From 9a45c2babccb89b11c20b9b6172f5e8c10f1e8b8 Mon Sep 17 00:00:00 2001
From: "DrZiplok@gmail.com"
 <DrZiplok@gmail.com@f9c3cf11-9bcb-44bc-f272-b75c42450872>
Date: Fri, 26 Nov 2010 04:36:43 +0000
Subject: [PATCH] Re-type delta t, explicitly size error args to get_pid.

git-svn-id: https://arducopter.googlecode.com/svn/trunk@936 f9c3cf11-9bcb-44bc-f272-b75c42450872
---
 libraries/PID/PID.cpp |  2 +-
 libraries/PID/PID.h   | 19 +++++++++++--------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/libraries/PID/PID.cpp b/libraries/PID/PID.cpp
index b64d3984cd..8eb65da747 100644
--- a/libraries/PID/PID.cpp
+++ b/libraries/PID/PID.cpp
@@ -9,7 +9,7 @@
 #include "PID.h"
 
 long
-PID::get_pid(long error, long dt, float scaler)
+PID::get_pid(int32_t error, uint16_t dt, float scaler)
 {
 	float output		= 0;
  	float delta_time	= (float)dt / 1000;
diff --git a/libraries/PID/PID.h b/libraries/PID/PID.h
index 5adb8c11a8..f9425c80b3 100644
--- a/libraries/PID/PID.h
+++ b/libraries/PID/PID.h
@@ -44,13 +44,16 @@ public:
 	///
 	/// Positive error produces positive output.
 	///
-	/// @param err		The measured error value
-	/// @param dt		The time delta in milliseconds
+	/// @param error	The measured error value
+	/// @param dt		The time delta in milliseconds (note
+	///					that update interval cannot be more
+	///					than 65.535 seconds due to limited range
+	///					of the data type).
 	/// @param scaler	An arbitrary scale factor
 	///
 	/// @returns		The updated control output.
 	///
-	long 	get_pid(long err, long dt, float scaler=1);
+	long 	get_pid(int32_t error, uint16_t dt, float scaler = 1.0);
 
 	/// Reset the PID integrator
 	///
@@ -94,11 +97,11 @@ private:
 	int32_t		_last_error;	///< last error for derivative
 	float		_last_derivative; ///< last derivative for low-pass filter
 
-	/// low pass filter cut frequency
-	/// for derivative calculation,
-	/// set to 20 Hz becasue anything over that
-	/// is probably noise, see
-	/// http://en.wikipedia.org/wiki/Low-pass_filter
+	/// Low pass filter cut frequency for derivative calculation.
+	///
+	/// 20 Hz becasue anything over that is probably noise, see
+	/// http://en.wikipedia.org/wiki/Low-pass_filter.
+	///
 	static const uint8_t _RC = 20; 
 };