root / branches / encoders / code / behaviors / spline / server / encoders.c @ 1238
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#include "encoders.h" |
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char encoder_buf_index;
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unsigned int left_data, right_data; |
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unsigned int left_data_array[BUFFER_SIZE]; |
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unsigned int right_data_array[BUFFER_SIZE]; |
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int left_data_idx;
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int right_data_idx;
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int left_dx;
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int right_dx;
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long int timecount; |
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volatile short int data_ready; |
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void encoder_recv(unsigned int, unsigned int); |
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//Helper Function Prototypes
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inline void left_data_array_put(unsigned short int value); |
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inline unsigned int left_data_array_top(void); |
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inline unsigned int left_data_array_prev(void); |
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inline unsigned int left_data_array_bottom(void); |
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inline void right_data_array_put(unsigned short int value); |
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inline unsigned int right_data_array_top(void); |
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inline unsigned int right_data_array_prev(void); |
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inline unsigned int right_data_array_bottom(void); |
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/**
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* @brief Returns the specified encoders value
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*
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* @param encoder this is the encoder that you want to read. Valid arguments
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* are LEFT and RIGHT
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*
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* @return the value of the specified encoder
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**/
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int encoder_read(char encoder){ |
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if(encoder==LEFT) return left_data; |
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else if(encoder==RIGHT) return right_data; |
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else return -1; |
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} |
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/**
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* @brief Outputs encoder direction as FORWARD OR BACK
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* A STUB! DO NOT use.
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*
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* @param encoder The encoder you want the direction of.
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* Valid arguments are right and left.
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*
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* @return FORWARD or BACK (the constants)
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*/
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char encoder_direction(char encoder){ |
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return 0; |
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} |
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/**
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* Gets the total distance covered by the specified encoder (in encoder clicks)
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*
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* @param encoder the encoder that you want to read, use LEFT or RIGHT
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*
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* @return The distance covered by the specified encoder.
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**/
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int encoder_get_dx(char encoder) { |
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if(encoder==LEFT) return left_dx; |
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else if(encoder==RIGHT) return right_dx; |
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else return -1; |
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} |
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/**
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* Resets the distance accumulator for the specified
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* encoder.
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*
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* @param encoder the encoder that you want to reset distance for
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**/
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void encoder_rst_dx(char encoder) { |
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if(encoder==LEFT) left_dx = 0; |
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else if(encoder==RIGHT) right_dx = 0; |
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} |
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/**
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* @brief Returns the number of encoder reads that have occurred.
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*
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* @return The time count.
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*/
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int encoder_get_tc(void) { |
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return timecount;
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} |
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/**
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* @brief Resets the encoder read counter.
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*/
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void encoder_rst_tc(void) { |
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timecount = 0;
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} |
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/**
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* @brief Returns the approximated instantaneous velocity of the robot
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* in terms of encoder clicks.
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*
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* @param encoder RIGHT or LEFT - the wheel you want the velocity for.
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*
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* @return The instantaneous velocity for the given wheel.
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*/
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int encoder_get_v(char encoder){ |
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if (encoder == LEFT)
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return left_data_array_bottom() - left_data_array_top();
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if (encoder == RIGHT)
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return right_data_array_top() - right_data_array_bottom();
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return -1; /* TODO: velocity could be -1, use another value for error */ |
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} |
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/**
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* @brief Waits until n encoder reads have occurred.
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* Counter is reset on functions exit.
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*
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* @param n
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*/
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void encoder_wait(int n){ |
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while(data_ready<n);
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data_ready=0;
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} |
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//Full reads occur every 40 microseconds. This function should be called
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//every 8 microseconds.
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void encoder_recv(unsigned int left_data_buf, unsigned int right_data_buf){ |
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short int dx; |
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left_data = left_data_buf; |
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right_data = right_data_buf; |
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/*Above 1023 is invalid data*/
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if(!(left_data > 1023)) { |
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left_data_array_put(left_data); |
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//Adjust left accumulator
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dx = - left_data + left_data_array_prev(); |
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if(left_data_array_prev()==0) dx=0; |
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if(dx > 512) left_dx += dx - 1023; //Underflow |
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else if(dx < -512) left_dx += dx + 1023; //Overflow |
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else left_dx += dx;
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} |
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/*Above 1023 is invalid data*/
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if(!(right_data > 1023)) { |
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right_data_array_put(right_data); |
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//Adjust right accumulator
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dx = right_data - right_data_array_prev(); |
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if(right_data_array_prev()==0) dx=0; |
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if(dx > 512) right_dx += dx - 1023; //underflow |
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else if(dx < -512) right_dx += dx + 1023; //overflow |
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else right_dx += dx;
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} |
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//Increment timecount accumulator
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timecount++; |
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} |
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//Helper Functions
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inline void left_data_array_put(unsigned short int value) { |
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if(left_data_idx == BUFFER_SIZE-1) |
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left_data_idx = 0;
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else
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left_data_idx++; |
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left_data_array[left_data_idx] = value; |
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} |
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inline unsigned int left_data_array_top(void) { |
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return left_data_array[left_data_idx];
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} |
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inline unsigned int left_data_array_prev(void) { |
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if(left_data_idx == 0) |
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return left_data_array[BUFFER_SIZE-1]; |
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else
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return left_data_array[left_data_idx - 1]; |
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} |
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inline unsigned int left_data_array_bottom(void) { |
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if(left_data_idx == BUFFER_SIZE-1) |
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return left_data_array[0]; |
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else
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return left_data_array[left_data_idx + 1]; |
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} |
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inline void right_data_array_put(unsigned short int value) { |
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if(right_data_idx == BUFFER_SIZE-1) |
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right_data_idx = 0;
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else
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right_data_idx++; |
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right_data_array[right_data_idx] = value; |
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} |
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inline unsigned int right_data_array_top(void) { |
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return right_data_array[right_data_idx];
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} |
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inline unsigned int right_data_array_prev(void) { |
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if(right_data_idx == 0) |
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return right_data_array[BUFFER_SIZE-1]; |
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else
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return right_data_array[right_data_idx - 1]; |
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} |
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inline unsigned int right_data_array_bottom(void) { |
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if(right_data_idx == BUFFER_SIZE-1) |
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return right_data_array[0]; |
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else
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return right_data_array[right_data_idx + 1]; |
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} |
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