Diff: main.cpp

Revision:

0:a3da4faf20a8

Child:

1:fac3a5bf41dd

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Feb 08 18:54:20 2014 +0000
@@ -0,0 +1,99 @@
+/**
+   @file
+   @brief MUTT controller, version 1.
+          MUTT will keep going until an obstacle is detected at which
+            point it'll stop and politely wait (indefinately) for the
+            obstacle to move.
+            
+          See http://mbed.org/users/johnb/notebook/mutt-mbed-enabled-robot-vehicle/
+   
+   @author John Bailey 
+
+   @copyright Copyright 2014 John Bailey
+
+   @section LICENSE
+   
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+*/
+
+#include "mbed.h"
+
+/* Remove the comment to get some output on the serial line, however this
+   may result in problems if the serial line's not connected (i.e. MUTT's
+   not USB connected and is free roaming */
+//#define SERIAL_OUTPUT
+
+#if defined SERIAL_OUTPUT
+Serial pc(USBTX, USBRX); 
+#define OUTPUT_PERIOD 1000
+#endif
+
+/* Connections to the Motor Shield.  These will need to be changed for boards 
+   other than the KL46Z and it also assumes the presence of the cross-wiring
+   on PWM B (see "Issues" at http://mbed.org/users/johnb/notebook/mutt-mbed-enabled-robot-vehicle/ )
+*/
+AnalogIn irFeedback(PTC2  /* A4 */);
+PwmOut pwm_b( PTA5 );
+PwmOut pwm_a( PTA12 );
+DigitalOut dir_a(PTD7);
+DigitalOut dir_b(PTD5);
+
+/** Determine if the IR sensor is detecting an obstacle */
+bool irSensesObstacle( void )
+{
+    /* IR sensor is TTL, so threshold is arbitary */
+    static const float ir_thresh = 0.5;
+    
+    /* If analogue feedback is less than the threshold then there's an obstacle */
+    return( irFeedback < ir_thresh );
+}
+ 
+int main( void )
+{
+#if defined SERIAL_OUTPUT
+    uint16_t ticker = 0;
+    uint16_t next_output = 0;
+#endif        
+
+    /* Set directions on the motors.  What you need here will depend on how 
+       you've wired the motors to the motor shield.  If you find that one or 
+       both wheels are turning backwards then you can either change the wiring 
+       or change these settings */    
+    dir_a = 0;
+    dir_b = 1;
+    
+    /* Forever is a long time ... */
+    while( 1 )
+    { 
+        /* Determine if there's an obstacle */
+        bool obstacle = irSensesObstacle();
+#if defined SERIAL_OUTPUT
+        if( next_output == OUTPUT_PERIOD ) 
+        {
+            pc.printf( "MUTT: %04u %u\r\n",ticker++,obstacle);
+            next_output = 0;
+        }
+        next_output++;
+#endif        
+        
+        /* Set the PWM to both motors to 1 (i.e. 100%) in the case that there's
+           no obstacle, set it to 0 (i.e. 0%) in the case that ab obstacle is
+           detected */ 
+        pwm_a.write( !obstacle );
+        pwm_b.write( !obstacle );
+
+        /* Wait 1 millisecond before goind round the loop again */
+        wait_ms( 1 );
+    }
+}
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