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             : /*
      17             :    driver for UPixel UPFLOW optical flow sensor
      18             : 
      19             :    UPFLOW serial packet description
      20             :    byte0: header0 (0xFE)
      21             :    byte1: header1 (0x0A)
      22             :    byte2: x-motion low byte;
      23             :    byte3: x-motion high byte;
      24             :    byte4: y-motion low byte;
      25             :    byte5: y-motion high byte;
      26             :    byte6: dt low byte;
      27             :    byte7: dt high byte;
      28             :    byte8: reserved;
      29             :    byte9: reserved;
      30             :    byte10: surface quality
      31             :    byte11: hardware version
      32             :    byte12:checksum
      33             :    byte13:footer (0x55)
      34             :  */
      35             : 
      36             : #include "AP_OpticalFlow_UPFLOW.h"
      37             : 
      38             : #if AP_OPTICALFLOW_UPFLOW_ENABLED
      39             : 
      40             : #include <AP_HAL/AP_HAL.h>
      41             : #include <AP_AHRS/AP_AHRS.h>
      42             : #include <AP_SerialManager/AP_SerialManager.h>
      43             : #include <utility>
      44             : #include "AP_OpticalFlow.h"
      45             : #include <stdio.h>
      46             : 
      47             : #define UPFLOW_HEADER0         (uint8_t)0xFE
      48             : #define UPFLOW_HEADER1         (uint8_t)0x0A
      49             : #define UPFLOW_FOOTER         (uint8_t)0x55
      50             : #define UPFLOW_PIXEL_SCALING         (1e-4)
      51             : #define UPFLOW_TIMEOUT_SEC         0.3f
      52             : 
      53             : extern const AP_HAL::HAL& hal;
      54             : 
      55             : // constructor
      56           0 : AP_OpticalFlow_UPFLOW::AP_OpticalFlow_UPFLOW(AP_OpticalFlow &_frontend, AP_HAL::UARTDriver *_uart) :
      57             :     OpticalFlow_backend(_frontend),
      58           0 :     uart(_uart)
      59             : {
      60           0 : }
      61             : 
      62             : // detect the device
      63           0 : AP_OpticalFlow_UPFLOW *AP_OpticalFlow_UPFLOW::detect(AP_OpticalFlow &_frontend)
      64             : {
      65           0 :     AP_SerialManager *serial_manager = AP::serialmanager().get_singleton();
      66           0 :     if (serial_manager == nullptr) {
      67           0 :         return nullptr;
      68             :     }
      69             : 
      70             :     // look for first serial driver with protocol defined as OpticalFlow
      71           0 :     AP_HAL::UARTDriver *uart = serial_manager->find_serial(AP_SerialManager::SerialProtocol_OpticalFlow, 0);
      72           0 :     if (uart == nullptr) {
      73           0 :         return nullptr;
      74             :     }
      75             : 
      76             :     // we have found a serial port so use it
      77           0 :     AP_OpticalFlow_UPFLOW *sensor = NEW_NOTHROW AP_OpticalFlow_UPFLOW(_frontend, uart);
      78           0 :     return sensor;
      79             : }
      80             : 
      81             : // initialise the sensor
      82           0 : void AP_OpticalFlow_UPFLOW::init()
      83             : {
      84             :     // sanity check uart
      85           0 :     if (uart == nullptr) {
      86           0 :         return;
      87             :     }
      88             :     // open serial port with baud rate of 19200
      89           0 :     uart->begin(19200);
      90             : }
      91             : 
      92             : // read latest values from sensor and fill in x,y and totals.
      93           0 : void AP_OpticalFlow_UPFLOW::update(void)
      94             : {
      95             :     // sanity check uart
      96           0 :     if (uart == nullptr) {
      97           0 :         return;
      98             :     }
      99             : 
     100             :     // record gyro values as long as they are being used
     101             :     // the sanity check of dt below ensures old gyro values are not used
     102           0 :     if (gyro_sum_count >= 1000) {
     103           0 :         gyro_sum.zero();
     104           0 :         gyro_sum_count = 0;
     105             :     }
     106           0 :     const Vector3f& gyro = AP::ahrs().get_gyro();
     107           0 :     gyro_sum.x += gyro.x;
     108           0 :     gyro_sum.y += gyro.y;
     109           0 :     gyro_sum_count++;
     110             : 
     111             : 
     112           0 :     bool phrased = false;
     113             :     // read any available characters in the serial buffer
     114           0 :     uint32_t nbytes = MIN(uart->available(), 1024u);
     115           0 :     while (nbytes-- > 0) {
     116           0 :         int16_t r = uart->read();
     117           0 :         if (r < 0) {
     118           0 :             break;
     119             :         }
     120           0 :         uint8_t c = (uint8_t)r;
     121           0 :         if (recv_count == 0) {
     122             :             //Header0
     123           0 :             if (c == UPFLOW_HEADER0) {
     124           0 :                 recv_count++;
     125           0 :                 sum = 0;
     126             :             }
     127           0 :         } else if (recv_count == 1) {
     128             :             //Header1
     129           0 :             if (c != UPFLOW_HEADER1) {
     130           0 :                 recv_count = 0;
     131             :             } else {
     132           0 :                 recv_count++;
     133             :             }
     134           0 :         } else if (recv_count < 12) {
     135             :             //actual data
     136           0 :             ((uint8_t*)&updata)[recv_count - 2] = c;
     137           0 :             sum ^= c;
     138           0 :             recv_count++;
     139           0 :         } else if (recv_count == 12) {
     140             :             //checksum
     141           0 :             if (sum != c) {
     142           0 :                 recv_count = 0;
     143             :             } else {
     144           0 :                 recv_count++;
     145             :             }
     146             :         } else {        //footer
     147           0 :             if (c == UPFLOW_FOOTER) {
     148           0 :                 phrased=true;
     149             :             }
     150           0 :             recv_count = 0;
     151             :         }
     152             :     }
     153             : 
     154             :     // return without updating state if no readings
     155           0 :     if (phrased == false) {
     156           0 :         return;
     157             :     }
     158             : 
     159           0 :     struct AP_OpticalFlow::OpticalFlow_state state {};
     160             : 
     161           0 :     state.surface_quality = updata.quality;
     162             : 
     163           0 :     float dt = updata.integration_timespan * 1.0e-6;
     164             : 
     165             :     // sanity check dt
     166           0 :     if (is_positive(dt) && (dt < UPFLOW_TIMEOUT_SEC)) {
     167             :         // calculate flow values
     168           0 :         const Vector2f flowScaler = _flowScaler();
     169           0 :         Vector2f flowScaleFactor = Vector2f(1.0f, 1.0f) +  flowScaler * 0.001f;
     170             : 
     171             :         // copy flow rates to state structure
     172           0 :         state.flowRate = Vector2f((float)(-updata.flow_x_integral) * flowScaleFactor.x,
     173           0 :                                   (float)(-updata.flow_y_integral) * flowScaleFactor.y);
     174           0 :         state.flowRate *= UPFLOW_PIXEL_SCALING / dt;
     175             : 
     176             :         // copy average body rate to state structure
     177           0 :         state.bodyRate = Vector2f{gyro_sum.x / gyro_sum_count, gyro_sum.y / gyro_sum_count};
     178             : 
     179             :         // we only apply yaw to flowRate as body rate comes from AHRS
     180           0 :         _applyYaw(state.flowRate);
     181             :     } else {
     182             :         // first frame received in some time so cannot calculate flow values
     183           0 :         state.flowRate.zero();
     184           0 :         state.bodyRate.zero();
     185             :     }
     186             : 
     187           0 :     _update_frontend(state);
     188             : 
     189             :     // reset gyro sum
     190           0 :     gyro_sum.zero();
     191           0 :     gyro_sum_count = 0;
     192             : }
     193             : 
     194             : #endif  // AP_OPTICALFLOW_UPFLOW_ENABLED