#include "Arduino.h"
#include <Wire.h>
#include <SPI.h>
#include "Adafruit_BMP280.h"
static bmp280_calib_data bmp280_calib;
/***************************************************************************
PRIVATE FUNCTIONS
***************************************************************************/
Adafruit_BMP280::Adafruit_BMP280()
: _cs(-1), _mosi(-1), _miso(-1), _sck(-1)
{ }
Adafruit_BMP280::Adafruit_BMP280(int8_t cspin)
: _cs(cspin), _mosi(-1), _miso(-1), _sck(-1)
{ }
Adafruit_BMP280::Adafruit_BMP280(int8_t cspin, int8_t mosipin, int8_t misopin, int8_t sckpin)
: _cs(cspin), _mosi(mosipin), _miso(misopin), _sck(sckpin)
{ }
bool Adafruit_BMP280::begin(uint8_t a) {
_i2caddr = a;
if (_cs == -1) {
// i2c
Wire.begin();
} else {
digitalWrite(_cs, HIGH);
pinMode(_cs, OUTPUT);
if (_sck == -1) {
// hardware SPI
SPI.begin();
} else {
// software SPI
pinMode(_sck, OUTPUT);
pinMode(_mosi, OUTPUT);
pinMode(_miso, INPUT);
}
}
if (read8(BMP280_REGISTER_CHIPID) != 0x58)
return false;
readCoefficients();
write8(BMP280_REGISTER_CONTROL, 0x3F);
return true;
}
uint8_t Adafruit_BMP280::spixfer(uint8_t x) {
if (_sck == -1)
return SPI.transfer(x);
// software spi
//Serial.println("Software SPI");
uint8_t reply = 0;
for (int i=7; i>=0; i--) {
reply <<= 1;
digitalWrite(_sck, LOW);
digitalWrite(_mosi, x & (1<<i));
digitalWrite(_sck, HIGH);
if (digitalRead(_miso))
reply |= 1;
}
return reply;
}
/**************************************************************************/
/*!
@brief Writes an 8 bit value over I2C/SPI
*/
/**************************************************************************/
void Adafruit_BMP280::write8(byte reg, byte value)
{
if (_cs == -1) {
Wire.beginTransmission((uint8_t)_i2caddr);
Wire.write((uint8_t)reg);
Wire.write((uint8_t)value);
Wire.endTransmission();
} else {
if (_sck == -1)
SPI.beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
digitalWrite(_cs, LOW);
spixfer(reg & ~0x80); // write, bit 7 low
spixfer(value);
digitalWrite(_cs, HIGH);
if (_sck == -1)
SPI.endTransaction(); // release the SPI bus
}
}
/**************************************************************************/
/*!
@brief Reads an 8 bit value over I2C
*/
/**************************************************************************/
uint8_t Adafruit_BMP280::read8(byte reg)
{
uint8_t value;
if (_cs == -1) {
Wire.beginTransmission((uint8_t)_i2caddr);
Wire.write((uint8_t)reg);
Wire.endTransmission();
Wire.requestFrom((uint8_t)_i2caddr, (byte)1);
value = Wire.read();
Wire.endTransmission();
} else {
if (_sck == -1)
SPI.beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
digitalWrite(_cs, LOW);
spixfer(reg | 0x80); // read, bit 7 high
value = spixfer(0);
digitalWrite(_cs, HIGH);
if (_sck == -1)
SPI.endTransaction(); // release the SPI bus
}
return value;
}
/**************************************************************************/
/*!
@brief Reads a 16 bit value over I2C
*/
/**************************************************************************/
uint16_t Adafruit_BMP280::read16(byte reg)
{
uint16_t value;
if (_cs == -1) {
Wire.beginTransmission((uint8_t)_i2caddr);
Wire.write((uint8_t)reg);
Wire.endTransmission();
Wire.requestFrom((uint8_t)_i2caddr, (byte)2);
value = (Wire.read() << 8) | Wire.read();
Wire.endTransmission();
} else {
if (_sck == -1)
SPI.beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
digitalWrite(_cs, LOW);
spixfer(reg | 0x80); // read, bit 7 high
value = (spixfer(0) << 8) | spixfer(0);
digitalWrite(_cs, HIGH);
if (_sck == -1)
SPI.endTransaction(); // release the SPI bus
}
return value;
}
uint16_t Adafruit_BMP280::read16_LE(byte reg) {
uint16_t temp = read16(reg);
return (temp >> 8) | (temp << 8);
}
/**************************************************************************/
/*!
@brief Reads a signed 16 bit value over I2C
*/
/**************************************************************************/
int16_t Adafruit_BMP280::readS16(byte reg)
{
return (int16_t)read16(reg);
}
int16_t Adafruit_BMP280::readS16_LE(byte reg)
{
return (int16_t)read16_LE(reg);
}
/**************************************************************************/
/*!
@brief Reads the factory-set coefficients
*/
/**************************************************************************/
void Adafruit_BMP280::readCoefficients(void)
{
bmp280_calib.dig_T1 = read16_LE(BMP280_REGISTER_DIG_T1);
bmp280_calib.dig_T2 = readS16_LE(BMP280_REGISTER_DIG_T2);
bmp280_calib.dig_T3 = readS16_LE(BMP280_REGISTER_DIG_T3);
bmp280_calib.dig_P1 = read16_LE(BMP280_REGISTER_DIG_P1);
bmp280_calib.dig_P2 = readS16_LE(BMP280_REGISTER_DIG_P2);
bmp280_calib.dig_P3 = readS16_LE(BMP280_REGISTER_DIG_P3);
bmp280_calib.dig_P4 = readS16_LE(BMP280_REGISTER_DIG_P4);
bmp280_calib.dig_P5 = readS16_LE(BMP280_REGISTER_DIG_P5);
bmp280_calib.dig_P6 = readS16_LE(BMP280_REGISTER_DIG_P6);
bmp280_calib.dig_P7 = readS16_LE(BMP280_REGISTER_DIG_P7);
bmp280_calib.dig_P8 = readS16_LE(BMP280_REGISTER_DIG_P8);
bmp280_calib.dig_P9 = readS16_LE(BMP280_REGISTER_DIG_P9);
}
/**************************************************************************/
/*!
*/
/**************************************************************************/
float Adafruit_BMP280::readTemperature(void)
{
int32_t var1, var2;
int32_t adc_T = read16(BMP280_REGISTER_TEMPDATA);
adc_T <<= 8;
adc_T |= read8(BMP280_REGISTER_TEMPDATA+2);
adc_T >>= 4;
var1 = ((((adc_T>>3) - ((int32_t)bmp280_calib.dig_T1 <<1))) *
((int32_t)bmp280_calib.dig_T2)) >> 11;
var2 = (((((adc_T>>4) - ((int32_t)bmp280_calib.dig_T1)) *
((adc_T>>4) - ((int32_t)bmp280_calib.dig_T1))) >> 12) *
((int32_t)bmp280_calib.dig_T3)) >> 14;
t_fine = var1 + var2;
float T = (t_fine * 5 + 128) >> 8;
return T/100;
}
/**************************************************************************/
/*!
*/
/**************************************************************************/
float Adafruit_BMP280::readPressure(void) {
int64_t var1, var2, p;
int32_t adc_P = read16(BMP280_REGISTER_PRESSUREDATA);
adc_P <<= 8;
adc_P |= read8(BMP280_REGISTER_PRESSUREDATA+2);
adc_P >>= 4;
var1 = ((int64_t)t_fine) - 128000;
var2 = var1 * var1 * (int64_t)bmp280_calib.dig_P6;
var2 = var2 + ((var1*(int64_t)bmp280_calib.dig_P5)<<17);
var2 = var2 + (((int64_t)bmp280_calib.dig_P4)<<35);
var1 = ((var1 * var1 * (int64_t)bmp280_calib.dig_P3)>>8) +
((var1 * (int64_t)bmp280_calib.dig_P2)<<12);
var1 = (((((int64_t)1)<<47)+var1))*((int64_t)bmp280_calib.dig_P1)>>33;
if (var1 == 0) {
return 0; // avoid exception caused by division by zero
}
p = 1048576 - adc_P;
p = (((p<<31) - var2)*3125) / var1;
var1 = (((int64_t)bmp280_calib.dig_P9) * (p>>13) * (p>>13)) >> 25;
var2 = (((int64_t)bmp280_calib.dig_P8) * p) >> 19;
p = ((p + var1 + var2) >> 8) + (((int64_t)bmp280_calib.dig_P7)<<4);
return (float)p/256;
}
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