Diff: main.cpp

Revision:

0:49ae6bc4220c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Sep 09 01:33:16 2010 +0000
@@ -0,0 +1,83 @@
+#include "mbed.h"
+
+//playing with servos...
+// Controlling the servo position with a potenciometer.
+
+// the servo must be powered from an external device, 
+// since mbed, will cut it out when the  current goes up 400mA.
+// just remember to ground the external batteries, chargers, ...
+// to the GND pin. 
+
+//  trick!:  when control signal goes to 0V. the servo goes freely and dont
+// hold any stall torque!-> that could be useful sometimes, ... to load some
+// mechanism, or as a safety measurement.
+        
+
+PwmOut myservo(p21); //PWM servo control signal goes here
+
+//   ______       Position 0 degrees
+//  |      |_______________________________________________
+//  <-1ms->  0.05%duty cycle
+//
+//   __________________     Position 180 degrees
+//  |                  |___________________________________
+//  <-------2.1ms----->  0.1%aprox. duty cycle
+//
+//  <----------------------------20ms---------------------->
+
+
+
+AnalogIn input(p20); //analog input is wired to a potenciometer, range 0->3.3V
+                     //and the value is represented as a float, range 0->1.
+
+//as the input range is from 0 to 1, and the PWM control, ranges is 
+//from 0.05% to 0.1% is pretty easy make the control! 
+//with the PWM .write() method,sets the duty cycle specified as a fload in range 0->1
+//so, for the control only divide by 10 the input, is needed.
+
+
+//some ultra-light blue leds, for adding a cool effect!
+DigitalOut led1(LED1);
+DigitalOut led2(LED2);
+DigitalOut led3(LED3);
+DigitalOut led4(LED4);
+
+int main() {
+     float ain;    //ain-> Analog INput<- connected to a potenciometer for controlling the servo
+     float period=20;
+  
+     myservo.period_ms(period);
+     
+    while (1) {
+    
+      ain=input.read();//the analog reading, is expressed as a float
+                       // with values from 0 to 1. 1 stands for max. voltage= 3.3V
+        
+        if (ain<0.02){                   //if voltage is sooo low...
+        led1=0; led2=0; led3=0; led4=0;  //no leds!
+        ain=0;                           //no control signal-> no torque, so you can 
+                                         //use it as safety measurement, or to manualy move the servo position.
+        }
+        else if ( ain>0.02 && ain<0.33){  // When the LED1 turns on, is because you have just hitted the 0 degrees position.
+        led1=1; led2=0; led3=0; led4=0;   // LED1 will be on from 0 to 60 degrees. ... aprox. :)
+        }
+        else if ( ain>0.33 && ain<0.66){   // LED2 switch on, when you pass the 60 degrees.
+        led1=1; led2=1; led3=0; led4=0;
+        }
+        else if ( ain>0.66 && ain<0.95){  // LED3 switch on, when you pass 120 degrees
+        led1=1; led2=1; led3=1; led4=0;
+        } 
+        else {                           // LED4. you are at 180 degrees.
+        led1=1; led2=2; led3=1; led4=1;
+        }
+        
+        
+        myservo.write(ain/10);
+        
+        } // end while(1)
+    
+}//end main()
+
+
+
+