Servo library tested and debugged.

Some additional HardwareTimer methods introduced to make this
convenient; ancillary libmaple/timers.h changes resulted.

1 files changed, 138 insertions, 0 deletions

diff --git a/libraries/Servo/Servo.cpp b/libraries/Servo/Servo.cpp
new file mode 100644
index 0000000..4f60fbe
--- /dev/null
+++ b/libraries/Servo/Servo.cpp
@@ -0,0 +1,138 @@
+/******************************************************************************
+ * 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 "boards.h"
+#include "io.h"
+#include "pwm.h"
+#include "wirish_math.h"
+
+#include "Servo.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;
+}