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             : Written with reference to the PX4 driver written by Roman Dvorak <[email protected]>
      16             : 
      17             : */
      18             : 
      19             : #include "AP_TemperatureSensor_SHT3x.h"
      20             : 
      21             : #if AP_TEMPERATURE_SENSOR_SHT3X_ENABLED
      22             : #include <utility>
      23             : #include <stdio.h>
      24             : #include <AP_HAL/I2CDevice.h>
      25             : #include <AP_Math/AP_Math.h>
      26             : 
      27             : #include <GCS_MAVLink/GCS.h>
      28             : 
      29             : extern const AP_HAL::HAL &hal;
      30             : 
      31           9 : void AP_TemperatureSensor_SHT3x::init()
      32             : {
      33           9 :     constexpr char name[] = "SHT3x";
      34             :     (void)name;  // sometimes this is unused (e.g. HAL_GCS_ENABLED false)
      35             : 
      36           9 :     _dev = hal.i2c_mgr->get_device_ptr(_params.bus, _params.bus_address);
      37           9 :     if (!_dev) {
      38           0 :         GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "%s device is null!", name);
      39           6 :         return;
      40             :     }
      41             : 
      42           9 :     WITH_SEMAPHORE(_dev->get_semaphore());
      43             : 
      44           9 :     _dev->set_retries(10);
      45             : 
      46             :     // read serial number
      47             :     static const uint8_t read_sn_cmd[2] { 0x37, 0x80 };
      48             :     uint8_t sn[6];
      49           9 :     if (!_dev->transfer(read_sn_cmd, ARRAY_SIZE(read_sn_cmd), sn, ARRAY_SIZE(sn))) {
      50           6 :         GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "%s read sn failed", name);
      51           6 :         return;
      52             :     }
      53             :     // emit serial number, more of confirmation we have the sensor:
      54           3 :     GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "SHT3x: SN%x%x%x%x%x%x", sn[0], sn[1], sn[2], sn[3], sn[4], sn[5]);
      55             : 
      56             :     // reset
      57             :     static const uint8_t soft_reset_cmd[2] { 0x30, 0xA2 };  // page 12
      58           3 :     if (!_dev->transfer(soft_reset_cmd, ARRAY_SIZE(soft_reset_cmd), nullptr, 0)) {
      59           0 :         GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "%s reset failed", name);
      60           0 :         return;
      61             :     }
      62             : 
      63           3 :     hal.scheduler->delay(4);
      64             : 
      65           3 :     start_next_sample();
      66             : 
      67             :     // lower retries for run
      68           3 :     _dev->set_retries(3);
      69             : 
      70             :     /* Request 20Hz update */
      71           3 :     _dev->register_periodic_callback(50 * AP_USEC_PER_MSEC,
      72             :                                      FUNCTOR_BIND_MEMBER(&AP_TemperatureSensor_SHT3x::_timer, void));
      73           9 : }
      74             : 
      75         847 : bool AP_TemperatureSensor_SHT3x::read_measurements(uint16_t &temp, uint16_t &humidity) const
      76             : {
      77             :     uint8_t val[6];
      78         847 :     if (!_dev->transfer(nullptr, 1, val, ARRAY_SIZE(val))) {
      79           0 :         return 0;
      80             :     }
      81             : 
      82         847 :     if (val[2] != crc8_generic(&val[0], 2, 0x31, 0xff)) {
      83             :         // temperature CRC is incorrect
      84           0 :         return false;
      85             :     }
      86             : 
      87         847 :     if (val[5] != crc8_generic(&val[3], 2, 0x31, 0xff)) {
      88             :         // humidity CRC is incorrect
      89           0 :         return false;
      90             :     }
      91             : 
      92         847 :     temp = val[0] << 8 | val[1];
      93         847 :     humidity = val[3] << 8 | val[4];
      94         847 :     return true;
      95             : }
      96             : 
      97         847 : void AP_TemperatureSensor_SHT3x::_timer(void)
      98             : {
      99             :     uint16_t encoded_temp;
     100             :     uint16_t encoded_humidity;
     101         847 :     if (read_measurements(encoded_temp, encoded_humidity)) {
     102         847 :         const float temp = -45 + 175 * (encoded_temp/65535.0);
     103         847 :         set_temperature(temp);
     104             :     }
     105             : 
     106         847 :     start_next_sample();
     107         847 : }
     108             : 
     109         850 : void AP_TemperatureSensor_SHT3x::start_next_sample()
     110             : {
     111             :     static const uint8_t start_measurement_command[2] { 0x2c, 0x06 };
     112         850 :     _dev->transfer(start_measurement_command, ARRAY_SIZE(start_measurement_command), nullptr, 0);
     113         850 : }
     114             : 
     115             : #endif // AP_TEMPERATURE_SENSOR_SHT3X_ENABLED