MM2WayRanging.h

00001 // by Matthias Grob & Manuel Stalder - ETH Zürich - 2015
00002 
00003 #ifndef MM2WAYRANGING_H
00004 #define MM2WAYRANGING_H
00005 
00006 #include "mbed.h"
00007 #include "DW1000.h"
00008 
00009 #define TIMEUNITS_TO_US       (1/(128*499.2))               // conversion between the decawave timeunits (ca 15.65ps) to microseconds.
00010 #define US_TO_TIMEUNITS       (128*499.2)                   // conversion between microseconds to the decawave timeunits (ca 15.65ps).
00011 #define MMRANGING_2POWER40          1099511627776               // decimal value of 2^40 to correct timeroverflow between timestamps
00012 
00013 
00014 
00015 //Predefined delay for the critical answers in the ranging algorithm
00016 //HAS TO BE BIGGER THAN THE PROCESSING TIME OF THE FRAME ON THE NODE
00017 #define ANSWER_DELAY_US             2500                                    //2500 works for 110kbps, 900 for 6.8Mbps
00018 #define ANSWER_DELAY_TIMEUNITS      ANSWER_DELAY_US * (128*499.2)
00019 
00020 class MM2WayRanging {
00021 
00022 public:
00023     MM2WayRanging(DW1000& DW);
00024 
00025     void requestRanging(uint8_t destination);
00026     void requestRangingAll();
00027 
00028 
00029 
00030     //TODO: Better capsulation on those?
00031     bool isAnchor;
00032     uint8_t address; // Identifies the nodes as source and destination in rangingframes
00033 
00034     //TODO: Make those PRIVATE!
00035     float roundtriptimes[10]; // Array containing the round trip times to the anchors or the timeout which occured
00036     float distances[10]; // Array containing the finally calculated Distances to the anchors
00037 
00038     bool overflow;              // TRUE if counter overflows while ranging
00039 
00040 private:
00041 
00042 
00043     DW1000& dw;
00044     Timer LocalTimer;
00045 
00046     void callbackRX();
00047     void callbackTX();
00048     void sendPingFrame(uint8_t destination);
00049     void sendDelayedAnswer(uint8_t destination, uint8_t type, uint64_t rxTimestamp);
00050     void sendTransferFrame(uint8_t destination, int timestamp);
00051 
00052     inline float calibratedDistance(uint8_t destination);
00053 
00054     /**
00055      * These two functions correct the timestamps if the counter had an overflow between measurements
00056      */
00057     void correctReceiverTimestamps(uint8_t source);
00058     void correctSenderTimestamps(uint8_t source);
00059 
00060     int timediffRec;
00061     int timediffSend;
00062 
00063     enum FrameType{
00064         PING=1,
00065         ANCHOR_RESPONSE,
00066         BEACON_RESPONSE,
00067         TRANSFER_FRAME,
00068         DISTANCES_FRAME
00069     };
00070 
00071     //the packed attribute makes sure the types only use their respective size in memory (8 bit for uint8_t), otherwise they would always use 32 bit
00072     //IT IS A GCC SPECIFIC DIRECTIVE
00073     struct __attribute__((packed, aligned(1))) RangingFrame {
00074         uint8_t source;
00075         uint8_t destination;
00076         uint8_t type;
00077     };
00078 
00079     struct __attribute__((packed, aligned(1))) ExtendedRangingFrame : RangingFrame{
00080         int signedTime;
00081     };
00082 
00083 
00084     RangingFrame rangingFrame;                  // buffer in class for sending a frame (not made locally because then we can recall in the interrupt what was sent)
00085     ExtendedRangingFrame transferFrame;
00086     ExtendedRangingFrame receivedFrame;
00087     uint64_t rxTimestamp;
00088     uint64_t senderTimestamps[10][3];
00089     uint64_t receiverTimestamps[10][3];
00090     bool acknowledgement[10];                   // flag to indicate if ranging has succeeded
00091     uint32_t tofs[10];                          // Array containing time of flights for each node (index is address of node)
00092 
00093 };
00094 
00095 #endif