- small corrections

- changes to use the same source code with ESP8266 (esp-open-rtos) and
  ESP32 (ESP-IDF)

extras/ccs811/ccs811.c

@@ -1,14 +1,16 @@
 /*
- * Driver for ams CCS811 digital temperature, humity, pressure and
- * gas sensor connected to I2C or SPI
+ * Driver for AMS CCS811 digital gas sensor connected to I2C.
  *
- * Part of esp-open-rtos [https://github.com/SuperHouse/esp-open-rtos]
+ * This driver is for the usage with the ESP8266 and FreeRTOS (esp-open-rtos)
+ * [https://github.com/SuperHouse/esp-open-rtos]. It is also working with ESP32
+ * and ESP-IDF [https://github.com/espressif/esp-idf.git] as well as Linux
+ * based systems using a wrapper library for ESP8266 functions.
  *
  * ---------------------------------------------------------------------------
  *
  * The BSD License (3-clause license)
  *
- * Copyright (c) 2017 Gunar Schorcht (https://github.com/gschorcht]
+ * Copyright (c) 2017 Gunar Schorcht (https://github.com/gschorcht)
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -39,14 +41,7 @@
  */
 
 #include <string.h>
-
-#include "espressif/esp_common.h"
-#include "espressif/sdk_private.h"
-
-#include "FreeRTOS.h"
-#include "task.h"
-
-#include "i2c/i2c.h"
+#include <stdlib.h>
 
 #include "ccs811.h"
 
@@ -239,7 +234,7 @@ bool ccs811_set_mode (ccs811_sensor_t* dev, ccs811_mode_t mode)
     
     // check whether setting measurement mode were succesfull
     if (!ccs811_reg_read(dev, CCS811_REG_MEAS_MODE, (uint8_t*)&reg, 1) ||
-        !reg.drive_mode == mode)
+        reg.drive_mode != mode)
     {
         error_dev ("Could not set measurement mode to %d", __FUNCTION__, dev, mode);
         return ccs811_check_error_status (dev);