AP_TemperatureSensor: add support for SHT3x-DIS temperature sensor

Author: peterbarker

libraries/AP_TemperatureSensor/AP_TemperatureSensor.cpp

@@ -33,6 +33,7 @@
 #include "AP_TemperatureSensor_Analog.h"
 #include "AP_TemperatureSensor_DroneCAN.h"
 #include "AP_TemperatureSensor_MLX90614.h"
+#include "AP_TemperatureSensor_SHT3x.h"
 
 #include <AP_Logger/AP_Logger.h>
 #include <AP_Vehicle/AP_Vehicle_Type.h>
@@ -192,6 +193,11 @@ void AP_TemperatureSensor::init()
                 drivers[instance] = NEW_NOTHROW AP_TemperatureSensor_MAX31865(*this, _state[instance], _params[instance]);
                 break;
 #endif
+#if AP_TEMPERATURE_SENSOR_SHT3X_ENABLED
+            case AP_TemperatureSensor_Params::Type::SHT3x:
+                drivers[instance] = NEW_NOTHROW AP_TemperatureSensor_SHT3x(*this, _state[instance], _params[instance]);
+                break;
+#endif  // AP_TEMPERATURE_SENSOR_SHT3X_ENABLED
 #if AP_TEMPERATURE_SENSOR_TSYS03_ENABLED
             case AP_TemperatureSensor_Params::Type::TSYS03:
                 drivers[instance] = NEW_NOTHROW AP_TemperatureSensor_TSYS03(*this, _state[instance], _params[instance]);

libraries/AP_TemperatureSensor/AP_TemperatureSensor_Params.cpp

@@ -34,7 +34,7 @@ const AP_Param::GroupInfo AP_TemperatureSensor_Params::var_info[] = {
     // @Param: TYPE
     // @DisplayName: Temperature Sensor Type
     // @Description: Enables temperature sensors
-    // @Values: 0:Disabled, 1:TSYS01, 2:MCP9600, 3:MAX31865, 4:TSYS03, 5:Analog, 6:DroneCAN, 7:MLX90614
+    // @Values: 0:Disabled, 1:TSYS01, 2:MCP9600, 3:MAX31865, 4:TSYS03, 5:Analog, 6:DroneCAN, 7:MLX90614, 8:SHT3x
     // @User: Standard
     // @RebootRequired: True
     AP_GROUPINFO_FLAGS("TYPE", 1, AP_TemperatureSensor_Params, type, (float)Type::NONE, AP_PARAM_FLAG_ENABLE),

libraries/AP_TemperatureSensor/AP_TemperatureSensor_Params.h

@@ -35,6 +35,7 @@ class AP_TemperatureSensor_Params {
         ANALOG                      = 5,
         DRONECAN                    = 6,
         MLX90614                    = 7,
+        SHT3x                       = 8,
     };
 
     // option to map to another system component

libraries/AP_TemperatureSensor/AP_TemperatureSensor_SHT3x.cpp

@@ -0,0 +1,115 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Written with reference to the PX4 driver written by Roman Dvorak <dvorakroman@thunderfly.cz>
+
+*/
+
+#include "AP_TemperatureSensor_SHT3x.h"
+
+#if AP_TEMPERATURE_SENSOR_SHT3X_ENABLED
+#include <utility>
+#include <stdio.h>
+#include <AP_HAL/I2CDevice.h>
+#include <AP_Math/AP_Math.h>
+
+#include <GCS_MAVLink/GCS.h>
+
+extern const AP_HAL::HAL &hal;
+
+void AP_TemperatureSensor_SHT3x::init()
+{
+    constexpr char name[] = "SHT3x";
+    (void)name;  // sometimes this is unused (e.g. HAL_GCS_ENABLED false)
+
+    _dev = std::move(hal.i2c_mgr->get_device(_params.bus, _params.bus_address));
+    if (!_dev) {
+        GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "%s device is null!", name);
+        return;
+    }
+
+    WITH_SEMAPHORE(_dev->get_semaphore());
+
+    _dev->set_retries(10);
+
+    // read serial number
+    static const uint8_t read_sn_cmd[2] { 0x37, 0x80 };
+    uint8_t sn[6];
+    if (!_dev->transfer(read_sn_cmd, ARRAY_SIZE(read_sn_cmd), sn, ARRAY_SIZE(sn))) {
+        GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "%s read sn failed", name);
+        return;
+    }
+    // emit serial number, more of confirmation we have the sensor:
+    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]);
+
+    // reset
+    static const uint8_t soft_reset_cmd[2] { 0x30, 0xA2 };  // page 12
+    if (!_dev->transfer(soft_reset_cmd, ARRAY_SIZE(soft_reset_cmd), nullptr, 0)) {
+        GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "%s reset failed", name);
+        return;
+    }
+
+    hal.scheduler->delay(4);
+
+    start_next_sample();
+
+    // lower retries for run
+    _dev->set_retries(3);
+
+    /* Request 20Hz update */
+    _dev->register_periodic_callback(50 * AP_USEC_PER_MSEC,
+                                     FUNCTOR_BIND_MEMBER(&AP_TemperatureSensor_SHT3x::_timer, void));
+}
+
+bool AP_TemperatureSensor_SHT3x::read_measurements(uint16_t &temp, uint16_t &humidity) const
+{
+    uint8_t val[6];
+    if (!_dev->transfer(nullptr, 1, val, ARRAY_SIZE(val))) {
+        return 0;
+    }
+
+    if (val[2] != crc8_generic(&val[0], 2, 0x31, 0xff)) {
+        // temperature CRC is incorrect
+        return false;
+    }
+
+    if (val[5] != crc8_generic(&val[3], 2, 0x31, 0xff)) {
+        // humidity CRC is incorrect
+        return false;
+    }
+
+    temp = val[0] << 8 | val[1];
+    humidity = val[3] << 8 | val[4];
+    return true;
+}
+
+void AP_TemperatureSensor_SHT3x::_timer(void)
+{
+    uint16_t encoded_temp;
+    uint16_t encoded_humidity;
+    if (read_measurements(encoded_temp, encoded_humidity)) {
+        const float temp = -45 + 175 * (encoded_temp/65535.0);
+        set_temperature(temp);
+    }
+
+    start_next_sample();
+}
+
+void AP_TemperatureSensor_SHT3x::start_next_sample()
+{
+    static const uint8_t start_measurement_command[2] { 0x2c, 0x06 };
+    _dev->transfer(start_measurement_command, ARRAY_SIZE(start_measurement_command), nullptr, 0);
+}
+
+#endif // AP_TEMPERATURE_SENSOR_SHT3X_ENABLED

libraries/AP_TemperatureSensor/AP_TemperatureSensor_SHT3x.h

@@ -0,0 +1,77 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * I2C driver for Sensiron SHT3x digital temperature sensor
+
+ https://sensirion.com/media/documents/213E6A3B/63A5A569/Datasheet_SHT3x_DIS.pdf
+
+
+ Testing:
+
+pbarker@fx:~$ cat /tmp/extra.hwdef
+define AP_TEMPERATURE_SENSOR_ENABLED 1
+define AP_TEMPERATURE_SENSOR_BACKEND_DEFAULT_ENABLED 1
+pbarker@fx:~$ ./waf configure --board=CubeOrange --extra-hwdef=/tmp/extra.hwdef
+pbarker@fx:~/rc/ardupilot(pr/SHT3x)$ ./waf rover --upload
+
+# when plugging into I2C1 on a CubeOrange:
+param set TEMP1_TYPE 8
+param set TEMP1_BUS 0
+
+this is bad:
+AP: SHT3x reset failed
+AP: SHT3x: SN1841CC41FC5
+
+param set TEMP_LOG 1
+param set LOG_DISARMED 1
+...
+param set LOG_DISARMED 0
+
+Download log and check for temperatures
+
+*/
+
+#pragma once
+
+#include "AP_TemperatureSensor_config.h"
+
+#if AP_TEMPERATURE_SENSOR_SHT3X_ENABLED
+
+#include "AP_TemperatureSensor_Backend.h"
+
+class AP_TemperatureSensor_SHT3x : public AP_TemperatureSensor_Backend {
+
+    using AP_TemperatureSensor_Backend::AP_TemperatureSensor_Backend;
+
+public:
+    __INITFUNC__ void init(void) override;
+
+    void update() override {};
+
+private:
+    // reset device
+    bool reset(void) const;
+
+    // prod device to start preparing a measurement:
+    void start_next_sample();
+    // read measurements from device:
+    bool read_measurements(uint16_t &temp, uint16_t &humidity) const;
+
+    // update the temperature, called at 20Hz
+    void _timer(void);
+
+};
+#endif // AP_TEMPERATURE_SENSOR_SHT3X_ENABLED

libraries/AP_TemperatureSensor/AP_TemperatureSensor_config.h

@@ -39,6 +39,10 @@
     #define AP_TEMPERATURE_SENSOR_MLX90614_ENABLED AP_TEMPERATURE_SENSOR_ENABLED
 #endif
 
+#ifndef AP_TEMPERATURE_SENSOR_SHT3X_ENABLED
+#define AP_TEMPERATURE_SENSOR_SHT3X_ENABLED AP_TEMPERATURE_SENSOR_ENABLED
+#endif  // AP_TEMPERATURE_SENSOR_SHT3X_ENABLED
+
 // maximum number of Temperature Sensors
 #ifndef AP_TEMPERATURE_SENSOR_MAX_INSTANCES
 #define AP_TEMPERATURE_SENSOR_MAX_INSTANCES             3