Joseph Bradshaw / ServoOut

Library for generating servo pulses from mbed output pins

Dependents:   mbed_ES20X_Tester MadPulseCntrl ES413Integration Emaxx_Navigation ... more

Fork of SERVOGEN by Joseph Bradshaw

ServoOut Library

Assign the ServoOut object (output pin) a value in microseconds to change the servo pulse. Note that the default range is between 900 and 2100 microseconds.

Library for generating servo pulses using the Ticker class

/media/uploads/jebradshaw/mbedwsesbc_servos.jpg

/media/uploads/jebradshaw/mbed_servo_pulses.jpg

include the mbed library with this snippet

// ServoOut Class test program
// J. Bradshaw 20140925
#include "mbed.h"
#include "ServoOut.h" 
 
ServoOut servo1(p21);
ServoOut servo2(p24);
DigitalOut led1(LED1);
 
int main() {
    servo1.pulse_us = 0;        
    // spin in a main loop. flipper will interrupt it to call flip
    while(1) {
        for(float cycle=0.0;cycle<2.0*3.14159;cycle+=.003){
            //small amplitude sine wave on servo1
            servo1 = 300 * sin(cycle) + 1500;            
            //ramp up the second servo2 channel relative to cycle
            servo2 = 1000 + cycle*159; // .001/(2*PI)
            
            wait(.001); //short delay
        }
        led1 = !led1;   //toggle led1 to indicate activity
    }//while(1)
}//main

Diff: ServoOut.cpp

Revision:
5:74d2f30b4dd6
Child:
6:6a59017c4f62
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ServoOut.cpp	Fri Apr 10 17:07:00 2015 +0000
@@ -0,0 +1,85 @@
+// Uses attach_us to generate servo pulse on single output pin
+// J. Bradshaw 20140925
+/* Copyright (c) 2014, jbradshaw (http://mbed.org)
+ *
+ * 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 "mbed.h"
+#include "ServoOut.h"
+
+ServoOut::ServoOut(PinName pin) : _pin(pin) {
+    _pin = 0;           // Initialize output pin as off
+    _sCycle = 0;        // initialize servo cycle as 0
+    pulseMin=900;       // default minimum (except 0) servo pulse width
+    pulseMax=2100;      // maximum servo pulse width
+    pulse_us=0;         // Initialize servo pulse width as 0
+    ticker = new Ticker();  // instantiate new Ticker object
+    ticker->attach_us(this,&ServoOut::tickFunct,20000); //begin tickFunction in 20ms
+}
+
+void ServoOut::tickFunct(void){
+    
+    if(pulse_us == 0){  //first check to see if the pulse width is 0 (OFF, servo not powered)
+        _pin=0;         // disable servo pulse output
+        ticker->attach_us(this,&ServoOut::tickFunct,20000); // recall this function in 20ms
+        return;
+    }
+    
+    else{        
+        if(pulse_us < pulseMin)     //keep within bounds
+            pulse_us = pulseMin;
+        if(pulse_us > pulseMax)
+            pulse_us = pulseMax;
+        
+        if(_sCycle){   //mode == 1
+            //pulse was high, now drop low for remaining time
+            ticker->attach_us(this,&ServoOut::tickFunct,20000-pulse_us);; // recall this function in 20ms - servo pulse width (servo pulse low)
+            _pin=0;    
+            _sCycle=0;
+        }
+        else{   //mode == 0
+            ticker->attach_us(this,&ServoOut::tickFunct,pulse_us);; // recall this function in 20ms - pulse width (servo pulse high)
+            _pin=1;        
+            _sCycle=1;
+        }
+    } //pulse != 0 (OFF)
+}
+
+void ServoOut::write(int pulse){
+    pulse_us = pulse;    
+}
+
+int ServoOut::read(){
+    return pulse_us;    
+}
+
+ServoOut& ServoOut::operator= (int pulse_us) { 
+    write(pulse_us);
+    return *this;
+}
+ 
+ServoOut& ServoOut::operator= (ServoOut& rhs) {
+    write(rhs.read());
+    return *this;
+}
+ 
+ServoOut::operator int() {
+    return read();
+}
\ No newline at end of file