Refs #3364. Build ok. Not tested.

Author: Javier Moreno

actuator/COLCON_IGNORE

@@ -1,23 +1,24 @@
 #include <rclc/rclc.h>
-#include <std_msgs/msg/String.h>
-#include <std_msgs/msg/Float64.h>
+#include <std_msgs/msg/string.h>
+#include <std_msgs/msg/float64.h>
 
 #include <stdio.h>
 
+rclc_publisher_t* publisher;
+
+
 void on_message(const void* msgin)
 {
     const std_msgs__msg__Float64* msg = (const std_msgs__msg__Float64*)msgin;
 
-
-    printf("I heard: [%i]\n", msg->data);
-
-
     // Publish warning if value is less than 1000 
     if (msg->data <= 1000)
     {
         std_msgs__msg__String Warning;
-        Warning.data = "Warning"; 
-            
+        Warning.data.data = "Warning"; 
+        Warning.data.size = strlen(Warning.data.data); 
+        Warning.data.capacity = strlen(Warning.data.data); 
+          
         rclc_publish(publisher, (const void*)&Warning);
     }
 
@@ -30,7 +31,7 @@ int main(int argc, char* argv[])
     rclc_init(0, NULL);
     rclc_node_t* node        = rclc_create_node("actuator", "");
     rclc_subscription_t* sub = rclc_create_subscription(node, RCLC_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Float64), "position_sensor", on_message, 1, false);
-    rclc_publisher_t* publisher = rclc_create_publisher(node, RCLC_GET_MSG_TYPE_SUPPORT(std_msgs, msg, String), "Warning", 1);
+    publisher = rclc_create_publisher(node, RCLC_GET_MSG_TYPE_SUPPORT(std_msgs, msg, String), "Warning", 1);
 
     rclc_spin_node(node);
 

actuator/main.c

@@ -4,7 +4,7 @@ project(display)
 
 find_package(ament_cmake REQUIRED)
 find_package(rclc REQUIRED)
-find_package(display REQUIRED)
+find_package(std_msgs REQUIRED)
 
 add_executable(display main.c)
 ament_target_dependencies(display rclc std_msgs)

display/CMakeLists.txt

@@ -1,35 +1,32 @@
 #include <rclc/rclc.h>
-#include <std_msgs/msg/float64.h>
+#include <std_msgs/msg/string.h>
 
 #include <stdio.h>
-#include <math.h>
-#include <time.h>
+
+static unsigned WaringCount = 0;
+
+void on_message(const void* msgin)
+{
+    const std_msgs__msg__String* msg = (const std_msgs__msg__String*)msgin;
+
+
+    printf("[%i] %s\n", WaringCount++, msg->data.data);
+}
+
 
 int main(int argc, char *argv[])
 {
     (void)argc;
     (void)argv;
+
     rclc_init(0, NULL);
-    rclc_node_t* node     = rclc_create_node("display", "");
-    rclc_publisher_t* publisher = rclc_create_publisher(node, RCLC_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Float64), "position_sensor", 1);
-
-    std_msgs__msg__Float64 msg;
-    msg.data = 0;
-    double Count = 0;
-    srand((unsigned) time(&t));
-
-    while (rclc_ok())
-    {
-        // Emulate senoidal change position 2000 to 0
-        Count += 0.1;
-        msg.data = 1000* sin(Count) + 1000; 
-            
-        rclc_publish(publisher, (const void*)&msg);
-        rclc_spin_node_once(node, (rand() % 900 + 100));
-    }
-
-    if (publisher) rclc_destroy_publisher(publisher);
-    if (node) rclc_destroy_node(node);
 
-    return 0;
+    rclc_node_t* node        = rclc_create_node("display", "");
+    rclc_subscription_t* sub = rclc_create_subscription(node, RCLC_GET_MSG_TYPE_SUPPORT(std_msgs, msg, String), "Warning", on_message, 1, false);
+
+    rclc_spin_node(node);
+
+    if (sub) rclc_destroy_subscription(sub);
+    if (node) rclc_destroy_node(node);
+
 }

display/COLCON_IGNORE

@@ -9,6 +9,8 @@ find_package(std_msgs REQUIRED)
 add_executable(position_sensor main.c)
 ament_target_dependencies(position_sensor rclc std_msgs)
 
+target_link_libraries(position_sensor m)
+
 install(TARGETS
   position_sensor
   DESTINATION lib/${PROJECT_NAME}

display/main.c

@@ -16,6 +16,7 @@ int main(int argc, char *argv[])
     std_msgs__msg__Float64 msg;
     msg.data = 0;
     double Count = 0;
+    time_t t;
     srand((unsigned) time(&t));
 
     while (rclc_ok())