Differences

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--- embedded:adventures:rcservo [2016/03/01 12:41] – terrabots
+++ embedded:adventures:rcservo [2024/08/20 21:38] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+===== RC Servomotor Control =====
+RC servomotors use a form of [[http://www.endurance-rc.com/ppmtut.php|PPM]] (pulse position signaling) signalling to communicate the desired motor angle.  PPM itself is an instance of PWM (pulse width modulation) signalling where the pulse high time has specific meaning. Furthermore, there is usually a minimum low time at the start of the signal frame so that the receiving end can reset itself and decode the new command.
+Most of the modern embedded controller programming IDEs now have a library for performing this task.  That makes it super easy to control servo-motors, unless you want to control more than the chip can provide (in terms of PWM/PPM signal lines).  In that case, specialized methods are needed to enhance the functionality of the microprocessor to do more than the libraries are coded to do. Essentially, you'd be coding up your own library.
+Part of getting these servo-motors to work involves calibration. Even though they can be commanded, the problem is that each microcontroller and programming interface has its own numerical range for the command specification.  Furthermore, it doesn't always align with the angular range of the servomotor itself.  Thus, there needs to be a step that measures the angles associated to different command values across the legal range, then fits a line to the data acting as though the angle were the input and the associated command value were the output.  A serviceable example of this is the [[ece4560:piktul:calibrate|calibration interface for the piktul robot]].
+==== Arduino RC Servomotor Control ====
+To be done.
+==== TI RC Servomotor Control ====
+To be done.
+==== mBed RC Servomotor Control ===
 Controlling a servo via the mBed requires you to
   * Write code like that shown below to control it via internal and/or external input - see below for example code
-  * Use an optoisolator chip to eliminate signal problems due to the differences in the voltage level from the mBed (3.3V) and the power supply (likely around 5.0V) - see the Bridging Power Supplies page for information
+  * Use an optoisolator chip to eliminate signal problems due to the differences in the voltage level from the mBed (3.3V) and the power supply (likely around 5.0V) - see the [[embedded:adventures:dualpower|Bridging Power Supplies page]] for information
 {{:embedded:adventures:screen_shot_2016-03-01_at_12.31.06_pm.png?600|}}