diff --git a/core/app-framework/sensor/app/sensor_api.h b/core/app-framework/sensor/app/sensor_api.h
index 094f1108..ad6a7aa2 100644
--- a/core/app-framework/sensor/app/sensor_api.h
+++ b/core/app-framework/sensor/app/sensor_api.h
@@ -16,10 +16,10 @@ uint32
 wasm_sensor_open(const char *name, int instance);
 
 bool
-wasm_sensor_config(uint32 sensor, int interval, int bit_cfg, int delay);
+wasm_sensor_config(uint32 sensor, uint32 interval, int bit_cfg, uint32 delay);
 
 bool
-wasm_sensor_config_with_attr_container(uint32 sensor, char *buffer, int len);
+wasm_sensor_config_with_attr_container(uint32 sensor, char *buffer, uint32 len);
 
 bool
 wasm_sensor_close(uint32 sensor);
diff --git a/core/app-framework/sensor/native/runtime_sensor.c b/core/app-framework/sensor/native/runtime_sensor.c
index 2e2fed92..8222ab3c 100644
--- a/core/app-framework/sensor/native/runtime_sensor.c
+++ b/core/app-framework/sensor/native/runtime_sensor.c
@@ -9,7 +9,7 @@
 #include "bh_platform.h"
 
 static sys_sensor_t *g_sys_sensors = NULL;
-static int g_sensor_id_max = 0;
+static uint32 g_sensor_id_max = 0;
 
 static sensor_client_t *
 find_sensor_client(sys_sensor_t *sensor, unsigned int client_id,
@@ -85,8 +85,8 @@ wasm_sensor_callback(void *client, uint32 sensor_id, void *user_data)
 }
 
 bool
-wasm_sensor_config(wasm_exec_env_t exec_env, uint32 sensor, int interval,
-                   int bit_cfg, int delay)
+wasm_sensor_config(wasm_exec_env_t exec_env, uint32 sensor, uint32 interval,
+                   int bit_cfg, uint32 delay)
 {
     wasm_module_inst_t module_inst = get_module_inst(exec_env);
     attr_container_t *attr_cont;
@@ -115,9 +115,9 @@ wasm_sensor_config(wasm_exec_env_t exec_env, uint32 sensor, int interval,
 
     if (s->config != NULL) {
         attr_cont = attr_container_create("config sensor");
-        attr_container_set_int(&attr_cont, "interval", interval);
+        attr_container_set_int(&attr_cont, "interval", (int)interval);
         attr_container_set_int(&attr_cont, "bit_cfg", bit_cfg);
-        attr_container_set_int(&attr_cont, "delay", delay);
+        attr_container_set_int(&attr_cont, "delay", (int)delay);
         s->config(s, attr_cont);
         attr_container_destroy(attr_cont);
     }
@@ -138,7 +138,7 @@ wasm_sensor_open(wasm_exec_env_t exec_env, char *name, int instance)
         sensor_client_t *c;
         sys_sensor_t *s = find_sys_sensor(name, instance);
         if (s == NULL)
-            return -1;
+            return (uint32)-1;
 
         unsigned int mod_id =
             app_manager_get_module_id(Module_WASM_App, module_inst);
@@ -150,14 +150,14 @@ wasm_sensor_open(wasm_exec_env_t exec_env, char *name, int instance)
         if (c) {
             // the app already opened this sensor
             os_mutex_unlock(&s->lock);
-            return -1;
+            return (uint32)-1;
         }
 
         sensor_client_t *client =
             (sensor_client_t *)wasm_runtime_malloc(sizeof(sensor_client_t));
         if (client == NULL) {
             os_mutex_unlock(&s->lock);
-            return -1;
+            return (uint32)-1;
         }
 
         memset(client, 0, sizeof(sensor_client_t));
@@ -176,7 +176,7 @@ wasm_sensor_open(wasm_exec_env_t exec_env, char *name, int instance)
         return s->sensor_id;
     }
 
-    return -1;
+    return (uint32)-1;
 }
 
 bool
@@ -294,7 +294,7 @@ add_sys_sensor(char *name, char *description, int instance,
     }
 
     g_sensor_id_max++;
-    if (g_sensor_id_max == -1)
+    if (g_sensor_id_max == UINT32_MAX)
         g_sensor_id_max++;
     s->sensor_id = g_sensor_id_max;
 
@@ -366,10 +366,10 @@ find_sensor_client(sys_sensor_t *sensor, unsigned int client_id,
 }
 
 // return the milliseconds to next check
-int
+uint32
 check_sensor_timers()
 {
-    int ms_to_next_check = -1;
+    uint32 ms_to_next_check = UINT32_MAX;
     uint32 now = (uint32)bh_get_tick_ms();
 
     sys_sensor_t *s = g_sys_sensors;
@@ -395,12 +395,12 @@ check_sensor_timers()
 
             s->last_read = now;
 
-            if (ms_to_next_check == -1 || (ms_to_next_check < s->read_interval))
+            if (s->read_interval < ms_to_next_check)
                 ms_to_next_check = s->read_interval;
         }
         else {
-            int remaining = s->read_interval - elpased_ms;
-            if (ms_to_next_check == -1 || (ms_to_next_check < remaining))
+            uint32 remaining = s->read_interval - elpased_ms;
+            if (remaining < ms_to_next_check)
                 ms_to_next_check = remaining;
         }
 
diff --git a/core/app-framework/sensor/native/runtime_sensor.h b/core/app-framework/sensor/native/runtime_sensor.h
index 22f625df..b7fba805 100644
--- a/core/app-framework/sensor/native/runtime_sensor.h
+++ b/core/app-framework/sensor/native/runtime_sensor.h
@@ -17,9 +17,9 @@ typedef struct _sys_sensor *sensor_obj_t;
 typedef struct _sensor_client {
     struct _sensor_client *next;
     unsigned int client_id; // the app id
-    int interval;
+    uint32 interval;
     int bit_cfg;
-    int delay;
+    uint32 delay;
     void (*client_callback)(void *client, uint32, attr_container_t *);
 } sensor_client_t;
 
@@ -54,7 +54,7 @@ void
 refresh_read_interval(sensor_obj_t sensor);
 void
 sensor_cleanup_callback(uint32 module_id);
-int
+uint32
 check_sensor_timers();
 void
 reschedule_sensor_read();
diff --git a/core/app-framework/sensor/native/sensor_mgr_ref.c b/core/app-framework/sensor/native/sensor_mgr_ref.c
index cbbc6df5..304214f4 100644
--- a/core/app-framework/sensor/native/sensor_mgr_ref.c
+++ b/core/app-framework/sensor/native/sensor_mgr_ref.c
@@ -88,8 +88,8 @@ static void
 thread_sensor_check(void *arg)
 {
     while (sensor_check_thread_run) {
-        int ms_to_expiry = check_sensor_timers();
-        if (ms_to_expiry == -1)
+        uint32 ms_to_expiry = check_sensor_timers();
+        if (ms_to_expiry == UINT32_MAX)
             ms_to_expiry = 5000;
         os_mutex_lock(&mutex);
         os_cond_reltimedwait(&cond, &mutex, ms_to_expiry * 1000);
diff --git a/core/app-framework/sensor/native/sensor_native_api.h b/core/app-framework/sensor/native/sensor_native_api.h
index 8fbaa3e8..0bbb315c 100644
--- a/core/app-framework/sensor/native/sensor_native_api.h
+++ b/core/app-framework/sensor/native/sensor_native_api.h
@@ -14,8 +14,8 @@ extern "C" {
 #endif
 
 bool
-wasm_sensor_config(wasm_exec_env_t exec_env, uint32 sensor, int interval,
-                   int bit_cfg, int delay);
+wasm_sensor_config(wasm_exec_env_t exec_env, uint32 sensor, uint32 interval,
+                   int bit_cfg, uint32 delay);
 uint32
 wasm_sensor_open(wasm_exec_env_t exec_env, char *name, int instance);
 
diff --git a/samples/simple/src/iwasm_main.c b/samples/simple/src/iwasm_main.c
index 4154874b..121671ff 100644
--- a/samples/simple/src/iwasm_main.c
+++ b/samples/simple/src/iwasm_main.c
@@ -526,8 +526,10 @@ iwasm_main(int argc, char *argv[])
 
     /* sensor framework */
     init_sensor_framework();
-    // add the sys sensor objects
-    add_sys_sensor("sensor_test", "This is a sensor for test", 0, 1000,
+    /* add the sys sensor objects */
+    add_sys_sensor("sensor_test1", "This is a sensor for test", 0, 1000,
+                   read_test_sensor, config_test_sensor);
+    add_sys_sensor("sensor_test2", "This is a sensor for test", 0, 1000,
                    read_test_sensor, config_test_sensor);
     start_sensor_framework();
 
diff --git a/samples/simple/wasm-apps/sensor.c b/samples/simple/wasm-apps/sensor.c
index d50145ff..c45ff67d 100644
--- a/samples/simple/wasm-apps/sensor.c
+++ b/samples/simple/wasm-apps/sensor.c
@@ -6,46 +6,78 @@
 #include "wasm_app.h"
 #include "wa-inc/sensor.h"
 
-static sensor_t sensor = NULL;
+static sensor_t sensor1 = NULL;
+static sensor_t sensor2 = NULL;
+static char *user_data = NULL;
 
 /* Sensor event callback*/
 void
 sensor_event_handler(sensor_t sensor, attr_container_t *event, void *user_data)
 {
-    printf("### app get sensor event\n");
-    attr_container_dump(event);
+    if (sensor == sensor1) {
+        printf("### app get sensor event from sensor1\n");
+        attr_container_dump(event);
+    }
+    else {
+        printf("### app get sensor event from sensor2\n");
+        attr_container_dump(event);
+    }
 }
 
 void
 on_init()
 {
-    char *user_data;
     attr_container_t *config;
 
     printf("### app on_init 1\n");
     /* open a sensor */
     user_data = malloc(100);
+    if (!user_data) {
+        printf("allocate memory failed\n");
+        return;
+    }
+
     printf("### app on_init 2\n");
-    sensor = sensor_open("sensor_test", 0, sensor_event_handler, user_data);
-    printf("### app on_init 3\n");
-
+    sensor1 = sensor_open("sensor_test1", 0, sensor_event_handler, user_data);
+    if (!sensor1) {
+        printf("open sensor1 failed\n");
+        return;
+    }
     /* config the sensor */
-    sensor_config(sensor, 1000, 0, 0);
-    printf("### app on_init 4\n");
+    sensor_config(sensor1, 1000, 0, 0);
 
+    printf("### app on_init 3\n");
+    sensor2 = sensor_open("sensor_test2", 0, sensor_event_handler, user_data);
+    if (!sensor2) {
+        printf("open sensor2 failed\n");
+        return;
+    }
+    /* config the sensor */
+    sensor_config(sensor2, 5000, 0, 0);
+
+    printf("### app on_init 4\n");
     /*
-     config = attr_container_create("sensor config");
-     sensor_config(sensor, config);
-     attr_container_destroy(config);
-     */
+    config = attr_container_create("sensor config");
+    sensor_config(sensor, config);
+    attr_container_destroy(config);
+    */
 }
 
 void
 on_destroy()
 {
-    if (NULL != sensor) {
-        sensor_config(sensor, 0, 0, 0);
+    if (NULL != sensor1) {
+        sensor_config(sensor1, 0, 0, 0);
     }
+
+    if (NULL != sensor2) {
+        sensor_config(sensor2, 0, 0, 0);
+    }
+
+    if (NULL != user_data) {
+        free(user_data);
+    }
+
     /* real destroy work including killing timer and closing sensor is
        accomplished in wasm app library version of on_destroy() */
 }