CCS811 driver added (#479)

examples/ccs811/ccs811_plus_sht3x/Makefile

@@ -0,0 +1,3 @@
+PROGRAM=CCS811_Plus_SHT3x
+EXTRA_COMPONENTS = extras/i2c extras/ccs811 extras/sht3x
+include ../../../common.mk

examples/ccs811/ccs811_plus_sht3x/ccs811_plus_sht3x.c

@@ -0,0 +1,106 @@
+/**
+ * Simple example with one CCS811 sensor connected to I2C bus 0 and one SHT3x
+ * sensor to determine ambient temperature. New data are fetched peridically.
+ *
+ * Harware configuration:
+ *
+ * +------------------------+       +--------+
+ * | ESP8266  Bus 0         |       | CCS811 |
+ * |          GPIO 5 (SCL)  >--+----> SCL    |
+ * |          GPIO 4 (SDA)  ---|-+--- SDA    |
+ * |          GND           ---|-|--> /WAKE  |
+ * |                        |  | |  +--------+
+ * |                        |  | |  | SHT3x  |
+ * |                        |  +----> SCL    |
+ * |                        |    +--- SDA    |
+ * +------------------------+       +--------+
+ */
+
+#include "espressif/esp_common.h"
+#include "esp/uart.h"
+#include "i2c/i2c.h"
+
+#include "FreeRTOS.h"
+#include <task.h>
+
+// include CCS811 driver
+#include "ccs811/ccs811.h"
+
+// include SHT3x driver
+#include "sht3x/sht3x.h"
+
+// define I2C interfaces at which CCS811 and SHT3x sensors are connected
+#define I2C_BUS       0
+#define I2C_SCL_PIN   5
+#define I2C_SDA_PIN   4
+
+static ccs811_sensor_t* ccs811; // CCS811 device data structure
+static sht3x_sensor_t*  sht3x;  // SHT3x device data structure
+
+/*
+ * User task that fetches the sensor values every 2 seconds.
+ */
+void user_task(void *pvParameters)
+{
+    uint16_t tvoc;
+    uint16_t eco2;
+
+    float    temperature;
+    float    humidity;
+
+    // start periodic measurement with 1 measurement per second
+    ccs811_set_mode (ccs811, ccs811_mode_1s);
+
+    // start periodic measurements with 1 measurement per second
+    sht3x_start_measurement (sht3x, sht3x_periodic_1mps, sht3x_high);
+
+    // passive waiting until measurement results are available
+    vTaskDelay (sht3x_get_measurement_duration (sht3x_high));
+
+    TickType_t last_wakeup = xTaskGetTickCount();
+
+    while (1)
+    {
+        // get the results from CCS811 and do something with them
+        if (ccs811_get_results (ccs811, &tvoc, &eco2, 0, 0))
+            printf("%.3f CCS811 Sensor periodic: TVOC %d ppb, eCO2 %d ppm\n",
+                   (double)sdk_system_get_time()*1e-3, tvoc, eco2);
+
+        // get the values from SHT3x and do something with them
+        if (sht3x_get_results (sht3x, &temperature, &humidity))
+        {
+            printf("%.3f SHT3x Sensor: %.2f °C, %.2f %%\n",
+                   (double)sdk_system_get_time()*1e-3, temperature, humidity);
+
+            // set CCS811 environmental data with values fetched from SHT3x
+            ccs811_set_environmental_data (ccs811, temperature, humidity);
+        }
+        // passive waiting until 2 seconds is 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 CCS811 sensors are connected
+    i2c_init(I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ_100K);
+
+    // longer clock stretching is required for CCS811
+    i2c_set_clock_stretch (I2C_BUS, CCS811_I2C_CLOCK_STRETCH);
+
+    // init the sensors
+    ccs811 = ccs811_init_sensor (I2C_BUS, CCS811_I2C_ADDRESS_1);
+    sht3x  = sht3x_init_sensor  (I2C_BUS, SHT3x_ADDR_2);
+
+    if (ccs811 && sht3x)
+        // create a task that uses the sensor
+        xTaskCreate(user_task, "user_task", 256, NULL, 2, NULL);
+}