BME280.cpp

00001 #include "mbed.h"
00002 #include "BME280.h"
00003 
00004 /* internal registers */
00005 #define REG_HUM_LSB    0xFE
00006 #define REG_HUM_MSB    0xFD
00007 #define REG_TEMP_XLSB  0xFC
00008 #define REG_TEMP_LSB   0xFB
00009 #define REG_TEMP_MSB   0xFA
00010 #define REG_PRESS_XLSB 0xF9
00011 #define REG_PRESS_LSB  0xF8
00012 #define REG_PRESS_MSB  0xF7
00013 #define REG_CONFIG     0xF5
00014 #define REG_CTRL_MEAS  0xF4
00015 #define REG_STATUS     0xF3
00016 #define REG_CTRL_HUM   0xF2
00017 #define REG_RESET      0xE0
00018 #define REG_ID         0xD0
00019 
00020 #define REG_CALIB00   0x88
00021 #define REG_CALIB25   0xA1
00022 #define REG_CALIB26   0xE1
00023 #define REG_CALIB41   0xF0
00024 
00025 /** Trimming parameters */
00026 /* temperature */
00027 #define REG_T1_LSB 0x88
00028 #define REG_T1_MSB 0x89
00029 #define REG_T2_LSB 0x8A
00030 #define REG_T2_MSB 0x8B
00031 #define REG_T3_LSB 0x8C
00032 #define REG_T3_MSB 0x8D
00033 /* pressure */
00034 #define REG_P1_LSB 0x8E
00035 #define REG_P1_MSB 0x8F
00036 #define REG_P2_LSB 0x90
00037 #define REG_P2_MSB 0x91
00038 #define REG_P3_LSB 0x92
00039 #define REG_P3_MSB 0x93
00040 #define REG_P4_LSB 0x94
00041 #define REG_P4_MSB 0x95
00042 #define REG_P5_LSB 0x96
00043 #define REG_P5_MSB 0x97
00044 #define REG_P6_LSB 0x98
00045 #define REG_P6_MSB 0x99
00046 #define REG_P7_LSB 0x9A
00047 #define REG_P7_MSB 0x9B
00048 #define REG_P8_LSB 0x9C
00049 #define REG_P8_MSB 0x9D
00050 #define REG_P9_LSB 0x9E
00051 #define REG_P9_MSB 0x9F
00052 /* humidity */
00053 #define REG_H1     0xA1
00054 #define REG_H2_LSB 0xE1
00055 #define REG_H2_MSB 0xE2
00056 #define REG_H3     0xE3
00057 #define REG_H4     0xE4
00058 #define REG_H5     0xE5
00059 #define REG_H6     0xE7
00060 
00061 /*
00062  * Register description
00063  * 0xD0 "id"
00064  *  chip identification number chip_id[7:0], which is 0x60
00065  *
00066  * 0xE0 "reset"
00067  *  Software reset register, writing 0xB6 causes complete power-on-reset.
00068  *
00069  * 0xF2 "ctrl_hum"
00070  *  Specifies the humidity data acquision options.
00071  *  Note: Changes to this register only become effective after a write
00072  *  operaion to "ctrl_meas".
00073  * bit[2:0] osrs_h[2:0] Controls oversampling of humidity data.
00074  *  000: Skipped (output set to 0x8000)
00075  *  001: oversampling x1
00076  *  010: oversampling x2
00077  *  011: oversampling x4
00078  *  100: oversampling x8
00079  *  101, others, oversampling x16
00080  *
00081  * 0xF3 "status"
00082  * bit[3] measuring[0] Automatically set to '1' during conversion 
00083  *        and back to '0' when done
00084  * bit[0] im_update[0] Automatically set to '1' during NVM data copy 
00085  *        and back to '0' when done
00086  *
00087  * 0xF4 "ctrl_meas" 
00088  *  Specifies the pressure and temperature data acquision options.
00089  *  Note: This register needs to be written after canging "ctrl_hum" to take effect.
00090  * bit[7:5] osrs_t[2:0] Controls oversampling of temperature data
00091  *  bit value is similar to osrs_h (except 000 output set to 0x80000)
00092  * bit[4:2] osrs_p[2:0] Controls oversampling of pressure data
00093  *  bit value is similar to osrs_h (except 000 output set to 0x80000)
00094  * bit[1:0] mode[1:0] Controls the sensor mode.
00095  *  00: Sleep mode
00096  *  01: Forced mode
00097  *  10: Forced mode
00098  *  11: Normal mode
00099  *
00100  * 0xF5 "config" 
00101  *  Specifies the rate, filter and interface options.
00102  *  Writes to "config" in normal mode may be ignored.
00103  *  In sleep mode writes are not ignored.
00104  * bit[7:5] t_sb[2:0] Controls inactive duration t_standby in normal mode.
00105  * 000:    0.5 [ms]
00106  * 001:   62.5 [ms]
00107  * 010:  125   [ms]
00108  * 011:  250   [ms]
00109  * 100:  500   [ms]
00110  * 101: 1000   [ms]
00111  * 110:   10   [ms]
00112  * 111:   20   [ms]
00113  * bit[4:2] filter[2:0] Controls the time constant of the IIR filter.
00114  * 000: Filter off
00115  * 001:  2
00116  * 010:  4
00117  * 011:  8
00118  * 100, others: 16
00119  *
00120  * 0xF7 .. 0xF9 "press" (_msb, _lsb, _xlsb)
00121  * 0xF7 bit[7:0] press_msb[7:0]   MSB part up[19:12]
00122  * 0xF8 bit[7:0] press_lsb[7:0]   LSB part  up[11:4]
00123  * 0xF9 bit[7:4] press_xlsb[3:0] XLSB part   up[3:0]
00124  *
00125  * 0xFA .. 0xFC "temp" (_msb, _lsb, _xlsb)
00126  * 0xFA bit[7:0] temp_msb[7:0]   MSB part ut[19:12]
00127  * 0xFB bit[7:0] temp_lsb[7:0]   LSB part  ut[11:4]
00128  * 0xFC bit[7:4] temp_xlsp[3:0] XLSB part   ut[3:0]
00129  *
00130  * 0xFD .. 0xFE "hum" (_msb, _lsb)
00131  * 0xFD bit[7:0] hum_msb[7:0]    MSB part uh[15:8]
00132  * 0xFE bit[7:0] hum_lsb[7:0]    LSB part  uh[7:0]
00133  */
00134  /*
00135   * Compensation parameter storage, naming and data type
00136   * Register addr,  Register content,    Data type
00137   * 0x88/0x89,      dig_T1[7:0]/[15:8],  unsigned short
00138   * 0x8A/0x8B,      dig_T2[7:0]/[15:8],    signed short
00139   * 0x8C/0x8D,      dig_T3[7:0]/[15:8],    signed short
00140   * 0x8E/0x8F,      dig_P1[7:0]/[15:8],  unsigned short
00141   * 0x90/0x91,      dig_P2[7:0]/[15:8],    signed short
00142   * 0x92/0x93,      dig_P3[7:0]/[15:8],    signed short
00143   * 0x94/0x95,      dig_P4[7:0]/[15:8],    signed short
00144   * 0x96/0x97,      dig_P5[7:0]/[15:8],    signed short
00145   * 0x98/0x99,      dig_P6[7:0]/[15:8],    signed short
00146   * 0x9A/0x9B,      dig_P7[7:0]/[15:8],    signed short
00147   * 0x9C/0x9D,      dig_P8[7:0]/[15:8],    signed short
00148   * 0x9E/0x9F,      dig_P9[7:0]/[15:8],    signed short
00149   * 0xA1,           dig_H1[7:0],         unsigned char
00150   * 0xE1/0xE2,      dig_H2[7:0]/[15:8],    signed short
00151   * 0xE3,           dig_H3[7:0],         unsigned char
00152   * 0xE4/0xE5[3:0], dig_H4[11:4]/[3:0]  signed short
00153   * 0xE5[7:4]/0xE6, dig_H5[3:0]/[11:4]  signed short
00154   * 0xE7,           dig_H6[7:0],        signed char
00155   */
00156 
00157 void BME280::init(void)
00158 {
00159     uint8_t data[18] ;
00160     
00161     data[0] = REG_CTRL_HUM ;
00162     data[1] = 0x03 ; /* Humidity oversampling x4 */
00163     writeRegs(data, 2) ;
00164     
00165     data[0] = REG_CTRL_MEAS ;
00166     data[1] = (0x3 << 5) /* temp oversample x4 */
00167             | (0x3 << 2) /* pres oversample x4 */
00168             | (0x00)      /* Sleep Mode */
00169             ;
00170     writeRegs(data, 2) ;
00171     
00172     data[0] = REG_CONFIG ;
00173     data[1] = (0x4 << 5) /* standby 500ms */
00174             | (0x0 << 2) /* filter off */
00175             | (0x0)      /* spi 4wire mode */   
00176             ;
00177     writeRegs(data, 2) ;
00178     
00179     /* read dig_T regs */
00180     readRegs(REG_T1_LSB, data, 6) ;
00181     dig_T1 = (data[1] << 8) | data[0] ;
00182     dig_T2 = (data[3] << 8) | data[2] ;
00183     dig_T3 = (data[5] << 8) | data[4] ;
00184 // printf("dig_T1:0x%04X, dig_T2:0x%04X, dig_T3:0x%04X\n",dig_T1, dig_T2, dig_T3) ;
00185     
00186     /* read dig_P regs */
00187     readRegs(REG_P1_LSB, data, 18) ;
00188     dig_P1 = (data[ 1] << 8) | data[ 0] ;
00189     dig_P2 = (data[ 3] << 8) | data[ 2] ;
00190     dig_P3 = (data[ 5] << 8) | data[ 4] ;
00191     dig_P4 = (data[ 7] << 8) | data[ 6] ;
00192     dig_P5 = (data[ 9] << 8) | data[ 8] ;
00193     dig_P6 = (data[11] << 8) | data[10] ;
00194     dig_P7 = (data[13] << 8) | data[12] ;
00195     dig_P8 = (data[15] << 8) | data[14] ;
00196     dig_P9 = (data[17] << 8) | data[16] ;
00197 // printf("dig_P1:0x%04X, dig_P2:0x%04X, dig_P3:0x%04X\n",dig_P1, dig_P2, dig_P3) ;
00198 // printf("dig_P4:0x%04X, dig_P5:0x%04X, dig_P6:0x%04X\n",dig_P4, dig_P5, dig_P6) ;
00199 // printf("dig_P7:0x%04X, dig_P8:0x%04X, dig_P9:0x%04X\n",dig_P7, dig_P8, dig_P9) ;
00200     
00201     /* read dig_H regs */
00202     readRegs(REG_H1, data, 1) ;
00203     dig_H1 = data[0] ;
00204     readRegs(REG_H2_LSB, data, 2) ;
00205     dig_H2 = (data[1] << 8) | data[0] ;
00206     readRegs(REG_H3, data, 1) ;
00207     dig_H3 = data[0] ;
00208     readRegs(REG_H4, data, 3) ; 
00209     dig_H4 = (data[0] << 4) | (data[1] & 0x0F) ;
00210     dig_H5 = (data[2] << 4) | (data[1] >> 4) ;  
00211     readRegs(REG_H6, data, 1) ;
00212     dig_H6 = data[0] ;
00213 // printf("dig_H1:0x%04X, dig_H2:0x%04X, dig_H3:0x%04X\n",dig_H1, dig_H2, dig_H3) ;    
00214 // printf("dig_H4:0x%04X, dig_H5:0x%04X, dig_H6:0x%04X\n",dig_H4, dig_H5, dig_H6) ;   
00215  
00216     trigger() ; /* dummy measure */
00217 }
00218 
00219 BME280::BME280(PinName sda, PinName scl, int addr) 
00220 {
00221     m_i2c = new I2C(sda, scl) ;
00222     m_addr = (addr << 1) ;
00223     m_spi = 0 ;
00224     m_cs = 0 ;
00225     init() ;
00226 }
00227 
00228 BME280::BME280(PinName sck, PinName miso, PinName mosi, PinName cs) 
00229 {
00230     m_cs = new DigitalOut(cs, 1) ;
00231     m_spi = new SPI(mosi, miso, sck) ;
00232     m_spi->format(8, 3) ;
00233     m_i2c = 0 ;
00234     m_addr = 0 ;
00235     init() ;
00236 }
00237 
00238 BME280::~BME280() 
00239 {
00240     if (m_spi) { 
00241         delete m_spi ;
00242         delete m_cs ; 
00243     }
00244     if (m_i2c) { 
00245         delete m_i2c ; 
00246         m_addr = 0 ;
00247     }
00248 }
00249 
00250 void BME280::i2c_readRegs(int addr, uint8_t * data, int len) {
00251     char t[1] = {addr} ;
00252     m_i2c->write(m_addr, t, 1, true) ;
00253     m_i2c->read(m_addr, (char*)data, len) ;
00254 }
00255 
00256 void BME280::i2c_writeRegs(uint8_t * data, int len) {
00257    m_i2c->write(m_addr, (char *)data, len) ;
00258 }
00259 
00260 void BME280::spi_readRegs(int addr, uint8_t * data, int len) {
00261     *m_cs = 0 ;
00262     m_spi->write(addr | 0x80) ;
00263     for (int i = 0 ; i < len ; i++ ) {    
00264       data[i] = m_spi->write((addr+i)|0x80) ; 
00265     } 
00266     m_spi->write(0x00) ; // to terminate read mode
00267     *m_cs = 1 ;
00268 }
00269 
00270 void BME280::spi_writeRegs(uint8_t * data, int len) {
00271    *m_cs = 0 ;
00272    for (int i = 0 ; i < len-1 ; i++ ) {
00273       m_spi->write((data[0]+i)^0x80) ; /* register address */
00274       m_spi->write(data[i+1]) ; /* data to write */
00275 
00276    }
00277    *m_cs = 1 ;
00278 }
00279 
00280 void BME280::readRegs(int addr, uint8_t *data, int len) 
00281 {
00282     if (m_spi) {
00283         spi_readRegs(addr, data, len) ;
00284     } else if (m_i2c) {
00285         i2c_readRegs(addr, data, len) ;
00286     }
00287 }
00288 
00289 void BME280::writeRegs(uint8_t *data, int len) 
00290 {
00291     if (m_spi) {
00292         spi_writeRegs(data, len) ;
00293     } else if (m_i2c) {
00294         i2c_writeRegs(data, len) ;
00295     }
00296 }
00297 
00298 void BME280::reset(void)
00299 {
00300     uint8_t data[2] ;
00301     data[0] = REG_RESET ;
00302     data[1] = 0xB6 ;
00303     writeRegs(data, 2) ;
00304 }
00305 
00306 void BME280::trigger(void)
00307 {
00308     uint8_t data[2] ;
00309     readRegs(REG_CTRL_MEAS, &data[1], 1) ;
00310     
00311     data[0] = REG_CTRL_MEAS ;
00312     data[1] = (data[1] & 0xFC) /* keep oversampling */
00313             | (0x2)      /* Forced Mode */
00314             ;
00315     writeRegs(data, 2) ;
00316 }
00317 
00318 uint8_t BME280::busy(void)
00319 {
00320     uint8_t data[1] ;
00321     readRegs(REG_STATUS, data, 1) ;
00322     return( data[0] & 0x9 ) ;
00323 }
00324 
00325 uint8_t BME280::getID(void)
00326 {
00327     uint8_t data[1] ;
00328     readRegs(REG_ID, data, 1) ;
00329     return(data[0]) ;
00330 }
00331 
00332 float BME280::getTemperature(void) 
00333 {
00334     float tempf ;
00335     uint8_t data[3] ;
00336     BME280_S32_t var1, var2, T ;
00337     BME280_S32_t adc_T ;
00338     
00339     readRegs(REG_TEMP_MSB, data, 3) ;
00340     adc_T = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4);
00341     
00342     var1 = ((((adc_T>>3) - ((BME280_S32_t)dig_T1<<1))) * ((BME280_S32_t)dig_T2)) >> 11;
00343     var2 = (((((adc_T>>4) - ((BME280_S32_t)dig_T1)) * ((adc_T>>4) - ((BME280_S32_t)dig_T1))) >> 12) *
00344         ((BME280_S32_t)dig_T3)) >> 14;
00345     t_fine = var1 + var2;
00346     T = (t_fine * 5 + 128) >> 8;
00347     
00348     tempf = (float)T;
00349     return (tempf/100.0f);
00350 }
00351 
00352 float BME280::getPressure(void) 
00353 {
00354     BME280_S32_t adc_P ;
00355     BME280_S64_t var1, var2, p ;
00356     float pressf;
00357     uint8_t data[3];
00358  
00359     readRegs(REG_PRESS_MSB, data, 3) ;
00360     adc_P = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4);
00361  
00362     var1 = ((BME280_S64_t)t_fine) - 128000;
00363     var2 = var1 * var1 * (BME280_S64_t)dig_P6;
00364     var2 = var2 + ((var1*(BME280_S64_t)dig_P5)<<17);
00365     var2 = var2 + (((BME280_S64_t)dig_P4)<<35);
00366     var1 = ((var1 * var1 * (BME280_S64_t)dig_P3)>>8) + ((var1 * (BME280_S64_t)dig_P2)<<12);
00367     var1 = (((((BME280_S64_t)1)<<47)+var1))*((BME280_S64_t)dig_P1)>>33;
00368     if (var1 == 0) {
00369         return 0; // avoid exception caused by division by zero
00370     }
00371     p = 1048576-adc_P;
00372     p = (((p<<31)-var2)*3125)/var1;
00373     var1 = (((BME280_S64_t)dig_P9) * (p>>13) * (p>>13)) >> 25;
00374     var2 = (((BME280_S64_t)dig_P8) * p) >> 19;
00375     p = ((p + var1 + var2) >> 8) + (((BME280_S64_t)dig_P7)<<4);
00376  
00377     pressf = (float)(p >> 8) ;
00378     return (pressf/100.0f);
00379 }
00380 
00381 float BME280::getHumidity(void) 
00382 {
00383     BME280_S32_t adc_H;
00384     BME280_S32_t v_x1_u32r ;
00385     float humf;
00386     uint8_t data[2];
00387  
00388     readRegs(REG_HUM_MSB, data, 2) ;
00389     adc_H = (data[0] << 8) | data[1];
00390  
00391     v_x1_u32r = (t_fine - ((BME280_S32_t)76800));
00392     v_x1_u32r = (((((adc_H << 14) - (((BME280_S32_t)dig_H4) << 20) - (((BME280_S32_t)dig_H5) * v_x1_u32r)) +
00393         ((BME280_S32_t)16384)) >> 15) * (((((((v_x1_u32r * ((BME280_S32_t)dig_H6)) >> 10) * (((v_x1_u32r *
00394         ((BME280_S32_t)dig_H3)) >> 11) + ((BME280_S32_t)32768))) >> 10) + ((BME280_S32_t)2097152)) *
00395         ((BME280_S32_t)dig_H2) + 8192) >> 14));
00396     v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) * ((BME280_S32_t)dig_H1)) >> 4));
00397     v_x1_u32r = (v_x1_u32r < 0 ? 0 : v_x1_u32r);
00398     v_x1_u32r = (v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r);
00399     humf = (float)(v_x1_u32r >> 12) ;
00400 
00401     return (humf/1024.0f);
00402 }