timer5s=0 Timer5sDone = True def key_int(): global
KeyADone KeyADone = True #
Start Function if
__name__ == '__main__': ledY =
LED('ledy') ledY.off() KeyA =
Switch('keya') #Create button A KeyA.callback(key_int) KeyADone = False timer =
Timer(3,freq=10) timer.callback(tick3) Timer5s = 0 Timer5sDone = False TimerDone = False # Declaration I2C i2c =
I2C(0,I2C.MASTER,baudrate=100000) #Create I2C0
Master Mode, Baudrate=100kHz pressure_sensor=BMP280.BMP280(i2c) (chip_id) =
pressure_sensor.readBMP280ID() print ("Chip
ID : {:x}H".format(chip_id)) utime.sleep_ms(50) if(BLEOUT): ble =
UART(1,115200) ble.write('AT+MODE_DATA\r\n') print("---
Start ---") while True: if
Timer5sDone == True: ledY.on() Temp,Press
= pressure_sensor.readBMP280All() print ('Temperature={:.2f}*C,
Pressure={:.2f}hPa'.format(Temp,Press)) if(BLEOUT): ble.write('T
= {:.2f}*C, P = {:.2f}hPa\r\n'.format (Temp,Press)) ledY.off() Timer5sDone = False if
KeyADone == True: #Press
A Key break if(BLEOUT): ble.deinit() i2c.deinit() KeyA.callback(None) print("---
End ---") |
執行結果
