From a30df926fd1e041cc9059e94f0f9a1cba1acf9f5 Mon Sep 17 00:00:00 2001
From: Frank Paynter <paynterf@gmail.com>
Date: Sat, 15 May 2021 15:32:31 -0400
Subject: [PATCH] Updated README.txt to include information about synching PID
 engine to external timing sources

---
 README.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/README.txt b/README.txt
index 3f2fb63..ab13b04 100644
--- a/README.txt
+++ b/README.txt
@@ -9,3 +9,7 @@
    http://brettbeauregard.com/blog/2011/04/improving-the-beginners-pid-introduction/
 
  - For function documentation see:  http://playground.arduino.cc/Code/PIDLibrary
+
+ - To synchronize PID::Compute with an external timing source such as a TIMER ISR, 
+	call SetSampleTime() with an argument of zero. This will force Compute to generate a
+	new output value each time it is called.