address https://github.com/adafruit/Adafruit_Sensor/issues/48

Adafruit_Sensor.cpp

@@ -97,6 +97,9 @@ void Adafruit_Sensor::printSensorDetails(void) {
   case SENSOR_TYPE_GAS_RESISTANCE:
     Serial.print(F("Gas Resistance (ohms)"));
     break;
+  case SENSOR_TYPE_UNITLESS_PERCENT:
+    Serial.print(F("Unitless Percent (%)"));
+    break;
   }
 
   Serial.println();

Adafruit_Sensor.h

@@ -79,6 +79,8 @@ typedef enum {
   SENSOR_TYPE_PM25_ENV = (27),
   SENSOR_TYPE_PM100_ENV = (28),
   SENSOR_TYPE_GAS_RESISTANCE = (29),
+  SENSOR_TYPE_LUX = (30),
+  SENSOR_TYPE_UNITLESS_PERCENT = (31)
 } sensors_type_t;
 
 /** struct sensors_vec_s is used to return a vector in a common format. */
@@ -132,7 +134,7 @@ typedef struct {
   int32_t reserved0; /**< reserved */
   int32_t timestamp; /**< time is in milliseconds */
   union {
-    float data[4];              ///< Raw data
+    float data[4];              ///< Raw data */
     sensors_vec_t acceleration; /**< acceleration values are in meter per second
                                    per second (m/s^2) */
     sensors_vec_t
@@ -168,6 +170,8 @@ typedef struct {
                         million (ppm) */
     float gas_resistance;   /**< Proportional to the amount of VOC particles in
                                the air (Ohms) */
+    float lux;              /**< SI lux (Lux) */
+    float unitless_percent; /**<Percentage, unit-less (%) */
     sensors_color_t color;  /**< color in RGB component values */
   };                        ///< Union for the wide ranges of data we can carry
 } sensors_event_t;

README.md

@@ -161,6 +161,7 @@ typedef struct
         float           pm25_env,
         float           pm100_env,
         float           gas_resistance,
+        float           unitless_percent,
         sensors_color_t color;
     };
 } sensors_event_t;
@@ -189,7 +190,7 @@ Calling this function will provide some basic information about the sensor (the
 
 ## Standardised SI values for `sensors_event_t`
 
-A key part of the abstraction layer is the standardisation of values on SI units of a particular scale, which is accomplished via the data[4] union in sensors\_event\_t above.  This 16 byte union includes fields for each main sensor type, and uses the following SI units and scales:
+A key part of the abstraction layer is the standardization of values on SI units of a particular scale, which is accomplished via the data[4] union in sensors\_event\_t above.  This 16 byte union includes fields for each main sensor type, and uses the following SI units and scales:
 
 - **acceleration**: values are in **meter per second per second** (m/s^2)
 - **magnetic**: values are in **micro-Tesla** (uT)
@@ -215,12 +216,13 @@ A key part of the abstraction layer is the standardisation of values on SI units
 - **pm25_env**: values are in **parts per million** (ppm)
 - **pm100_env**: values are in **parts per million** (ppm)
 - **gas_resistance**: values are in **ohms**
+- **unitless_percent**: values are in **%**
 
 ## The Unified Driver Abstraction Layer in Practice ##
 
 Using the unified sensor abstraction layer is relatively easy once a compliant driver has been created.
 
-Every compliant sensor can now be read using a single, well-known 'type' (sensors\_event\_t), and there is a standardised way of interrogating a sensor about its specific capabilities (via sensor\_t).
+Every compliant sensor can now be read using a single, well-known 'type' (sensors\_event\_t), and there is a standardized way of interrogating a sensor about its specific capabilities (via sensor\_t).
 
 An example of reading the [TSL2561](https://github.com/adafruit/Adafruit_TSL2561) light sensor can be seen below: