drivers, lsm6dsl: update test, and add README

tests/driver_lsm6dsl/README.md

+# About
+This is a manual test application for the ST LSM6DSL sensor driver.
+
+# Usage
+
+After successful initialization, the sensor reads the accelerometer, gyroscope,
+and temperature values every 500ms and prints them to the STDOUT. If device
+initialization fails the tests exits with 1, otherwise it runs forever.
+
+Note: reading sensor values may fail even on successful initialization.

tests/driver_lsm6dsl/main.c

 /*
  * Copyright (C) 2017 OTA keys S.A.
+ *               2017 HAW Hamburg
  *
  * This file is subject to the terms and conditions of the GNU Lesser
  * General Public License v2.1. See the file LICENSE in the top level
@@ -7,11 +8,16 @@
  */
 
 /**
+ * @ingroup tests
+ * @{
+ *
  * @file
  * @brief       Test application for the LSM6DSL accelerometer/gyroscope driver.
  *
  * @author      Vincent Dupont <vincent@otakeys.com>
+ * @author      Sebastian Meiling <s@mlng.net>
  *
+ * @}
  */
 
 #include <stdio.h>
@@ -20,7 +26,7 @@
 #include "lsm6dsl.h"
 #include "lsm6dsl_params.h"
 
-#define SLEEP       (100 * 1000U)
+#define SLEEP       (500UL * US_PER_MS)
 
 int main(void)
 {
@@ -29,42 +35,42 @@ int main(void)
     lsm6dsl_3d_data_t mag_value;
     lsm6dsl_3d_data_t acc_value;
 
-    puts("LSM6DSL test application\n");
+    puts("LSM6DSL test application");
     printf("Initializing LSM6DSL sensor at I2C_%i... ", lsm6dsl_params->i2c);
 
-    if (lsm6dsl_init(&dev, lsm6dsl_params) == 0) {
-        puts("[OK]\n");
-    }
-    else {
-        puts("[Failed]");
+    if (lsm6dsl_init(&dev, lsm6dsl_params) != LSM6DSL_OK) {
+        puts("[ERROR]");
         return 1;
     }
+    puts("[SUCCESS]\n");
 
     while (1) {
-        if (lsm6dsl_read_acc(&dev, &acc_value) == 0) {
+        if (lsm6dsl_read_acc(&dev, &acc_value) == LSM6DSL_OK) {
             printf("Accelerometer x: %i y: %i z: %i\n", acc_value.x,
                                                         acc_value.y,
                                                         acc_value.z);
         }
         else {
-            puts("\nFailed reading accelerometer values\n");
-        }
-        if (lsm6dsl_read_temp(&dev, &temp_value) == 0) {
-            printf("Temperature value: %i degrees\n", temp_value);
-        }
-        else {
-            puts("\nFailed reading value\n");
+            puts("[ERROR] reading accelerometer!\n");
         }
 
-        if (lsm6dsl_read_gyro(&dev, &mag_value) == 0) {
+        if (lsm6dsl_read_gyro(&dev, &mag_value) == LSM6DSL_OK) {
             printf("Gyroscope x: %i y: %i z: %i\n", mag_value.x,
                                                     mag_value.y,
                                                     mag_value.z);
         }
         else {
-            puts("\nFailed reading Gyroscope values\n");
+            puts("[ERROR] reading gyroscope!\n");
+        }
+
+        if (lsm6dsl_read_temp(&dev, &temp_value) == LSM6DSL_OK) {
+            printf("Temperature [in °C x 100]: %i \n", temp_value);
+        }
+        else {
+            puts("[ERROR] reading temperature!\n");
         }
 
+        puts("");
         xtimer_usleep(SLEEP);
     }