AP_TemperatureSensor: add driver for MAX31865

libraries/AP_TemperatureSensor/AP_TemperatureSensor.cpp

@@ -26,6 +26,7 @@
 
 #include "AP_TemperatureSensor_TSYS01.h"
 #include "AP_TemperatureSensor_MCP9600.h"
+#include "AP_TemperatureSensor_MAX31865.h"
 
 #include <AP_Logger/AP_Logger.h>
 #include <AP_Vehicle/AP_Vehicle_Type.h>
@@ -134,6 +135,11 @@ void AP_TemperatureSensor::init()
             case AP_TemperatureSensor_Params::Type::MCP9600:
                 drivers[instance] = new AP_TemperatureSensor_MCP9600(*this, _state[instance], _params[instance]);
                 break;
+#endif
+#if AP_TEMPERATURE_SENSOR_MAX31865_ENABLED
+            case AP_TemperatureSensor_Params::Type::MAX31865:
+                drivers[instance] = new AP_TemperatureSensor_MAX31865(*this, _state[instance], _params[instance]);
+                break;
 #endif
             case AP_TemperatureSensor_Params::Type::NONE:
             default:

libraries/AP_TemperatureSensor/AP_TemperatureSensor.h

@@ -24,12 +24,14 @@
 class AP_TemperatureSensor_Backend;
 class AP_TemperatureSensor_TSYS01;
 class AP_TemperatureSensor_MCP9600;
+class AP_TemperatureSensor_MAX31865;
 
 class AP_TemperatureSensor
 {
     friend class AP_TemperatureSensor_Backend;
     friend class AP_TemperatureSensor_TSYS01;
     friend class AP_TemperatureSensor_MCP9600;
+    friend class AP_TemperatureSensor_MAX31865;
 
 public:
 

libraries/AP_TemperatureSensor/AP_TemperatureSensor_MAX31865.cpp

@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2023 Kraus Hamdani Aerospace Inc. All rights reserved.
+ *
+ * This file 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 file 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/>.
+ *
+ * Code by Tom Pittenger
+ */
+/*
+    Implements SPI driver for MAX31865 digital RTD Temperature converter
+*/
+
+#include "AP_TemperatureSensor_MAX31865.h"
+
+#if AP_TEMPERATURE_SENSOR_MAX31865_ENABLED
+#include <stdio.h>
+#include <AP_Math/AP_Math.h>
+#include <AP_HAL/utility/sparse-endian.h>
+
+extern const AP_HAL::HAL &hal;
+
+#define MAX31865_REG_WRITE_ADDR_OFFSET      0x80
+
+
+#define MAX31865_REG_CONFIG_READ            0x00
+#define MAX31865_REG_CONFIG_WRITE           (MAX31865_REG_CONFIG_READ | MAX31865_REG_WRITE_ADDR_OFFSET)
+#define MAX31865_REG_DATA_MSB               0x01
+#define MAX31865_REG_DATA_LSB               0x02
+#define MAX31865_REG_HIGH_FAULT_THRESH_MSB  0x03
+#define MAX31865_REG_HIGH_FAULT_THRESH_LSB  0x04
+#define MAX31865_REG_LOW_FAULT_THRESH_MSB   0x05
+#define MAX31865_REG_LOW_FAULT_THRESH_LSB   0x06
+#define MAX31865_REG_FAULT_STATUS_READ      0x07
+#define MAX31865_REG_FAULT_STATUS_WRITE     (MAX31865_REG_FAULT_STATUS_READ | MAX31865_REG_WRITE_ADDR_OFFSET)
+
+
+// Vbias = ON (must be on for automatic mode)
+// Conversion mode: Auto
+// Fault Status: 1set 1 to Clear all latched faults
+#define MAX31865_CONFIG_VALUE               (0b11000010)
+
+#define MAX31865_DEBUGGING 0
+
+#if MAX31865_DEBUGGING
+#ifdef HAL_BUILD_AP_PERIPH
+    extern "C" {
+    void can_printf(const char *fmt, ...);
+    }
+    //# define Debug(fmt, args ...)  do { can_printf("%s:%d: " fmt "\n", __FUNCTION__, __LINE__, ## args); hal.scheduler->delay(1); } while(0)
+      #  define Debug(fmt, args ...)  do { can_printf(fmt, ## args); } while(0)
+#else
+ # define Debug(fmt, args ...)  do {hal.console->printf("%s:%d: " fmt "\n", __FUNCTION__, __LINE__, ## args); hal.scheduler->delay(1); } while(0)
+ #endif // HAL_BUILD_AP_PERIPH
+#else
+ # define Debug(fmt, args ...)
+#endif // MAX31865_DEBUGGING
+
+
+void AP_TemperatureSensor_MAX31865::init()
+{
+    if (_dev) {
+        return;
+    }
+
+    // also look for "max31865_n" where n is the addr param.
+    char name[12] = "max31865";
+    if (_params.bus_address > 0 && _params.bus_address <= 9) {
+        name[8] = '_';
+        name[9] = '0' + _params.bus_address; // convert bus_address to ascii
+        name[10] = 0;
+    }
+
+    _dev = std::move(hal.spi->get_device(name));
+    if (!_dev) {
+        return;
+    }
+
+    WITH_SEMAPHORE(_dev->get_semaphore());
+
+    _dev->set_speed(AP_HAL::Device::SPEED_LOW);
+
+    _dev->write_register(MAX31865_REG_CONFIG_WRITE, MAX31865_CONFIG_VALUE);
+
+    _dev->set_speed(AP_HAL::Device::SPEED_HIGH);
+
+    /* Request 10Hz update */
+    _dev->register_periodic_callback(100 * AP_USEC_PER_MSEC,
+                                     FUNCTOR_BIND_MEMBER(&AP_TemperatureSensor_MAX31865::thread_tick, void));
+}
+
+void AP_TemperatureSensor_MAX31865::thread_tick()
+{
+    uint16_t raw_data;
+    if (!_dev->read_registers(MAX31865_REG_DATA_MSB, (uint8_t *)&raw_data, sizeof(raw_data))) {
+        return;
+    }
+
+    // 16bit byte swap
+     const uint16_t data = htobe16(raw_data);
+
+    // fault is LSB bit, temperature data is upper 15 bits
+    const bool is_fault = (data & 0x0001) != 0;
+    const uint16_t data_temperature = data >> 1;
+
+    if (is_fault) {
+#if MAX31865_DEBUGGING
+        uint8_t data_fault = 0;
+        _dev->read_registers(MAX31865_REG_FAULT_STATUS_READ, (uint8_t *)&data_fault, 1);
+        Debug("%d MAX31865 fault: 0x02X", _state.instance, data_fault);
+#endif
+        // clear the fault
+        _dev->write_register(MAX31865_REG_CONFIG_WRITE, MAX31865_CONFIG_VALUE);
+        return;
+    }
+
+    // For a temperature range of -100 C to +100 C, a good approximation of
+    // temperature can be made with simple linearization. This equation gives
+    // 0 C error at 0C, -1.75 C error at -100 C, and -1.4 C error at +100 C
+    const float temperature = ((float)data_temperature/32.0f) - 256.0f;
+
+#if MAX31865_DEBUGGING
+    Debug("%d MAX31865 %.2f C", _state.instance, temperature);
+#endif
+
+    set_temperature(temperature);
+}
+
+#endif // AP_TEMPERATURE_SENSOR_MAX31865_ENABLED
+

libraries/AP_TemperatureSensor/AP_TemperatureSensor_MAX31865.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2023 Kraus Hamdani Aerospace Inc. All rights reserved.
+ *
+ * This file 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 file 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/>.
+ *
+ * Code by Tom Pittenger
+ */
+/*
+    Implements SPI driver for MAX31865 digital RTD Temperature converter
+*/
+
+#pragma once
+#include "AP_TemperatureSensor_Backend.h"
+
+#if AP_TEMPERATURE_SENSOR_MAX31865_ENABLED
+
+class AP_TemperatureSensor_MAX31865 : public AP_TemperatureSensor_Backend {
+    using AP_TemperatureSensor_Backend::AP_TemperatureSensor_Backend;
+public:
+
+    void init(void) override;
+
+    void update(void) override {};
+
+private:
+    void thread_tick(void);
+};
+
+#endif // AP_TEMPERATURE_SENSOR_MAX31865_ENABLED

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
+    // @Values: 0:Disabled, 1:TSYS01, 2:MCP9600, 3:MAX31865
     // @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

@@ -30,6 +30,7 @@ public:
         NONE                        = 0,
         TSYS01                      = 1,
         MCP9600                     = 2,
+        MAX31865                    = 3,
     };
 
     // option to map to another system component

libraries/AP_TemperatureSensor/AP_TemperatureSensor_config.h

@@ -16,6 +16,10 @@
 #endif
 #endif
 
+#ifndef AP_TEMPERATURE_SENSOR_MAX31865_ENABLED
+    #define AP_TEMPERATURE_SENSOR_MAX31865_ENABLED AP_TEMPERATURE_SENSOR_ENABLED
+#endif
+
 
 
 // maximum number of Temperature Sensors