From fc944ff979dbbd49a57722fe2d1d2acf47312eb4 Mon Sep 17 00:00:00 2001
From: Jesse Morgan <jesse@jesterpm.net>
Date: Thu, 20 Oct 2011 22:16:19 -0700
Subject: Inital commit... halfway through the project

---
 libraries/PWMServo/PWMServo.cpp | 133 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 libraries/PWMServo/PWMServo.cpp

(limited to 'libraries/PWMServo/PWMServo.cpp')

diff --git a/libraries/PWMServo/PWMServo.cpp b/libraries/PWMServo/PWMServo.cpp
new file mode 100644
index 0000000..f80b0c8
--- /dev/null
+++ b/libraries/PWMServo/PWMServo.cpp
@@ -0,0 +1,133 @@
+#include <avr/interrupt.h>
+#include <wiring.h>
+#include <PWMServo.h>
+
+/*
+  PWMServo.h - Hardware Servo Timer Library
+  Author: Jim Studt, jim@federated.com
+  Copyright (c) 2007 David A. Mellis.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+
+uint8_t PWMServo::attached9 = 0;
+uint8_t PWMServo::attached10 = 0;
+
+void PWMServo::seizeTimer1()
+{
+  uint8_t oldSREG = SREG;
+
+  cli();
+  TCCR1A = _BV(WGM11); /* Fast PWM, ICR1 is top */
+  TCCR1B = _BV(WGM13) | _BV(WGM12) /* Fast PWM, ICR1 is top */
+  | _BV(CS11) /* div 8 clock prescaler */
+  ;
+  OCR1A = 3000;
+  OCR1B = 3000;
+  ICR1 = clockCyclesPerMicrosecond()*(20000L/8);  // 20000 uS is a bit fast for the refresh, 20ms, but 
+                                                  // it keeps us from overflowing ICR1 at 20MHz clocks
+                                                  // That "/8" at the end is the prescaler.
+#if defined(__AVR_ATmega8__)
+  TIMSK &= ~(_BV(TICIE1) | _BV(OCIE1A) | _BV(OCIE1B) | _BV(TOIE1) );
+#else
+  TIMSK1 &=  ~(_BV(OCIE1A) | _BV(OCIE1B) | _BV(TOIE1) );
+#endif
+
+  SREG = oldSREG;  // undo cli()    
+}
+
+void PWMServo::releaseTimer1() {}
+
+#define NO_ANGLE (0xff)
+
+PWMServo::PWMServo() : pin(0), angle(NO_ANGLE) {}
+
+uint8_t PWMServo::attach(int pinArg)
+{
+  return attach(pinArg, 544, 2400);
+}
+
+uint8_t PWMServo::attach(int pinArg, int min, int max)
+{
+  if (pinArg != 9 && pinArg != 10) return 0;
+  
+  min16 = min / 16;
+  max16 = max / 16;
+
+  pin = pinArg;
+  angle = NO_ANGLE;
+  digitalWrite(pin, LOW);
+  pinMode(pin, OUTPUT);
+
+  if (!attached9 && !attached10) seizeTimer1();
+
+  if (pin == 9) {
+    attached9 = 1;
+    TCCR1A = (TCCR1A & ~_BV(COM1A0)) | _BV(COM1A1);
+  }
+  
+  if (pin == 10) {
+    attached10 = 1;
+    TCCR1A = (TCCR1A & ~_BV(COM1B0)) | _BV(COM1B1);
+  }
+  return 1;
+}
+
+void PWMServo::detach()
+{
+  // muck with timer flags
+  if (pin == 9) {
+    attached9 = 0;
+    TCCR1A = TCCR1A & ~_BV(COM1A0) & ~_BV(COM1A1);
+    pinMode(pin, INPUT);
+  } 
+  
+  if (pin == 10) {
+    attached10 = 0;
+    TCCR1A = TCCR1A & ~_BV(COM1B0) & ~_BV(COM1B1);
+    pinMode(pin, INPUT);
+  }
+
+  if (!attached9 && !attached10) releaseTimer1();
+}
+
+void PWMServo::write(int angleArg)
+{
+  uint16_t p;
+
+  if (angleArg < 0) angleArg = 0;
+  if (angleArg > 180) angleArg = 180;
+  angle = angleArg;
+
+  // bleh, have to use longs to prevent overflow, could be tricky if always a 16MHz clock, but not true
+  // That 8L on the end is the TCNT1 prescaler, it will need to change if the clock's prescaler changes,
+  // but then there will likely be an overflow problem, so it will have to be handled by a human.
+  p = (min16*16L*clockCyclesPerMicrosecond() + (max16-min16)*(16L*clockCyclesPerMicrosecond())*angle/180L)/8L;
+  if (pin == 9) OCR1A = p;
+  if (pin == 10) OCR1B = p;
+}
+
+uint8_t PWMServo::read()
+{
+  return angle;
+}
+
+uint8_t PWMServo::attached()
+{
+  if (pin == 9 && attached9) return 1;
+  if (pin == 10 && attached10) return 1;
+  return 0;
+}
-- 
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