From 9abc8e26b789af0ef132c5c38e3d8ada821c3657 Mon Sep 17 00:00:00 2001
From: Thomas Gubler <thomasgubler@gmail.com>
Date: Fri, 28 Nov 2014 16:30:12 +0100
Subject: [PATCH] correctly handle interval, call callback only when topic
 updated, add example for 2 topics

---
 src/examples/subscriber/subscriber.cpp | 11 ++++++-----
 src/platforms/px4_nodehandle.h         |  2 +-
 src/platforms/px4_subscriber.h         |  5 +++++
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/examples/subscriber/subscriber.cpp b/src/examples/subscriber/subscriber.cpp
index ed0635f180..a186ba94a7 100644
--- a/src/examples/subscriber/subscriber.cpp
+++ b/src/examples/subscriber/subscriber.cpp
@@ -36,10 +36,10 @@ void rc_channels_callback(const PX4_TOPIC_T(rc_channels) &msg)
 {
 	PX4_INFO("I heard: [%llu]", msg.timestamp_last_valid);
 }
-// void rc_channels_callback(int i)
-// {
-	// PX4_INFO("I heard: [%d]", i);
-// }
+void rc_channels_callback2(const PX4_TOPIC_T(rc_channels) &msg)
+{
+	PX4_INFO("I heard2: [%llu]", msg.timestamp_last_valid);
+}
 namespace px4
 {
 bool task_should_exit = false;
@@ -81,7 +81,8 @@ PX4_MAIN_FUNCTION(subscriber)
 	 * is the number of messages that will be buffered up before beginning to throw
 	 * away the oldest ones.
 	 */
-	PX4_SUBSCRIBE(n, rc_channels, rc_channels_callback, 1000);
+	PX4_SUBSCRIBE(n, rc_channels, rc_channels_callback, 100);
+	PX4_SUBSCRIBE(n, rc_channels, rc_channels_callback2, 1000);
 	PX4_INFO("subscribed");
 
 	/**
diff --git a/src/platforms/px4_nodehandle.h b/src/platforms/px4_nodehandle.h
index eb90590e41..45ef225fa6 100644
--- a/src/platforms/px4_nodehandle.h
+++ b/src/platforms/px4_nodehandle.h
@@ -114,7 +114,7 @@ public:
 		SubscriberPX4<M> *sub_px4 = new SubscriberPX4<M>(meta, interval, callback, &_subs);
 
 		/* Check if this is the smallest interval so far and update _sub_min_interval */
-		if (_sub_min_interval == nullptr || _sub_min_interval->getInterval() < sub_px4->getInterval()) {
+		if (_sub_min_interval == nullptr || _sub_min_interval->getInterval() > sub_px4->getInterval()) {
 			_sub_min_interval = sub_px4;
 		}
 		return (Subscriber*)sub_px4;
diff --git a/src/platforms/px4_subscriber.h b/src/platforms/px4_subscriber.h
index efec8f2a39..6e0ef8aed6 100644
--- a/src/platforms/px4_subscriber.h
+++ b/src/platforms/px4_subscriber.h
@@ -89,6 +89,11 @@ public:
 	~SubscriberPX4() {};
 
 	void update() {
+		if (!uORB::Subscription<M>::updated()) {
+			/* Topic not updated, do not call callback */
+			return;
+		}
+
 		/* get latest data */
 		uORB::Subscription<M>::update();