Diff: BME280.cpp

Revision:

0:19fab6c64964

diff -r 000000000000 -r 19fab6c64964 BME280.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BME280.cpp	Sat Jan 02 10:32:48 2021 +0000
@@ -0,0 +1,183 @@
+#include "BME280.h"
+
+BME::BME(PinName sda, PinName scl, char slave_adr) : bme(sda, scl)
+{       
+    address=slave_adr;
+    bme.frequency(100000);
+}
+    
+void BME::initialize()
+{
+    char cmd[18]; 
+    wait_us(5000);  
+    
+    if(_debug)printf("\033[0m\033[2J\033[H ++++ BME-P register's ++++\r\n\n");
+     
+    cmd[0] = 0xF2;                  // ctrl_hum
+    cmd[1] = 0x01;                  // Humidity oversampling x1
+    bme.write(address, cmd, 2);
+ 
+    cmd[0] = 0xF4;                  // ctrl_meas
+    cmd[1] = 0x27;                  // Temparature oversampling x1, Pressure oversampling x1, Normal mode
+    bme.write(address, cmd, 2);
+ 
+    cmd[0] = 0xF5;                  // config
+    cmd[1] = 0xa0;                  // Standby 1000ms, Filter off
+    bme.write(address, cmd, 2);
+    
+    // sensor registers
+    if(_debug)printf("chip_id = 0x%x\n\n", chip_id);
+     
+    cmd[0] = 0x88;                  // read dig_T calibration regs
+    bme.write(address, cmd, 1);
+    bme.read(address, cmd, 6); 
+    dig_T1 = (cmd[1] << 8) | cmd[0];
+    dig_T2 = (cmd[3] << 8) | cmd[2];
+    dig_T3 = (cmd[5] << 8) | cmd[4]; 
+    if(_debug)printf("Temp Cal reg's:\nT1 = 0x%x\nT2 = 0x%x\nT3 = 0x%x\n\n", dig_T1, dig_T2, dig_T3);
+    
+    cmd[0] = 0x8E;                  // read dig_P calibration regs
+    bme.write(address, cmd, 1);
+    bme.read(address, cmd, 18); 
+    dig_P1 = (cmd[ 1] << 8) | cmd[ 0];
+    dig_P2 = (cmd[ 3] << 8) | cmd[ 2];
+    dig_P3 = (cmd[ 5] << 8) | cmd[ 4];
+    dig_P4 = (cmd[ 7] << 8) | cmd[ 6];
+    dig_P5 = (cmd[ 9] << 8) | cmd[ 8];
+    dig_P6 = (cmd[11] << 8) | cmd[10];
+    dig_P7 = (cmd[13] << 8) | cmd[12];
+    dig_P8 = (cmd[15] << 8) | cmd[14];
+    dig_P9 = (cmd[17] << 8) | cmd[16];    
+    if(_debug)printf("Pressure Cal reg's:\nP1 = 0x%x\nP2 = 0x%x\nP3 = 0x%x\nP4 = 0x%x\n", dig_P1, dig_P2, dig_P3, dig_P4);
+    if(_debug)printf("P5 = 0x%x\nP6 = 0x%x\nP7 = 0x%x\nP8 = 0x%x\nP9 = 0x%x\n\n", dig_P5, dig_P6, dig_P7, dig_P8, dig_P9);
+    
+    if(chip_id == 0x60){            // Only BME280 has Humidity     
+        cmd[0] = 0xA1;              // read dig_H calibration LSB regs
+        bme.write(address, cmd, 1);
+        bme.read(address, cmd, 1);
+        cmd[1] = 0xE1;              // read dig_H calibration MSB regs
+        bme.write(address, &cmd[1], 1);
+        bme.read(address, &cmd[1], 7);
+        dig_H1 = cmd[0];
+        dig_H2 = (cmd[2] << 8) | cmd[1];
+        dig_H3 = cmd[3];
+        dig_H4 = (cmd[4] << 4) | (cmd[5] & 0x0f);
+        dig_H5 = (cmd[6] << 4) | ((cmd[5]>>4) & 0x0f);
+        dig_H6 = cmd[7];    
+        if(_debug)printf("Humidity Cal reg's:\nH1 = 0x%x\nH2 = 0x%x\nH3 = 0x%x\n", dig_H1, dig_H2, dig_H3);
+        if(_debug)printf("H4 = 0x%x\nH5 = 0x%x\nH6 = 0x%x\n", dig_H4, dig_H5, dig_H6);
+    }
+} 
+
+int BME::init()
+{
+    char cmd[2];
+    cmd[0] = 0xE0;      // reset reg
+    cmd[1] = 0xB6;
+    bme.write(address, cmd, 2);
+    if(chipID()){
+        initialize();
+        return chip_id;
+        }
+        else return 0;            
+}
+
+int BME::chipID()
+{
+    char cmd[1];
+    cmd[0] = 0xD0;      // chip_id
+    bme.write(address, cmd, 1);
+    cmd[0] = 0x00;
+    bme.read(address, cmd, 1);
+    chip_id = cmd[0];
+    return chip_id;
+}
+
+float BME::getTemperature()
+{
+    if(!chipID()){init();}     // check if live sensor
+        
+    int32_t var1, var2, T, adc_T;
+    float temp;
+    char cmd[4];
+    cmd[0] = 0xFA;      // temp_msb
+    bme.write(address, cmd, 1);
+    bme.read(address, &cmd[1], 3);
+    
+    adc_T = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
+        
+    var1  = ((((adc_T>>3) - ((int32_t)dig_T1 <<1))) *
+       ((int32_t)dig_T2)) >> 11;    
+    var2  = (((((adc_T>>4) - ((int32_t)dig_T1)) *
+         ((adc_T>>4) - ((int32_t)dig_T1))) >> 12) *
+       ((int32_t)dig_T3)) >> 14;    
+    t_fine = var1 + var2;    
+    T  = (t_fine * 5 + 128) >> 8;
+    temp = T/100.0;    
+    if(temp>-41 && temp<86){    // return temperature if within device limits.
+        return temp;
+        }
+        else return 99.99;      // error value     
+}
+ 
+float BME::getPressure()
+{
+    if(!chipID()){init();}     // check if live sensor
+    
+    uint32_t adc_P;
+    int64_t var1, var2, p;
+    float press;
+    char cmd[4]; 
+    cmd[0] = 0xF7;      // press_msb
+    bme.write(address, cmd, 1);
+    bme.read(address, &cmd[1], 3);
+     
+    adc_P = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
+     
+    var1 = ((int64_t)t_fine) - 128000;
+    var2 = var1 * var1 * (int64_t)dig_P6;
+    var2 = var2 + ((var1 * (int64_t)dig_P5) << 17);
+    var2 = var2 + (((int64_t)dig_P4) << 35);
+    var1 = ((var1 * var1 * (int64_t)dig_P3)>>8)+((var1 * (int64_t)dig_P2)<<12);
+    var1 = (((((int64_t)1)<<47)+var1)) * ((int64_t)dig_P1)>>33;
+    if (var1 == 0) {return 0;}
+    p = 1048576-adc_P;
+    p = (((p<<31)-var2)*3125)/var1;
+    var1 = (((int64_t)dig_P9) * (p>>13) * (p>>13))>>25;
+    var2 = (((int64_t)dig_P8) * p)>>19;
+    p = ((p + var1 + var2)>>8) + (((int64_t)dig_P7)<<4);    
+    press = ((float)p/256)/100.0f;    
+    if(press>300 && press<1100){    // return temperature if within device limits.
+        return press;
+        }
+        else return 9999;           // error value
+}
+ 
+float BME::getHumidity()
+{
+    if(!chipID()){init();}         // check if live sensor
+    
+    uint32_t humid_raw;
+    int32_t v_x1r;
+    float humid;
+    char cmd[4]; 
+    cmd[0] = 0xfd; // hum_msb
+    bme.write(address, cmd, 1);
+    bme.read(address, &cmd[1], 2);
+ 
+    humid_raw = (cmd[1] << 8) | cmd[2];
+ 
+    v_x1r = (t_fine - 76800);
+    v_x1r = (((((humid_raw << 14) -(((int32_t)dig_H4) << 20) - (((int32_t)dig_H5) *
+            v_x1r)) + ((int32_t)16384)) >> 15) * (((((((v_x1r *
+            (int32_t)dig_H6) >> 10) * (((v_x1r * ((int32_t)dig_H3)) >> 11) +
+            32768)) >> 10) + 2097152) * (int32_t)dig_H2 + 8192) >> 14));
+    v_x1r = (v_x1r - (((((v_x1r >> 15) * (v_x1r >> 15)) >> 7) *
+            (int32_t)dig_H1) >> 4));
+    v_x1r = (v_x1r < 0 ? 0 : v_x1r);
+    v_x1r = (v_x1r > 419430400 ? 419430400 : v_x1r);
+ 
+    humid = ((float)(v_x1r >> 12))/1024.0f;
+ 
+    return humid;
+}