Driver for Bosch Sensortec BME680 added

BME680 is an ulta-low-power environmental sensor that integrates
temperature, pressure, humidity and gas sensors in only one unit.

examples/bme680/bme680_two_sensors/Makefile

@@ -0,0 +1,3 @@
+PROGRAM=BME680_Tow_Sensors
+EXTRA_COMPONENTS = extras/i2c extras/bme680
+include ../../../common.mk

examples/bme680/bme680_two_sensors/bme680_two_sensors.c

@@ -0,0 +1,146 @@
+/**
+ * Simple example with two sensors, one sensor connected to I2C bus 0 and
+ * one sensor connected to SPI. It also shows both approaches for the
+ * implementation of waiting for measurement results, one as busy waiting
+ * and one as passive waiting using *vTaskDelay*.
+ *
+ * Harware configuration:
+ *
+ *   +-------------------------+     +----------+
+ *   | ESP8266  I2C Bus 0      |     | BME680_1 |
+ *   |          GPIO 5 (SCL)   ------> SCL      |
+ *   |          GPIO 4 (SDA)   ------- SDA      |
+ *   |                         |     +----------+
+ *   |          SPI Bus 1      |     | BME680_2 |
+ *   |          GPIO 12 (MISO) <------ SDO      |
+ *   |          GPIO 13 (MOSI) >-----> SDI      |
+ *   |          GPIO 14 (SCK)  >-----> SCK      |
+ *   |          GPIO 2  (CS)   >-----> CS       |
+ *   +-------------------------+     +----------+
+ */
+ 
+#include "espressif/esp_common.h"
+#include "esp/uart.h"
+
+// include communication interface driver
+#include "esp/spi.h"
+#include "i2c/i2c.h"
+
+// include BME680 driver
+#include "bme680/bme680.h"
+
+// define I2C interface for BME680 sensor 1
+#define SPI_BUS         1
+#define SPI_CS_GPIO     2   // GPIO 15, the default CS of SPI bus 1, can't be used
+// define SPI interface for BME680 sensor 2 
+#define I2C_BUS         0
+#define I2C_SCL_PIN     GPIO_ID_PIN((5))
+#define I2C_SDA_PIN     GPIO_ID_PIN((4))
+
+static bme680_sensor_t* sensor1;
+static bme680_sensor_t* sensor2;
+
+/*
+ * User task that triggers measurements of sensor1 every 5 seconds. It 
+ * uses *vTaskDelay* to wait for measurement results.
+ */
+void user_task_sensor1(void *pvParameters)
+{
+    bme680_values_float_t values;
+    int32_t duration;
+
+    TickType_t last_wakeup = xTaskGetTickCount();
+    
+    while (1) 
+    {    
+        // trigger the sensor to start one TPHG measurement cycle 
+        duration = bme680_force_measurement (sensor1);
+        
+        // passive waiting until measurement results are available
+        if (duration > 0) vTaskDelay (duration);
+        
+        // get the results and so something with them
+        if (bme680_get_results_float (sensor1, &values))
+            printf("%.3f BME680 Sensor1: %.2f °C, %.2f %%, %.2f hPa, %.2f Ohm\n",
+                   (double)sdk_system_get_time()*1e-3,
+                   values.temperature, values.humidity, 
+                   values.pressure, values.gas_resistance);
+ 
+        // passive waiting until 5 seconds are over
+        vTaskDelayUntil(&last_wakeup, 5000 / portTICK_PERIOD_MS);
+    }
+}
+
+/*
+ * User task that triggers measurements of sensor1 every 2 seconds. It 
+ * uses *vTaskDelay* to wait for measurement results.
+ */
+void user_task_sensor2(void *pvParameters)
+{
+    bme680_values_float_t values;
+
+    TickType_t last_wakeup = xTaskGetTickCount();
+    
+    while (1) 
+    {    
+        // trigger the sensor to start one TPHG measurement cycle 
+        bme680_force_measurement (sensor2);
+        
+        // busy waiting until measurement results are available
+        while (bme680_is_measuring (sensor2) > 0) ;
+
+        // get the results and so something with them
+        if (bme680_get_results_float (sensor2, &values))
+            printf("%.3f BME680 Sensor2: %.2f °C, %.2f %%, %.2f hPa, %.2f Ohm\n",
+                   (double)sdk_system_get_time()*1e-3,
+                   values.temperature, values.humidity, 
+                   values.pressure, values.gas_resistance);
+ 
+        // passive waiting until 2 seconds are over
+        vTaskDelayUntil(&last_wakeup, 2000 / portTICK_PERIOD_MS);
+    }
+}
+
+
+void user_init(void)
+{
+    // Set UART Parameter
+    uart_set_baud(0, 115200);
+    // Give the UART some time to settle
+    sdk_os_delay_us(500);
+    
+    /** -- MANDATORY PART -- */
+    
+    // Init all I2C bus interfaces at which BME680 sensors are connected
+    i2c_init(I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ_100K);
+
+    // Init the sensors connected to different I2C buses with same address
+    sensor1 = bme680_init_sensor (I2C_BUS, BME680_I2C_ADDRESS_2, 0);
+    sensor2 = bme680_init_sensor (SPI_BUS, 0, SPI_CS_GPIO);
+
+    if (sensor1 && sensor2)
+    {
+        // Create the tasks that use the sensors
+        xTaskCreate(user_task_sensor1, "user_task_sensor1", 256, NULL, 2, 0);
+        xTaskCreate(user_task_sensor2, "user_task_sensor2", 256, NULL, 2, 0);
+ 
+        // That's it.
+
+        /** -- OPTIONAL PART -- */
+    
+        // Changes the oversampling rates for both sensor to different values
+        bme680_set_oversampling_rates(sensor1, osr_1x, osr_1x, osr_1x);
+        bme680_set_oversampling_rates(sensor2, osr_16x, osr_16x, osr_16x);
+    
+        // Change the IIR filter size (default iir_size_3) for temperature and 
+        // and pressure to 7.
+        bme680_set_filter_size(sensor1, iir_size_7);
+        bme680_set_filter_size(sensor2, iir_size_7);
+
+        // Change the heaeter profile (default 20 degree Celcius for 150 ms) to
+        // 200 degree Celcius for 100 ms.
+        bme680_set_heater_profile (sensor1, 200, 100);
+        bme680_set_heater_profile (sensor2, 200, 100);
+    }
+}
+