1 files changed, 150 insertions, 0 deletions
diff --git a/libraries/Servo/Servo.cpp b/libraries/Servo/Servo.cpp
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+++ b/libraries/Servo/Servo.cpp
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+/******************************************************************************
+ * 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 <wirish/boards.h>
+#include <wirish/io.h>
+#include <wirish/pwm.h>
+#include <wirish/wirish_math.h>
+
+// 20 millisecond period config.  For a 1-based prescaler,
+//
+//    (prescaler * overflow / CYC_MSEC) msec = 1 timer cycle = 20 msec
+// => prescaler * overflow = 20 * CYC_MSEC
+//
+// This picks the smallest prescaler that allows an overflow < 2^16.
+#define MAX_OVERFLOW    ((1 << 16) - 1)
+#define CYC_MSEC        (1000 * CYCLES_PER_MICROSECOND)
+#define TAU_MSEC        20
+#define TAU_USEC        (TAU_MSEC * 1000)
+#define TAU_CYC         (TAU_MSEC * CYC_MSEC)
+#define SERVO_PRESCALER (TAU_CYC / MAX_OVERFLOW + 1)
+#define SERVO_OVERFLOW  ((uint16)round((double)TAU_CYC / SERVO_PRESCALER))
+
+// Unit conversions
+#define US_TO_COMPARE(us) ((uint16)map((us), 0, TAU_USEC, 0, SERVO_OVERFLOW))
+#define COMPARE_TO_US(c)  ((uint32)map((c), 0, SERVO_OVERFLOW, 0, TAU_USEC))
+#define ANGLE_TO_US(a)    ((uint16)(map((a), this->minAngle, this->maxAngle, \
+                                        this->minPW, this->maxPW)))
+#define US_TO_ANGLE(us)   ((int16)(map((us), this->minPW, this->maxPW,  \
+                                       this->minAngle, this->maxAngle)))
+
+Servo::Servo() {
+    this->resetFields();
+}
+
+bool Servo::attach(uint8 pin,
+                   uint16 minPW,
+                   uint16 maxPW,
+                   int16 minAngle,
+                   int16 maxAngle) {
+    timer_dev *tdev = PIN_MAP[pin].timer_device;
+
+    if (tdev == NULL) {
+        // don't reset any fields or ASSERT(0), to keep driving any
+        // previously attach()ed servo.
+        return false;
+    }
+
+    if (this->attached()) {
+        this->detach();
+    }
+
+    this->pin = pin;
+    this->minPW = minPW;
+    this->maxPW = maxPW;
+    this->minAngle = minAngle;
+    this->maxAngle = maxAngle;
+
+    pinMode(pin, PWM);
+
+    timer_pause(tdev);
+    timer_set_prescaler(tdev, SERVO_PRESCALER - 1); // prescaler is 1-based
+    timer_set_reload(tdev, SERVO_OVERFLOW);
+    timer_generate_update(tdev);
+    timer_resume(tdev);
+
+    return true;
+}
+
+bool Servo::detach() {
+    if (!this->attached()) {
+        return false;
+    }
+
+    timer_dev *tdev = PIN_MAP[this->pin].timer_device;
+    uint8 tchan = PIN_MAP[this->pin].timer_channel;
+    timer_set_mode(tdev, tchan, TIMER_DISABLED);
+
+    this->resetFields();
+
+    return true;
+}
+
+void Servo::write(int degrees) {
+    degrees = constrain(degrees, this->minAngle, this->maxAngle);
+    this->writeMicroseconds(ANGLE_TO_US(degrees));
+}
+
+int Servo::read() const {
+    int a = US_TO_ANGLE(this->readMicroseconds());
+    // map() round-trips in a weird way we mostly correct for here;
+    // the round-trip is still sometimes off-by-one for write(1) and
+    // write(179).
+    return a == this->minAngle || a == this->maxAngle ? a : a + 1;
+}
+
+void Servo::writeMicroseconds(uint16 pulseWidth) {
+    if (!this->attached()) {
+        ASSERT(0);
+        return;
+    }
+
+    pulseWidth = constrain(pulseWidth, this->minPW, this->maxPW);
+    pwmWrite(this->pin, US_TO_COMPARE(pulseWidth));
+}
+
+uint16 Servo::readMicroseconds() const {
+    if (!this->attached()) {
+        ASSERT(0);
+        return 0;
+    }
+
+    stm32_pin_info pin_info = PIN_MAP[this->pin];
+    uint16 compare = timer_get_compare(pin_info.timer_device,
+                                       pin_info.timer_channel);
+
+    return COMPARE_TO_US(compare);
+}
+
+void Servo::resetFields(void) {
+    this->pin = NOT_ATTACHED;
+    this->minAngle = SERVO_DEFAULT_MIN_ANGLE;
+    this->maxAngle = SERVO_DEFAULT_MAX_ANGLE;
+    this->minPW = SERVO_DEFAULT_MIN_PW;
+    this->maxPW = SERVO_DEFAULT_MAX_PW;
+}