WebSVN - FlightCtrl - Diff - Rev 2117 and 2164 - /branches/dongfang_FC


#include <avr/io.h>
#include <avr/interrupt.h>
#include "eeprom.h"
#include "rc.h"
#include "attitude.h"
 
#define COARSERESOLUTION 1
 
#ifdef COARSERESOLUTION
#define NEUTRAL_PULSELENGTH 938
#define STABILIZATION_LOG_DIVIDER 6
#define SERVOLIMIT 500
#define SCALE_FACTOR 4
#define CS2 ((1<<CS21)|(1<<CS20))
 
#else
 
#define NEUTRAL_PULSELENGTH 3750
#define STABILIZATION_LOG_DIVIDER 4
#define SERVOLIMIT 2000
#define SCALE_FACTOR 16
#define CS2 (1<<CS21)
#endif
 
#define MAX_SERVOS 8
#define FRAMELEN ((NEUTRAL_PULSELENGTH + SERVOLIMIT) * staticParams.servoCount + 128)
#define MIN_PULSELENGTH (NEUTRAL_PULSELENGTH - SERVOLIMIT)
#define MAX_PULSELENGTH (NEUTRAL_PULSELENGTH + SERVOLIMIT)
 
//volatile uint8_t servoActive = 0;
volatile uint8_t recalculateServoTimes = 0;
volatile uint16_t servoValues[MAX_SERVOS];
volatile uint16_t previousManualValues[2];
 
#define HEF4017R_ON     PORTC |=  (1<<PORTC6)
#define HEF4017R_OFF    PORTC &= ~(1<<PORTC6)
 
/*****************************************************
 *              Initialize Timer 2
 *****************************************************/
void timer2_init(void) {
    uint8_t sreg = SREG;
 
    // disable all interrupts before reconfiguration
    cli();
 
    // set PD7 as output of the PWM for pitch servo
    DDRD |= (1 << DDD7);
    PORTD &= ~(1 << PORTD7); // set PD7 to low
 
    DDRC |= (1 << DDC6); // set PC6 as output (Reset for HEF4017)
    HEF4017R_ON; // enable reset
 
    // Timer/Counter 2 Control Register A
    // Timer Mode is CTC (Bits: WGM22 = 0, WGM21 = 1, WGM20 = 0)
    // PD7: Output OCR2 match, (Bits: COM2A1 = 1, COM2A0 = 0)
    // PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0)
    TCCR2A &= ~((1 << COM2A0) | (1 << COM2B1) | (1 << COM2B0) | (1 << WGM20) | (1 << WGM22));
    TCCR2A |= (1 << COM2A1) | (1 << WGM21);
 
    // Timer/Counter 2 Control Register B
 
    // Set clock divider for timer 2 to 20MHz / 8 = 2.5 MHz
    // The timer increments from 0x00 to 0xFF with an update rate of 2.5 kHz or 0.4 us
    // hence the timer overflow interrupt frequency is 625 kHz / 256 = 9.765 kHz or 0.1024ms
 
    TCCR2B &= ~((1 << FOC2A) | (1 << FOC2B) | (1 << CS20) | (1 << CS21) | (1 << CS22));
    TCCR2B |= CS2;
 
    // Initialize the Timer/Counter 2 Register
    TCNT2 = 0;
 
    // Initialize the Output Compare Register A used for signal generation on port PD7.
    OCR2A = 255;
 
    // Timer/Counter 2 Interrupt Mask Register
    // Enable timer output compare match A Interrupt only
    TIMSK2 &= ~((1 << OCIE2B) | (1 << TOIE2));
    TIMSK2 |= (1 << OCIE2A);
 
    for (uint8_t axis=0; axis<2; axis++)
      previousManualValues[axis] = dynamicParams.servoManualControl[axis] * SCALE_FACTOR;
 
    SREG = sreg;
}
 
/*
void servo_On(void) {
    servoActive = 1;
}
void servo_Off(void) {
    servoActive = 0;
    HEF4017R_ON; // enable reset
}
*/
 
/*****************************************************
 * Control Servo Position
 *****************************************************/
int16_t calculateStabilizedServoAxis(uint8_t axis) {
  int32_t value = attitude[axis] >> STABILIZATION_LOG_DIVIDER; // between -500000 to 500000 extreme limits. Just about
  // With full blast on stabilization gain (255) we want to convert a delta of, say, 125000 to 2000.
  // That is a divisor of about 1<<14. Same conclusion as H&I.
  value *= staticParams.servoConfigurations[axis].stabilizationFactor;
  value = value >> 8;
  if (staticParams.servoConfigurations[axis].flags & SERVO_STABILIZATION_REVERSE)
    return -value;
  return value;
}
 
// With constant-speed limitation.
uint16_t calculateManualServoAxis(uint8_t axis, uint16_t manualValue) {
  int16_t diff = manualValue - previousManualValues[axis];
  uint8_t maxSpeed = staticParams.servoManualMaxSpeed;
  if (diff > maxSpeed) diff = maxSpeed;
  else if (diff < -maxSpeed) diff = -maxSpeed;
  manualValue = previousManualValues[axis] + diff;
  previousManualValues[axis] = manualValue;
  return manualValue;
}
 
// add stabilization and manual, apply soft position limits.
// All in a [0..255*SCALE_FACTOR] space (despite signed types used internally)
int16_t featuredServoValue(uint8_t axis) {
  int16_t value = calculateManualServoAxis(axis, dynamicParams.servoManualControl[axis] * SCALE_FACTOR);
  value += calculateStabilizedServoAxis(axis);
  int16_t limit = staticParams.servoConfigurations[axis].minValue * SCALE_FACTOR;
  if (value < limit) value = limit;
  limit = staticParams.servoConfigurations[axis].maxValue * SCALE_FACTOR;
  if (value > limit) value = limit;
  return value;
}
 
uint16_t servoValue(uint8_t axis) {
  int16_t value;
  if (axis<2) value = featuredServoValue(axis);
  else value = 128 * SCALE_FACTOR; // dummy. Replace by something useful for servos 3..8.
  // Shift out of the [0..255*SCALE_FACTOR] space
  value -= (128 * SCALE_FACTOR);
  if (value < -SERVOLIMIT) value = -SERVOLIMIT;
  else if (value > SERVOLIMIT) value = SERVOLIMIT;
  // Shift into the [NEUTRAL_PULSELENGTH-SERVOLIMIT..NEUTRAL_PULSELENGTH+SERVOLIMIT] space.
  return value + NEUTRAL_PULSELENGTH;
}
 
void calculateServoValues(void) {
  if (!recalculateServoTimes) return;
  for (uint8_t axis=0; axis<MAX_SERVOS; axis++) {
    servoValues[axis] = servoValue(axis);
  }
  recalculateServoTimes = 0;
}
 
uint8_t servoMap[] = {2,3,0,1,4,5,6,7};
 
ISR(TIMER2_COMPA_vect) {
  static uint16_t remainingPulseTime;
  static uint8_t servoIndex = 0;
  static uint16_t sumOfPulseTimes = 0;
 
  if (!remainingPulseTime) {
    // Pulse is over, and the next pulse has already just started. Calculate length of next pulse.
    if (servoIndex < staticParams.servoCount) {
      // There are more signals to output.
      sumOfPulseTimes += (remainingPulseTime = servoValues[servoMap[servoIndex]]);
      servoIndex++;
    } else {
      // There are no more signals. Reset the counter and make this pulse cover the missing frame time.
      remainingPulseTime = FRAMELEN - sumOfPulseTimes;
      sumOfPulseTimes = servoIndex = 0;
      recalculateServoTimes = 1;
      HEF4017R_ON;
    }
  }
 
  // Schedule the next OCR2A event. The counter is already reset at this time.
  if (remainingPulseTime > 256+128) {
    // Set output to reset to zero at next OCR match. It does not really matter when the output is set low again,
    // as long as it happens once per pulse. This will, because all pulses are > 255+128 long.
    OCR2A = 255;
    TCCR2A &= ~(1<<COM2A0);
    remainingPulseTime-=256;
  } else if (remainingPulseTime > 256) {
    // Remaining pulse lengths in the range [256..256+128] might cause trouble if handled the standard
    // way, which is in chunks of 256. The remainder would be very small, possibly causing an interrupt on interrupt
    // condition. Instead we now make a chunk of 128. The remaining chunk will then be in [128..255] which is OK.
    remainingPulseTime-=128;
    OCR2A=127;
  } else {
    // Set output to high at next OCR match. This is when the 4017 counter will advance by one. Also set reset low
    TCCR2A |= (1<<COM2A0);
    OCR2A = remainingPulseTime-1;
    remainingPulseTime=0;
    HEF4017R_OFF; // implement servo-disable here, by only removing the reset signal if ServoEnabled!=0.
  }
}
 

Subversion Repositories FlightCtrl

(root)/branches/dongfang_FC_rewrite/timer2.c @ 1720 - Rev 2117 → 2164

Rev 2117		Rev 2164
1	#include <avr/io.h>	1	#include <avr/io.h>
2	#include <avr/interrupt.h>	2	#include <avr/interrupt.h>
3	#include "eeprom.h"	3	#include "eeprom.h"
4	#include "rc.h"	4	#include "rc.h"
5	#include "attitude.h"	5	#include "attitude.h"
6		6
7	#define COARSERESOLUTION 1	7	#define COARSERESOLUTION 1
8		8
9	#ifdef COARSERESOLUTION	9	#ifdef COARSERESOLUTION
10	#define NEUTRAL_PULSELENGTH 938	10	#define NEUTRAL_PULSELENGTH 938
11	#define STABILIZATION_LOG_DIVIDER 6	11	#define STABILIZATION_LOG_DIVIDER 6
12	#define SERVOLIMIT 500	12	#define SERVOLIMIT 500
13	#define SCALE_FACTOR 4	13	#define SCALE_FACTOR 4
14	#define CS2 ((1<<CS21)\|(1<<CS20))	14	#define CS2 ((1<<CS21)\|(1<<CS20))
15		15
16	#else	16	#else
17		17
18	#define NEUTRAL_PULSELENGTH 3750	18	#define NEUTRAL_PULSELENGTH 3750
19	#define STABILIZATION_LOG_DIVIDER 4	19	#define STABILIZATION_LOG_DIVIDER 4
20	#define SERVOLIMIT 2000	20	#define SERVOLIMIT 2000
21	#define SCALE_FACTOR 16	21	#define SCALE_FACTOR 16
22	#define CS2 (1<<CS21)	22	#define CS2 (1<<CS21)
23	#endif	23	#endif
24		24
25	#define MAX_SERVOS 8	25	#define MAX_SERVOS 8
26	#define FRAMELEN ((NEUTRAL_PULSELENGTH + SERVOLIMIT) * staticParams.servoCount + 128)	26	#define FRAMELEN ((NEUTRAL_PULSELENGTH + SERVOLIMIT) * staticParams.servoCount + 128)
27	#define MIN_PULSELENGTH (NEUTRAL_PULSELENGTH - SERVOLIMIT)	27	#define MIN_PULSELENGTH (NEUTRAL_PULSELENGTH - SERVOLIMIT)
28	#define MAX_PULSELENGTH (NEUTRAL_PULSELENGTH + SERVOLIMIT)	28	#define MAX_PULSELENGTH (NEUTRAL_PULSELENGTH + SERVOLIMIT)
29		29
30	//volatile uint8_t servoActive = 0;	30	//volatile uint8_t servoActive = 0;
31	volatile uint8_t recalculateServoTimes = 0;	31	volatile uint8_t recalculateServoTimes = 0;
32	volatile uint16_t servoValues[MAX_SERVOS];	32	volatile uint16_t servoValues[MAX_SERVOS];
33	volatile uint16_t previousManualValues[2];	33	volatile uint16_t previousManualValues[2];
34		34
35	#define HEF4017R_ON PORTC \|= (1<<PORTC6)	35	#define HEF4017R_ON PORTC \|= (1<<PORTC6)
36	#define HEF4017R_OFF PORTC &= ~(1<<PORTC6)	36	#define HEF4017R_OFF PORTC &= ~(1<<PORTC6)
37		37
38	/*****************************************************	38	/*****************************************************
39	* Initialize Timer 2	39	* Initialize Timer 2
40	*****************************************************/	40	*****************************************************/
41	void timer2_init(void) {	41	void timer2_init(void) {
42	uint8_t sreg = SREG;	42	uint8_t sreg = SREG;
43		43
44	// disable all interrupts before reconfiguration	44	// disable all interrupts before reconfiguration
45	cli();	45	cli();
46		46
47	// set PD7 as output of the PWM for pitch servo	47	// set PD7 as output of the PWM for pitch servo
48	DDRD \|= (1 << DDD7);	48	DDRD \|= (1 << DDD7);
49	PORTD &= ~(1 << PORTD7); // set PD7 to low	49	PORTD &= ~(1 << PORTD7); // set PD7 to low
50		50
51	DDRC \|= (1 << DDC6); // set PC6 as output (Reset for HEF4017)	51	DDRC \|= (1 << DDC6); // set PC6 as output (Reset for HEF4017)
52	HEF4017R_ON; // enable reset	52	HEF4017R_ON; // enable reset
53		53
54	// Timer/Counter 2 Control Register A	54	// Timer/Counter 2 Control Register A
55	// Timer Mode is CTC (Bits: WGM22 = 0, WGM21 = 1, WGM20 = 0)	55	// Timer Mode is CTC (Bits: WGM22 = 0, WGM21 = 1, WGM20 = 0)
56	// PD7: Output OCR2 match, (Bits: COM2A1 = 1, COM2A0 = 0)	56	// PD7: Output OCR2 match, (Bits: COM2A1 = 1, COM2A0 = 0)
57	// PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0)	57	// PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0)
58	TCCR2A &= ~((1 << COM2A0) \| (1 << COM2B1) \| (1 << COM2B0) \| (1 << WGM20) \| (1 << WGM22));	58	TCCR2A &= ~((1 << COM2A0) \| (1 << COM2B1) \| (1 << COM2B0) \| (1 << WGM20) \| (1 << WGM22));
59	TCCR2A \|= (1 << COM2A1) \| (1 << WGM21);	59	TCCR2A \|= (1 << COM2A1) \| (1 << WGM21);
60		60
61	// Timer/Counter 2 Control Register B	61	// Timer/Counter 2 Control Register B
62		62
63	// Set clock divider for timer 2 to 20MHz / 8 = 2.5 MHz	63	// Set clock divider for timer 2 to 20MHz / 8 = 2.5 MHz
64	// The timer increments from 0x00 to 0xFF with an update rate of 2.5 kHz or 0.4 us	64	// The timer increments from 0x00 to 0xFF with an update rate of 2.5 kHz or 0.4 us
65	// hence the timer overflow interrupt frequency is 625 kHz / 256 = 9.765 kHz or 0.1024ms	65	// hence the timer overflow interrupt frequency is 625 kHz / 256 = 9.765 kHz or 0.1024ms
66		66
67	TCCR2B &= ~((1 << FOC2A) \| (1 << FOC2B) \| (1 << CS20) \| (1 << CS21) \| (1 << CS22));	67	TCCR2B &= ~((1 << FOC2A) \| (1 << FOC2B) \| (1 << CS20) \| (1 << CS21) \| (1 << CS22));
68	TCCR2B \|= CS2;	68	TCCR2B \|= CS2;
69		69
70	// Initialize the Timer/Counter 2 Register	70	// Initialize the Timer/Counter 2 Register
71	TCNT2 = 0;	71	TCNT2 = 0;
72		72
73	// Initialize the Output Compare Register A used for signal generation on port PD7.	73	// Initialize the Output Compare Register A used for signal generation on port PD7.
74	OCR2A = 255;	74	OCR2A = 255;
75		75
76	// Timer/Counter 2 Interrupt Mask Register	76	// Timer/Counter 2 Interrupt Mask Register
77	// Enable timer output compare match A Interrupt only	77	// Enable timer output compare match A Interrupt only
78	TIMSK2 &= ~((1 << OCIE2B) \| (1 << TOIE2));	78	TIMSK2 &= ~((1 << OCIE2B) \| (1 << TOIE2));
79	TIMSK2 \|= (1 << OCIE2A);	79	TIMSK2 \|= (1 << OCIE2A);
80		80
81	for (uint8_t axis=0; axis<2; axis++)	81	for (uint8_t axis=0; axis<2; axis++)
82	previousManualValues[axis] = dynamicParams.servoManualControl[axis] * SCALE_FACTOR;	82	previousManualValues[axis] = dynamicParams.servoManualControl[axis] * SCALE_FACTOR;
83		83
84	SREG = sreg;	84	SREG = sreg;
85	}	85	}
86		86
87	/*	87	/*
88	void servo_On(void) {	88	void servo_On(void) {
89	servoActive = 1;	89	servoActive = 1;
90	}	90	}
91	void servo_Off(void) {	91	void servo_Off(void) {
92	servoActive = 0;	92	servoActive = 0;
93	HEF4017R_ON; // enable reset	93	HEF4017R_ON; // enable reset
94	}	94	}
95	*/	95	*/
96		96
97	/*****************************************************	97	/*****************************************************
98	* Control Servo Position	98	* Control Servo Position
99	*****************************************************/	99	*****************************************************/
100	int16_t calculateStabilizedServoAxis(uint8_t axis) {	100	int16_t calculateStabilizedServoAxis(uint8_t axis) {
101	int32_t value = attitude[axis] >> STABILIZATION_LOG_DIVIDER; // between -500000 to 500000 extreme limits. Just about	101	int32_t value = attitude[axis] >> STABILIZATION_LOG_DIVIDER; // between -500000 to 500000 extreme limits. Just about
102	// With full blast on stabilization gain (255) we want to convert a delta of, say, 125000 to 2000.	102	// With full blast on stabilization gain (255) we want to convert a delta of, say, 125000 to 2000.
103	// That is a divisor of about 1<<14. Same conclusion as H&I.	103	// That is a divisor of about 1<<14. Same conclusion as H&I.
104	value *= staticParams.servoConfigurations[axis].stabilizationFactor;	104	value *= staticParams.servoConfigurations[axis].stabilizationFactor;
105	value = value >> 8;	105	value = value >> 8;
106	if (staticParams.servoConfigurations[axis].flags & SERVO_STABILIZATION_REVERSE)	106	if (staticParams.servoConfigurations[axis].flags & SERVO_STABILIZATION_REVERSE)
107	return -value;	107	return -value;
108	return value;	108	return value;
109	}	109	}
110		110
111	// With constant-speed limitation.	111	// With constant-speed limitation.
112	uint16_t calculateManualServoAxis(uint8_t axis, uint16_t manualValue) {	112	uint16_t calculateManualServoAxis(uint8_t axis, uint16_t manualValue) {
113	int16_t diff = manualValue - previousManualValues[axis];	113	int16_t diff = manualValue - previousManualValues[axis];
114	uint8_t maxSpeed = staticParams.servoManualMaxSpeed;	114	uint8_t maxSpeed = staticParams.servoManualMaxSpeed;
115	if (diff > maxSpeed) diff = maxSpeed;	115	if (diff > maxSpeed) diff = maxSpeed;
116	else if (diff < -maxSpeed) diff = -maxSpeed;	116	else if (diff < -maxSpeed) diff = -maxSpeed;
117	manualValue = previousManualValues[axis] + diff;	117	manualValue = previousManualValues[axis] + diff;
118	previousManualValues[axis] = manualValue;	118	previousManualValues[axis] = manualValue;
119	return manualValue;	119	return manualValue;
120	}	120	}
121		121
122	// add stabilization and manual, apply soft position limits.	122	// add stabilization and manual, apply soft position limits.
123	// All in a [0..255*SCALE_FACTOR] space (despite signed types used internally)	123	// All in a [0..255*SCALE_FACTOR] space (despite signed types used internally)
124	int16_t featuredServoValue(uint8_t axis) {	124	int16_t featuredServoValue(uint8_t axis) {
125	int16_t value = calculateManualServoAxis(axis, dynamicParams.servoManualControl[axis] * SCALE_FACTOR);	125	int16_t value = calculateManualServoAxis(axis, dynamicParams.servoManualControl[axis] * SCALE_FACTOR);
126	value += calculateStabilizedServoAxis(axis);	126	value += calculateStabilizedServoAxis(axis);
127	int16_t limit = staticParams.servoConfigurations[axis].minValue * SCALE_FACTOR;	127	int16_t limit = staticParams.servoConfigurations[axis].minValue * SCALE_FACTOR;
128	if (value < limit) value = limit;	128	if (value < limit) value = limit;
129	limit = staticParams.servoConfigurations[axis].maxValue * SCALE_FACTOR;	129	limit = staticParams.servoConfigurations[axis].maxValue * SCALE_FACTOR;
130	if (value > limit) value = limit;	130	if (value > limit) value = limit;
131	return value;	131	return value;
132	}	132	}
133		133
134	uint16_t servoValue(uint8_t axis) {	134	uint16_t servoValue(uint8_t axis) {
135	int16_t value;	135	int16_t value;
136	if (axis<2) value = featuredServoValue(axis);	136	if (axis<2) value = featuredServoValue(axis);
137	else value = 128 * SCALE_FACTOR; // dummy. Replace by something useful for servos 3..8.	137	else value = 128 * SCALE_FACTOR; // dummy. Replace by something useful for servos 3..8.
138	// Shift out of the [0..255*SCALE_FACTOR] space	138	// Shift out of the [0..255*SCALE_FACTOR] space
139	value -= (128 * SCALE_FACTOR);	139	value -= (128 * SCALE_FACTOR);
140	if (value < -SERVOLIMIT) value = -SERVOLIMIT;	140	if (value < -SERVOLIMIT) value = -SERVOLIMIT;
141	else if (value > SERVOLIMIT) value = SERVOLIMIT;	141	else if (value > SERVOLIMIT) value = SERVOLIMIT;
142	// Shift into the [NEUTRAL_PULSELENGTH-SERVOLIMIT..NEUTRAL_PULSELENGTH+SERVOLIMIT] space.	142	// Shift into the [NEUTRAL_PULSELENGTH-SERVOLIMIT..NEUTRAL_PULSELENGTH+SERVOLIMIT] space.
143	return value + NEUTRAL_PULSELENGTH;	143	return value + NEUTRAL_PULSELENGTH;
144	}	144	}
145		145
146	void calculateServoValues(void) {	146	void calculateServoValues(void) {
147	if (!recalculateServoTimes) return;	147	if (!recalculateServoTimes) return;
148	for (uint8_t axis=0; axis<MAX_SERVOS; axis++) {	148	for (uint8_t axis=0; axis<MAX_SERVOS; axis++) {
149	servoValues[axis] = servoValue(axis);	149	servoValues[axis] = servoValue(axis);
150	}	150	}
151	recalculateServoTimes = 0;	151	recalculateServoTimes = 0;
152	}	152	}
-		153
-		154	uint8_t servoMap[] = {2,3,0,1,4,5,6,7};
153		155
154	ISR(TIMER2_COMPA_vect) {	156	ISR(TIMER2_COMPA_vect) {
155	static uint16_t remainingPulseTime;	157	static uint16_t remainingPulseTime;
156	static uint8_t servoIndex = 0;	158	static uint8_t servoIndex = 0;
157	static uint16_t sumOfPulseTimes = 0;	159	static uint16_t sumOfPulseTimes = 0;
158		160
159	if (!remainingPulseTime) {	161	if (!remainingPulseTime) {
160	// Pulse is over, and the next pulse has already just started. Calculate length of next pulse.	162	// Pulse is over, and the next pulse has already just started. Calculate length of next pulse.
161	if (servoIndex < staticParams.servoCount) {	163	if (servoIndex < staticParams.servoCount) {
162	// There are more signals to output.	164	// There are more signals to output.
163	sumOfPulseTimes += (remainingPulseTime = servoValues[servoIndex]);	165	sumOfPulseTimes += (remainingPulseTime = servoValues[servoMap[servoIndex]]);
164	servoIndex++;	166	servoIndex++;
165	} else {	167	} else {
166	// There are no more signals. Reset the counter and make this pulse cover the missing frame time.	168	// There are no more signals. Reset the counter and make this pulse cover the missing frame time.
167	remainingPulseTime = FRAMELEN - sumOfPulseTimes;	169	remainingPulseTime = FRAMELEN - sumOfPulseTimes;
168	sumOfPulseTimes = servoIndex = 0;	170	sumOfPulseTimes = servoIndex = 0;
169	recalculateServoTimes = 1;	171	recalculateServoTimes = 1;
170	HEF4017R_ON;	172	HEF4017R_ON;
171	}	173	}
172	}	174	}
173		175
174	// Schedule the next OCR2A event. The counter is already reset at this time.	176	// Schedule the next OCR2A event. The counter is already reset at this time.
175	if (remainingPulseTime > 256+128) {	177	if (remainingPulseTime > 256+128) {
176	// Set output to reset to zero at next OCR match. It does not really matter when the output is set low again,	178	// Set output to reset to zero at next OCR match. It does not really matter when the output is set low again,
177	// as long as it happens once per pulse. This will, because all pulses are > 255+128 long.	179	// as long as it happens once per pulse. This will, because all pulses are > 255+128 long.
178	OCR2A = 255;	180	OCR2A = 255;
179	TCCR2A &= ~(1<<COM2A0);	181	TCCR2A &= ~(1<<COM2A0);
180	remainingPulseTime-=256;	182	remainingPulseTime-=256;
181	} else if (remainingPulseTime > 256) {	183	} else if (remainingPulseTime > 256) {
182	// Remaining pulse lengths in the range [256..256+128] might cause trouble if handled the standard	184	// Remaining pulse lengths in the range [256..256+128] might cause trouble if handled the standard
183	// way, which is in chunks of 256. The remainder would be very small, possibly causing an interrupt on interrupt	185	// way, which is in chunks of 256. The remainder would be very small, possibly causing an interrupt on interrupt
184	// condition. Instead we now make a chunk of 128. The remaining chunk will then be in [128..255] which is OK.	186	// condition. Instead we now make a chunk of 128. The remaining chunk will then be in [128..255] which is OK.
185	remainingPulseTime-=128;	187	remainingPulseTime-=128;
186	OCR2A=127;	188	OCR2A=127;
187	} else {	189	} else {
188	// Set output to high at next OCR match. This is when the 4017 counter will advance by one. Also set reset low	190	// Set output to high at next OCR match. This is when the 4017 counter will advance by one. Also set reset low
189	TCCR2A \|= (1<<COM2A0);	191	TCCR2A \|= (1<<COM2A0);
190	OCR2A = remainingPulseTime-1;	192	OCR2A = remainingPulseTime-1;
191	remainingPulseTime=0;	193	remainingPulseTime=0;
192	HEF4017R_OFF; // implement servo-disable here, by only removing the reset signal if ServoEnabled!=0.	194	HEF4017R_OFF; // implement servo-disable here, by only removing the reset signal if ServoEnabled!=0.
193	}	195	}
194	}	196	}
195		197