root / demos / hunter_prey / lib / src / libdragonfly / encoders.c @ 1828
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#include "encoders.h" |
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#include "spi.h" |
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#include "ring_buffer.h" |
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#include <avr/io.h> |
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unsigned int left_data_buf; |
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unsigned int right_data_buf; |
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char encoder_buf_index;
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unsigned int left_data; |
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unsigned int 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(char data); |
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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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//encoder_get_v helper function prototypes
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int left_data_at(int index); |
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int right_data_at(int index); |
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int get_dx(char encoder, int index); |
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void encoder_recv_complete(void){ |
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encoder_buf_index = 0;
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data_ready++; |
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spi_transfer(5);
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} |
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/**
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* @brief Initializes encoder variables and the hardware interface.
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*/
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void encoders_init(void){ |
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int i;
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data_ready=0;
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spi_init(encoder_recv, encoder_recv_complete); |
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encoder_buf_index = 0;
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left_data_buf = 0;
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right_data_buf= 0;
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left_data = -1;
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right_data = -1;
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//RING_BUFFER_INIT(enc_buffer,BUFFER_SIZE);
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left_data_idx = 0;
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right_data_idx = 0;
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for(i = 0; i < BUFFER_SIZE; i++) { |
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left_data_array[i] = 0;
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} |
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for(i = 0; i < BUFFER_SIZE; i++) { |
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right_data_array[i] = 0;
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} |
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spi_transfer(5);
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} |
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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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* -1 usually means low battery.
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* values above ENCODER_MAX usually means phyiscal problems with
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* the 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 Get total distance travelled by the specified encoder (in encoder ticks)
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*
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* @param encoder the encoder that you want to read, either 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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* @note Simply calls encoder_get_dx.
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**/
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int encoder_get_x(char encoder) { |
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return encoder_get_dx(encoder);
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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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* @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 or twice the ERR_VEL
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* if an error occurs (1024 * 2 = 2048)
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*
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* @bug This uses hard coded values and results are inconsistent.
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* Use at your own risk.
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*/
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int encoder_get_v(char encoder){ |
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int vel1, vel2;
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vel1 = get_dx(encoder, 0);
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vel2 = get_dx(encoder, 1);
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if (vel1 == ERR_VEL && vel2 == ERR_VEL)
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return ERR_VEL << 1; |
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else if (vel2 == ERR_VEL) |
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return vel1 << 1; |
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else if (vel1 == ERR_VEL) |
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return vel2 << 1; |
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else
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return vel1 + vel2;
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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 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(char data){ |
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short int dx; |
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//Parse the encoder data, comes in over 5 bytes 16 bits per encoder,
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// second is offset by 1 bit.
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switch(encoder_buf_index){
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case 0: |
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right_data_buf |= ((short)data)<<8 & 0xff00; |
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break;
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case 1: |
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right_data_buf |= ((short)data) & 0xff; |
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break;
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case 2: |
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left_data_buf |= (((short)data) << 9) & (0x7F << 9); |
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break;
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case 3: |
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left_data_buf |= (((short)data) << 1) & (0xFF<<1); |
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break;
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case 4: left_data_buf |= (((short)data)>>7) & 0x1; |
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} |
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encoder_buf_index = (encoder_buf_index + 1) % 5; |
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if(encoder_buf_index==0) { |
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/*Error handling for the left encoder*/
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if(!(left_data_buf & OCF))
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left_data = ENCODER_DATA_NOT_READY; |
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if(left_data_buf & (COF | LIN))
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left_data = ENCODER_MISALIGNED; |
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else if((left_data_buf & MagINCn) && (left_data_buf & MagDECn)) |
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left_data = ENCODER_MAGNET_FAILURE; |
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else left_data = (left_data_buf>>5) & 1023; |
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/*Error handling for the right encoder*/
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if(!(right_data_buf & OCF))
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right_data = ENCODER_DATA_NOT_READY; |
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if(right_data_buf & (COF | LIN))
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right_data = ENCODER_MISALIGNED; |
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else if ((right_data_buf & MagINCn) && (right_data_buf & MagDECn)) |
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right_data = ENCODER_MAGNET_FAILURE; |
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else right_data = (right_data_buf>>5) & 1023; |
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left_data_buf = 0;
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right_data_buf = 0;
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/*Note: Above 1023 is invalid data*/
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if(!(left_data > 1023)) { |
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//Reverse the left wheel since encoders are necessarily mounted backwards.
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left_data = 1023 - left_data;
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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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} |
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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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/* Helper functions for encoder_get_v */
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int left_data_at(int index) { |
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int tmp_idx = left_data_idx - index;
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if (tmp_idx < 0) |
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tmp_idx += BUFFER_SIZE; |
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return left_data_array[tmp_idx];
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} |
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int right_data_at(int index) { |
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int tmp_idx = right_data_idx - index;
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if (tmp_idx < 0) |
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tmp_idx += BUFFER_SIZE; |
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return right_data_array[tmp_idx];
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} |
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int get_dx(char encoder, int index) { |
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int dx, ctr;
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ctr = 0;
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dx = 1024;
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do {
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if (encoder == LEFT)
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dx = left_data_at(index+ctr) - left_data_at(index+ctr+38);
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else
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dx = right_data_at(index+ctr) - right_data_at(index+ctr+38);
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ctr++; |
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} while ((dx > 30 || dx < -30) && ctr < 3); |
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if (dx > 30 || dx < -30) |
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return ERR_VEL;
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return dx;
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} |