aboutsummaryrefslogtreecommitdiffstats
path: root/libraries/Servo/Servo.cpp
blob: ae87b63d8faffe3004e7c6419d4459ad1065ceea (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
/******************************************************************************
 * The MIT License
 *
 * Copyright (c) 2010, LeafLabs, LLC.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *****************************************************************************/

#include "Servo.h"

#include "boards.h"
#include "io.h"
#include "pwm.h"
#include "wirish_math.h"

// Configure prescaler and overflow for a 20msec period (could just
// use HardwareTimer::setPeriod(), but this lets conversions below
// happen more statically, in combination with an inlined map() -- a
// premature optimization? TODO profile speed/size tradeoff)
#define CYC_20MSEC     (20000 * CYCLES_PER_MICROSECOND)
#define SERVO_PRE ((uint16)((CYC_20MSEC >> 16) + 1))
#define SERVO_OVF ((uint16)((CYC_20MSEC / SERVO_PRE) - 1))
#define SERVO_TAU_USEC \
    ((uint32)(((double)SERVO_OVF) * SERVO_PRE / CYCLES_PER_MICROSECOND + 0.5))

#define US_TO_COMPARE(us) ((uint16)map(us, 0, SERVO_TAU_USEC, 0, SERVO_OVF))
#define COMPARE_TO_US(c)  ((uint32)map(c, 0, SERVO_OVF, 0, SERVO_TAU_USEC))

#define ANGLE_TO_US(a)  ((uint16)(map(a, 0, 180, this->min, this->max)))
#define US_TO_ANGLE(us) ((uint8)(map(us, this->min, this->max, 0, 180)))

Servo::Servo() {
    this->pin = NOT_ATTACHED;
    this->timer = 0;
    this->channel = TIMER_INVALID;
    this->min = SERVO_DEFAULT_MIN_PW;
    this->max = SERVO_DEFAULT_MAX_PW;
}

bool Servo::attach(uint8_t pin) {
    return this->attach(pin, SERVO_DEFAULT_MIN_PW, SERVO_DEFAULT_MAX_PW);
}

bool Servo::attach(uint8_t pin, uint16_t min, uint16_t max) {
    timer_dev_num timer_num = PIN_MAP[pin].timer_num;
    uint32_t channel = PIN_MAP[pin].timer_chan;
    if (timer_num == TIMER_INVALID) {
        // don't reset any members or ASSERT(0), to keep driving any
        // previously attach()ed servo.
        return false;
    }
    this->pin = pin;
    this->timer = getTimer(timer_num);
    this->channel = channel;
    this->min = min;
    this->max = max;

    pinMode(pin, PWM);

    this->timer->pause();
    this->timer->setPrescaleFactor(SERVO_PRE);
    this->timer->setOverflow(SERVO_OVF);
    this->timer->generateUpdate();
    this->timer->resume();
    return true;
}

bool Servo::detach() {
    if (this->pin == NOT_ATTACHED) return false;

    this->timer->setChannelMode(this->channel, TIMER_DISABLED);

    this->pin = NOT_ATTACHED;
    this->timer = 0;
    this->channel = TIMER_INVALID;
    this->min = SERVO_DEFAULT_MIN_PW;
    this->max = SERVO_DEFAULT_MAX_PW;

    return true;
}

void Servo::write(unsigned int value) {
    if (value < SERVO_MAX_WRITE_ANGLE) {
        this->writeMicroseconds(ANGLE_TO_US(value));
    } else {
        this->writeMicroseconds(value);
    }
}

void Servo::writeMicroseconds(uint16_t pulseWidth) {
    if (this->pin == NOT_ATTACHED) {
        ASSERT(0);
        return;
    }

    pulseWidth = constrain(pulseWidth, this->min, this->max);
    pwmWrite(this->pin, US_TO_COMPARE(pulseWidth));
}

int Servo::read() const {
    if (this->pin == NOT_ATTACHED) {
        ASSERT(0);
        return 0;
    }

    unsigned int pw = this->readMicroseconds();
    int a = US_TO_ANGLE(pw);
    // map() round-trips in a weird way we correct for here
    return a == 0 || a == 180 ? a : a + 1;
}

uint16_t Servo::readMicroseconds() const {
    if (this->pin == NOT_ATTACHED) {
        ASSERT(0);
        return 0;
    }

    unsigned int compare = this->timer->getCompare(this->channel);
    uint16_t c = COMPARE_TO_US(compare);
    // map() round-trips in a weird way we correct for here
    return c == 0 || c == 180 ? c : c + 1;
}