====== SimpleSoftwareServo ======
by Tyler Bletsch (Tyler.Bletsch AT gmail.com)

SimpleSoftwareServo is an [[http://arduino.cc|Arduino]] library; it drives servos on any number of pins at once.  Same API as the default servo library, except you need to call SimpleSoftwareServo::refresh() each time you want to send a pulse (at least every 20ms, preferably).

===== Download =====
[[http://dsss.be/f/dat/SimpleSoftwareServo.zip|Download SimpleSoftwareServo v0.1]]


===== Requirements =====

  * Arduino-compatible microcontroller running at ≥ 8 MHz
  * If using an ATtiny, you need an Arduino specification file and programmer that can get to it ([[http://hlt.media.mit.edu/?p=1695|details]]).
  * The user must call refresh() each time a pulse needs to be generated

===== Installation =====

  * Extract to the 'libraries' directory under your sketchbook directory.

===== Background =====

Based on [[http://playground.arduino.cc/ComponentLib/servo|SoftwareServo]] with pieces from [[http://www.cunningturtle.com/servo8bit-library-version-0-6-released/|Servo8Bit by CunningTurtle]].

This is a replacement for SoftwareServo, which was great for ATtiny controllers,
except for two problems:
  - It didn't include "Arduino.h", so it didn't compile (?)
  - It played pretty loose with the inter-pulse time, waiting until AFTER 20ms to pulse again, so if you had a delay of 15ms before the refresh, you'd wait 15+15=30ms plus computation time between pulses, which is fine for servos, but might upset the motor controller I'm using.

So I took it and rewrote the refresh method and a few other things to 
standardize the pulse-to-pulse time rather than the inter-pulse time.
Now the output on my oscilloscope is gorgeous.

It's nearly a drop-in replacement for SoftwareServo, but be aware:
It will generate a pulse EVERY time refresh is called, unlike SoftwareServo,
which would ignore calls that were too close together. This may change
behavior in some cases.  I prefer this behavior, because it avoids
uneven pulse timing.

===== Links =====
  * [[http://hlt.media.mit.edu/?p=1695|How to use ATtiny MCUs with Arduino]]
    * Note: instead of the capacitor they show, you can just jam a wire between RESET and 5V.
  * [[http://playground.arduino.cc/ComponentLib/servo|SoftwareServo]]
  * [[http://www.cunningturtle.com/servo8bit-library-version-0-6-released/|Servo8Bit by CunningTurtle]].

===== Example usage =====
{{youtube>ai3KY5z6Kgc}}

<code=c>
#include <SimpleSoftwareServo.h>

/*
 * Move a servo based on input from a knob.  Also set brightness of an LED proportional to servo angle.
 */

SimpleSoftwareServo servo1;

int servo1_pin = 2;
int led_pin = 0;
int pot_pin = 2;  // analog input pin (different numbering scheme from digital pins)

void setup() {
  pinMode(led_pin, OUTPUT);
  servo1.attach(servo1_pin);
}

void loop() {
  int val = analogRead(pot_pin);
  servo1.write(map(val,0,1023,0,180));
  analogWrite(led_pin,map(val,0,1023,0,255));
  delay(15); // optional, since refresh() will delay as needed for the next pulse
  SimpleSoftwareServo::refresh();
}

</code>