Line data    Source code

       1             : /*
       2             :    This program is free software: you can redistribute it and/or modify
       3             :    it under the terms of the GNU General Public License as published by
       4             :    the Free Software Foundation, either version 3 of the License, or
       5             :    (at your option) any later version.
       6             : 
       7             :    This program is distributed in the hope that it will be useful,
       8             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
       9             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      10             :    GNU General Public License for more details.
      11             : 
      12             :    You should have received a copy of the GNU General Public License
      13             :    along with this program.  If not, see <http://www.gnu.org/licenses/>.
      14             :  */
      15             : 
      16             : #include "AP_RangeFinder_Benewake.h"
      17             : 
      18             : #if AP_RANGEFINDER_BENEWAKE_ENABLED
      19             : 
      20             : #include <AP_HAL/AP_HAL.h>
      21             : #include <AP_HAL/utility/sparse-endian.h>
      22             : 
      23             : #include <ctype.h>
      24             : 
      25             : extern const AP_HAL::HAL& hal;
      26             : 
      27             : #define BENEWAKE_FRAME_HEADER 0x59
      28             : #define BENEWAKE_FRAME_LENGTH 9
      29             : #define BENEWAKE_DIST_MAX_CM 32768
      30             : #define BENEWAKE_OUT_OF_RANGE_ADD 1.00  // metres
      31             : 
      32             : // format of serial packets received from benewake lidar
      33             : // Model       | Byte 0-1  | Byte 2 | Byte 3 | Byte 4     | Byte 5     | Byte 6     | Byte 7         | Byte 8
      34             : // ------------+-----------+--------+--------+------------+------------+------------+----------------+---------
      35             : // TFmini      | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | dist mode* | reserved       | Checksum
      36             : // TF02        | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | SIG*       | Exposure Time* | Checksum
      37             : // TF-Nova     | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | Temp       | Confidence*    | Checksum
      38             : // ------------+-----------+--------+--------+------------+------------+------------+----------------+---------
      39             : // TFmini-S    | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | Temp_L     | Temp_H         | Checksum
      40             : // TFmini-plus | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | Temp_L     | Temp_H         | Checksum
      41             : // TF02-Pro    | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | Temp_L     | Temp_H         | Checksum
      42             : // TFS20-L     | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | Temp_L     | Temp_H         | Checksum
      43             : // TF-Luna     | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | Temp_L     | Temp_H         | Checksum
      44             : // TF03        | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | reserved   | reserved       | Checksum
      45             : // TF350       | 0x59 0x59 | Dist_L | Dist_H | Strength_L | Strength_H | reserved   | reserved       | Checksum
      46             : //
      47             : // Notes:
      48             : // TFmini (discontinued) : Byte 6 : Distance mode is 0x02 for short distance (mm), 0x07 for long distance (cm)
      49             : // TF02 (discontinued) : Byte 6 : SIG byte is reliability in 8 levels, 7 & 8 means reliable
      50             : // TF02 (discontinued) : Byte 7 : Exposure Time in two levels 0x03 and 0x06
      51             : // TF-Nova : Byte 7 : Confidence from 0 ~ 100 (100 being highest confidence)
      52             : //
      53             : // Strength values per model:
      54             : // TFmini: No documentation
      55             : // TF02: 0 ~ 3000, reliable if value >=20 and <= 2000
      56             : // TF-Nova: No documentation
      57             : // TFmini-S: 0 ~ 65535. reliable if value >=100 and <65535, 65535 (-1) means signal strength saturation (bad)
      58             : // TFmini-plus: 0 ~ 65535. reliable if value >=100 and <65535, 65535 (-1) means signal strength saturation (bad)
      59             : // TF02-Pro: 0 ~ 65535, no documentation
      60             : // TFS20-L: 0 ~ 65535, no documentation
      61             : // TF-Luna: 0 ~ 65535. reliable if value >=100 and <65535, 65535 (-1) means signal strength saturation (bad)
      62             : // TF03: 0 ~ 3500, reliable if >=40 ~ 1200.  if high reflectivity object will be 1500
      63             : // TF350: 0 ~ 3500, reliable if >=40 ~ 1200.  if high reflectivity object will be 1500
      64             : 
      65             : // distance returned in reading_m, signal_ok is set to true if sensor reports a strong signal
      66        5809 : bool AP_RangeFinder_Benewake::get_reading(float &reading_m)
      67             : {
      68        5809 :     if (uart == nullptr) {
      69           0 :         return false;
      70             :     }
      71             : 
      72        5809 :     float sum_cm = 0;
      73        5809 :     uint16_t count = 0;
      74        5809 :     uint16_t count_out_of_range = 0;
      75             : 
      76             :     // read any available lines from the lidar
      77       19093 :     for (auto j=0; j<8192; j++) {
      78             :         uint8_t c;
      79       19093 :         if (!uart->read(c)) {
      80        5809 :             break;
      81             :         }
      82             :         // if buffer is empty and this byte is 0x59, add to buffer
      83       13284 :         if (linebuf_len == 0) {
      84        1476 :             if (c == BENEWAKE_FRAME_HEADER) {
      85        1476 :                 linebuf[linebuf_len++] = c;
      86             :             }
      87       11808 :         } else if (linebuf_len == 1) {
      88             :             // if buffer has 1 element and this byte is 0x59, add it to buffer
      89             :             // if not clear the buffer
      90        1476 :             if (c == BENEWAKE_FRAME_HEADER) {
      91        1476 :                 linebuf[linebuf_len++] = c;
      92             :             } else {
      93           0 :                 linebuf_len = 0;
      94             :             }
      95             :         } else {
      96             :             // add character to buffer
      97       10332 :             linebuf[linebuf_len++] = c;
      98             :             // if buffer now has 9 items try to decode it
      99       10332 :             if (linebuf_len == BENEWAKE_FRAME_LENGTH) {
     100             :                 // calculate checksum
     101        1476 :                 uint8_t checksum = 0;
     102       13284 :                 for (uint8_t i=0; i<BENEWAKE_FRAME_LENGTH-1; i++) {
     103       11808 :                     checksum += linebuf[i];
     104             :                 }
     105             :                 // if checksum matches extract contents
     106        1476 :                 if (checksum == linebuf[BENEWAKE_FRAME_LENGTH-1]) {
     107             :                     // calculate distance
     108        1476 :                     uint16_t dist = ((uint16_t)linebuf[3] << 8) | linebuf[2];
     109        1476 :                     if (dist >= BENEWAKE_DIST_MAX_CM || dist == uint16_t(model_dist_max_cm())) {
     110             :                         // this reading is out of range. Note that we
     111             :                         // consider getting exactly the model dist max
     112             :                         // is out of range. This fixes an issue with
     113             :                         // the TF03 which can give exactly 18000 cm
     114             :                         // when out of range
     115           0 :                         count_out_of_range++;
     116        1476 :                     } else if (!has_signal_byte()) {
     117             :                         // no signal byte so can immediately add distance to sum
     118         689 :                         sum_cm += dist;
     119         689 :                         count++;
     120             :                     } else {
     121             :                         // TF02 provides signal reliability (good = 7 or 8)
     122         787 :                         if (linebuf[6] >= 7) {
     123             :                             // add distance to sum
     124         787 :                             sum_cm += dist;
     125         787 :                             count++;
     126             :                         } else {
     127             :                             // this reading is out of range
     128           0 :                             count_out_of_range++;
     129             :                         }
     130             :                     }
     131             :                 }
     132             :                 // clear buffer
     133        1476 :                 linebuf_len = 0;
     134             :             }
     135             :         }
     136             :     }
     137             : 
     138        5809 :     if (count > 0) {
     139             :         // return average distance of readings
     140        1459 :         reading_m = (sum_cm * 0.01f) / count;
     141        1459 :         return true;
     142             :     }
     143             : 
     144        4350 :     if (count_out_of_range > 0) {
     145             :         // if only out of range readings return larger of
     146             :         // driver defined maximum range for the model and user defined max range + 1m
     147           0 :         reading_m = MAX(model_dist_max_cm() * 0.01, max_distance() + BENEWAKE_OUT_OF_RANGE_ADD);
     148           0 :         return true;
     149             :     }
     150             : 
     151             :     // no readings so return false
     152        4350 :     return false;
     153             : }
     154             : 
     155             : #endif  // AP_RANGEFINDER_BENEWAKE_ENABLED