diff --git a/README.md b/README.md
index 43e65d8..221d9c4 100644
--- a/README.md
+++ b/README.md
@@ -62,5 +62,17 @@ docker exec -it ggcs-rosbridge /bin/bash -c \
 ```bash
 docker exec -it ggcs-rosbridge /bin/bash -c \
   'source /opt/ros/humble/setup.bash && \
-   ros2 topic pub /gps sensor_msgs/msg/NavSatFix "{latitude: 36.000, longitude: 42.000}"'
+   ros2 topic pub /roll std_msgs/msg/Float64 "{data: 30.0}"'
+```
+
+```bash
+docker exec -it ggcs-rosbridge /bin/bash -c \
+  'source /opt/ros/humble/setup.bash && \
+   ros2 topic pub /pitch std_msgs/msg/Float64 "{data: 30.0}"'
+```
+
+```bash
+docker exec -it ggcs-rosbridge /bin/bash -c \
+  'source /opt/ros/humble/setup.bash && \
+   ros2 topic pub /gps sensor_msgs/msg/NavSatFix "{latitude: 36.000, longitude: 42.000, altitude: 10.5}"'
 ```
diff --git a/src/config.ts b/src/config.ts
index c580330..f4f2ea1 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -25,11 +25,6 @@ const targetSpeedTopic: Topic = {
   type: "std_msgs/msg/Float64"
 }
 
-const altitudeTopic: Topic = {
-  name: "/altitude",
-  type: "std_msgs/msg/Float64"
-};
-
 const accelTopic: Topic = {
   name: "/accel",
   type: "std_msgs/msg/Float64"
@@ -65,8 +60,8 @@ const hudWidget: Widget = {
     },
     altitude: {
       type: "subscriber",
-      topic: altitudeTopic,
-      topicField: ".data"
+      topic: gpsTopic,
+      topicField: ".altitude"
     }
   }
 };
@@ -178,6 +173,7 @@ export const config: Entity = {
                         setSpeed: {
                           type: "publisher",
                           topic: targetSpeedTopic,
+                          topicField: ".data"
                         },
                         targetSpeed: {
                           type: "subscriber",
diff --git a/src/interfaces.ts b/src/interfaces.ts
index c110b42..9ab9fe7 100644
--- a/src/interfaces.ts
+++ b/src/interfaces.ts
@@ -41,6 +41,7 @@ export interface ConstantValue {
 export interface PublisherValue {
   type: typeof ValueTypes.publisher;
   topic: Topic;
+  topicField?: string;
 }
 
 export type Value = SubscriberValue | ServiceValue | ConstantValue | PublisherValue;
diff --git a/src/middleware/binders/publishers.ts b/src/middleware/binders/publishers.ts
index 9926071..2c77f23 100644
--- a/src/middleware/binders/publishers.ts
+++ b/src/middleware/binders/publishers.ts
@@ -8,15 +8,32 @@ export type PublisherBinding = {
   instanceId: string;
   attrName: string;
   topic: Topic;
+  topicField?: string;        // optional dot-path like ".data"
 };
 
+function setByPath(target: any, dotPath: string, value: any) {
+  const parts = dotPath.replace(/^\./, "").split(".").filter(Boolean);
+  let cur = target;
+  for (let i = 0; i < parts.length; i++) {
+    const p = parts[i];
+    const isLast = i === parts.length - 1;
+    if (isLast) {
+      cur[p] = value;
+    } else {
+      cur[p] = cur[p] ?? {};
+      cur = cur[p];
+    }
+  }
+}
+
 export function collectPublisherBindings(config: unknown): PublisherBinding[] {
   return collectBindings<PublisherBinding>(
     config,
     (e) => e.type === ValueTypes.publisher && isObject(e.topic),
     ({ instanceId, attrName, entry }) => {
       const topic = entry.topic as Topic;
-      return { instanceId, attrName, topic };
+      const topicField = typeof (entry as any).topicField === "string" ? String((entry as any).topicField) : undefined;
+      return { instanceId, attrName, topic, topicField };
     }
   );
 }
@@ -27,13 +44,36 @@ export function attachPublisherBindings(bindings?: PublisherBinding[]) {
   const disposers: Array<() => void> = [];
 
   for (const b of list) {
-    console.log("attachPublisherBindings", b);
     const pub = sharedTopics.getPublisher({ name: b.topic.name, type: b.topic.type });
-    const unregister = publisherBus.register(b.instanceId, b.attrName, (msg: any) => {
+
+    // Expose function: accepts primitive or full message.
+    const unregister = publisherBus.register(b.instanceId, b.attrName, (input: any) => {
       try {
+        let msg: any = input;
+        if (b.topicField) {
+          if (input !== null && typeof input === "object") {
+            // If field missing, set it with the whole input (common case: user passes primitive -> not here)
+            const parts = b.topicField.replace(/^\./, "").split(".").filter(Boolean);
+            let cur = msg, missing = false;
+            for (let i = 0; i < parts.length; i++) {
+              const p = parts[i];
+              const isLast = i === parts.length - 1;
+              if (!(p in cur)) {
+                missing = true;
+                if (!isLast) cur[p] = {};
+              }
+              if (isLast) break;
+              cur = cur[p];
+            }
+            if (missing) setByPath(msg, b.topicField, input);
+          } else {
+            // Primitive or non-object: wrap into an object via topicField
+            msg = {};
+            setByPath(msg, b.topicField, input);
+          }
+        }
         pub.publish(msg);
-      } catch {
-      }
+      } catch {}
     });
 
     disposers.push(() => {
diff --git a/src/widgets/SampleWidget.tsx b/src/widgets/SampleWidget.tsx
index 0c34e12..e597e37 100644
--- a/src/widgets/SampleWidget.tsx
+++ b/src/widgets/SampleWidget.tsx
@@ -23,7 +23,9 @@ export function SampleWidget({ speedLabel }: Props) {
   const publishSpeed = () => {
     const v = Number(targetSpeed);
     if (!Number.isFinite(v)) return;
-    publishSetSpeed({ data: v });
+    // Middleware now supports topicField mapping, so send primitive
+    publishSetSpeed(v);
+    // publishSetSpeed({ data: v });  // This is also valid
   };
 
   let _speed: string = "—";