drivers: sensors: Implement MAX31865 sensor
This commit implements the temperature sensor interface for the Maxim MAX31865 SPI Temperature Sensor. Signed-off-by: Fin Maaß <fin.maass@haw-hamburg.de> Co-authored-by: Armin Brauns <armin.brauns@embedded-solutions.at>
This commit is contained in:
Fin Maaß
Anas Nashif
parent
5d240edc17
commit
cabc30c725
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@ -70,6 +70,7 @@ add_subdirectory_ifdef(CONFIG_MAX17055 max17055)
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add_subdirectory_ifdef(CONFIG_MAX17262 max17262)
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add_subdirectory_ifdef(CONFIG_MAX30101 max30101)
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add_subdirectory_ifdef(CONFIG_MAX31855 max31855)
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add_subdirectory_ifdef(CONFIG_MAX31865 max31865)
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add_subdirectory_ifdef(CONFIG_MAX31875 max31875)
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add_subdirectory_ifdef(CONFIG_MAX44009 max44009)
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add_subdirectory_ifdef(CONFIG_MAX6675 max6675)
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@ -181,6 +181,8 @@ source "drivers/sensor/max30101/Kconfig"
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source "drivers/sensor/max31855/Kconfig"
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source "drivers/sensor/max31865/Kconfig"
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source "drivers/sensor/max31875/Kconfig"
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source "drivers/sensor/max44009/Kconfig"
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5
drivers/sensor/max31865/CMakeLists.txt
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5
drivers/sensor/max31865/CMakeLists.txt
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@ -0,0 +1,5 @@
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# SPDX-License-Identifier: Apache-2.0
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zephyr_library()
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zephyr_library_sources(max31865.c)
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12
drivers/sensor/max31865/Kconfig
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12
drivers/sensor/max31865/Kconfig
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@ -0,0 +1,12 @@
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# MAX31865 temperature sensor configuration options
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# Copyright (c) 2022 HAW Hamburg FTZ-DIWIP
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# SPDX-License-Identifier: Apache-2.0
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config MAX31865
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bool "MAX31865 Temperature Sensor"
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default y
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depends on DT_HAS_MAXIM_MAX31865_ENABLED
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select SPI
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help
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Enable the driver for Maxim MAX31865 SPI Temperature Sensors.
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304
drivers/sensor/max31865/max31865.c
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304
drivers/sensor/max31865/max31865.c
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@ -0,0 +1,304 @@
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/*
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* Copyright (c) 2022 HAW Hamburg FTZ-DIWIP
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include "max31865.h"
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static int max31865_spi_write(const struct device *dev, uint8_t reg, uint8_t *data, size_t len)
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{
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const struct max31865_config *cfg = dev->config;
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const struct spi_buf bufs[] = {{
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.buf = ®,
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.len = 1,
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},
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{.buf = data, .len = len}};
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const struct spi_buf_set tx = {.buffers = bufs, .count = 2};
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return spi_write_dt(&cfg->spi, &tx);
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}
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static int max31865_spi_read(const struct device *dev, uint8_t reg, uint8_t *data, size_t len)
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{
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const struct max31865_config *cfg = dev->config;
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reg &= 0x7F;
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const struct spi_buf tx_buf = {.buf = ®, .len = 1};
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const struct spi_buf_set tx = {.buffers = &tx_buf, .count = 1};
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struct spi_buf rx_buf[] = {{
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.buf = ®,
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.len = 1,
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},
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{.buf = data, .len = len}};
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const struct spi_buf_set rx = {.buffers = rx_buf, .count = 2};
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return spi_transceive_dt(&cfg->spi, &tx, &rx);
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}
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/**
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* @brief Set device configuration register
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*
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* @param device device instance
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* @return 0 if successful, or negative error code from SPI API
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*/
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static int configure_device(const struct device *dev)
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{
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struct max31865_data *data = dev->data;
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uint8_t cmd[] = {data->config_control_bits};
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int err = max31865_spi_write(dev, WR(REG_CONFIG), cmd, 1);
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if (err < 0) {
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LOG_ERR("Error write SPI%d\n", err);
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}
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return err;
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}
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/**
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* @brief Set device fail threshold registers
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*
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* @param device device instance
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* @return 0 if successful, or negative error code from SPI API
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*/
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static int set_threshold_values(const struct device *dev)
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{
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const struct max31865_config *config = dev->config;
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uint8_t cmd[] = {
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(config->high_threshold >> 7) & 0x00ff, (config->high_threshold << 1) & 0x00ff,
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(config->low_threshold >> 7) & 0x00ff, (config->low_threshold << 1) & 0x00ff};
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int err = max31865_spi_write(dev, WR(REG_HIGH_FAULT_THR_MSB), cmd, 4);
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if (err < 0) {
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LOG_ERR("Error write SPI%d\n", err);
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}
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return err;
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}
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#ifdef CONFIG_NEWLIB_LIBC
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/**
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* Apply the Callendar-Van Dusen equation to convert the RTD resistance
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* to temperature:
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* Tr = (-A + SQRT(delta) ) / 2*B
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* delta = A^2 - 4B*(1-Rt/Ro)
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* For under zero, taken from
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* https://www.analog.com/media/en/technical-documentation/application-notes/AN709_0.pdf
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* @param resistance measured resistance
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* @param resistance_0 constant resistance at 0oC
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* @return calculated temperature
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*/
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static double calculate_temperature(double resistance, double resistance_0)
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{
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double temperature;
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double delta = (RTD_A * RTD_A) - 4 * RTD_B * (1.0 - resistance / resistance_0);
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temperature = (-RTD_A + sqrt(delta)) / (2 * RTD_B);
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if (temperature > 0.0) {
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return temperature;
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}
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resistance /= resistance_0;
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resistance *= 100.0;
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temperature = A[0] + A[1] * resistance + A[2] * pow(resistance, 2) +
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A[3] * pow(resistance, 3) + A[4] * pow(resistance, 4) +
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A[5] * pow(resistance, 5);
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return temperature;
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}
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#else
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/**
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* Apply a very good linear approximation of the Callendar-Van Dusen equation to convert the RTD
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* resistance to temperature:
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* @param resistance measured resistance
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* @param resistance_0 constant resistance at 0oC
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* @return calculated temperature
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*/
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static double calculate_temperature(double resistance, double resistance_0)
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{
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double temperature;
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temperature = (resistance - resistance_0) / (resistance_0 * RTD_A);
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return temperature;
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}
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#endif
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/**
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* @brief Enable/Disable Vbias for MAX31865
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*
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* @param device device instance
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* @param enable true, turn on vbias, false, turn off vbias
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* @return 0 if successful, or negative error code from SPI API
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*/
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static int max31865_set_vbias(const struct device *dev, bool enable)
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{
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struct max31865_data *data = dev->data;
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WRITE_BIT(data->config_control_bits, 7, enable);
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return configure_device(dev);
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}
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static char *max31865_error_to_string(uint8_t fault_register)
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{
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switch (fault_register) {
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case 0:
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return "No error";
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case MAX31865_FAULT_VOLTAGE:
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return "Over/under voltage fault";
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case MAX31865_FAULT_RTDIN_FORCE:
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return "RTDIN- < 0.85*VBIAS (FORCE- open)";
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case MAX31865_FAULT_REFIN_FORCE:
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return "REFIN- < 0.85*VBIAS (FORCE- open)";
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case MAX31865_FAULT_REFIN:
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return "REFIN- > 0.85*VBIAS";
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case MAX31865_FAULT_LOW_THRESHOLD:
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return "RTD below low threshold";
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case MAX31865_FAULT_HIGH_THRESHOLD:
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return "RTD above high threshold";
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}
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return "";
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}
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static int max31865_fault_register(const struct device *dev)
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{
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uint8_t fault_register;
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max31865_spi_read(dev, (REG_FAULT_STATUS), &fault_register, 1);
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struct max31865_data *data = dev->data;
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/*Clear fault register */
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WRITE_BIT(data->config_control_bits, 1, 1);
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configure_device(dev);
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LOG_ERR("Fault Register: 0x%02x, %s", fault_register,
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max31865_error_to_string(fault_register));
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WRITE_BIT(data->config_control_bits, 1, 0);
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return 0;
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}
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/**
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* @brief Get temperature value in oC for device
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*
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* @param device device instance
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* @param temperature measured temperature
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* @return 0 if successful, or negative error code
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*/
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static int max31865_get_temperature(const struct device *dev)
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{
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max31865_set_vbias(dev, true);
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union read_reg_u {
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uint8_t u8[2];
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uint16_t u16;
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} read_reg;
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read_reg.u16 = 0;
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/* Waiting Time for Temerature Conversion (Page 3 of the datasheet)*/
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k_sleep(K_MSEC(66));
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/* Read resistance measured value */
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int err = max31865_spi_read(dev, (REG_RTD_MSB), read_reg.u8, 2);
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max31865_set_vbias(dev, false);
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if (err < 0) {
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LOG_ERR("SPI read %d\n", err);
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return -EIO;
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}
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read_reg.u16 = sys_be16_to_cpu(read_reg.u16);
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LOG_DBG("RAW: %02X %02X , %04X", read_reg.u8[0], read_reg.u8[1], read_reg.u16);
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if (TESTBIT(read_reg.u16, 0)) {
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max31865_fault_register(dev);
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return -EIO;
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}
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const struct max31865_config *config = dev->config;
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struct max31865_data *data = dev->data;
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read_reg.u16 = read_reg.u16 >> 1;
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double resistance = (double)read_reg.u16;
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resistance /= 32768;
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resistance *= config->resistance_reference;
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data->temperature = calculate_temperature(resistance, config->resistance_at_zero);
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return 0;
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}
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static int max31865_init(const struct device *dev)
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{
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const struct max31865_config *config = dev->config;
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if (!spi_is_ready_dt(&config->spi)) {
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return -ENODEV;
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}
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struct max31865_data *data = dev->data;
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/* Set the confgiuration register */
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data->config_control_bits = 0;
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WRITE_BIT(data->config_control_bits, 6, config->conversion_mode);
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WRITE_BIT(data->config_control_bits, 5, config->one_shot);
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WRITE_BIT(data->config_control_bits, 4, config->three_wire);
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data->config_control_bits |= config->fault_cycle & 0b00001100;
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WRITE_BIT(data->config_control_bits, 0, config->filter_50hz);
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configure_device(dev);
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set_threshold_values(dev);
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max31865_set_vbias(dev, false);
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return 0;
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}
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static int max31865_sample_fetch(const struct device *dev, enum sensor_channel chan)
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{
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if (chan != SENSOR_CHAN_ALL && chan != SENSOR_CHAN_AMBIENT_TEMP) {
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LOG_ERR("Invalid channel provided");
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return -ENOTSUP;
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}
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return max31865_get_temperature(dev);
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}
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static int max31865_channel_get(const struct device *dev, enum sensor_channel chan,
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struct sensor_value *val)
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{
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struct max31865_data *data = dev->data;
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switch (chan) {
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case SENSOR_CHAN_AMBIENT_TEMP:
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return sensor_value_from_double(val, data->temperature);
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default:
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return -EINVAL;
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}
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}
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static const struct sensor_driver_api max31865_api_funcs = {
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.sample_fetch = max31865_sample_fetch,
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.channel_get = max31865_channel_get,
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};
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#define MAX31865_DEFINE(inst) \
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\
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static struct max31865_data max31865_data_##inst; \
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\
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static const struct max31865_config max31865_config_##inst = { \
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.spi = SPI_DT_SPEC_INST_GET(inst, SPI_MODE_CPHA | SPI_WORD_SET(8), 0), \
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.resistance_at_zero = DT_INST_PROP(inst, resistance_at_zero), \
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.resistance_reference = DT_INST_PROP(inst, resistance_reference), \
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.conversion_mode = false, \
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.one_shot = true, \
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.three_wire = DT_INST_PROP(inst, maxim_3_wire), \
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.fault_cycle = MAX31865_FAULT_DETECTION_NONE, \
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.filter_50hz = DT_INST_PROP(inst, filter_50hz), \
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.low_threshold = DT_INST_PROP(inst, low_threshold), \
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.high_threshold = DT_INST_PROP(inst, high_threshold), \
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}; \
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\
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SENSOR_DEVICE_DT_INST_DEFINE(inst, max31865_init, NULL, &max31865_data_##inst, \
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&max31865_config_##inst, POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY, \
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&max31865_api_funcs);
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/* Create the struct device for every status "okay" node in the devicetree. */
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DT_INST_FOREACH_STATUS_OKAY(MAX31865_DEFINE)
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96
drivers/sensor/max31865/max31865.h
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96
drivers/sensor/max31865/max31865.h
Normal file
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@ -0,0 +1,96 @@
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/*
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* Copyright (c) 2022 HAW Hamburg FTZ-DIWIP
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef _MAX31865_H
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#define _MAX31865_H
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#define DT_DRV_COMPAT maxim_max31865
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#include <math.h>
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#include <zephyr/drivers/sensor.h>
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#include <zephyr/drivers/spi.h>
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#include <zephyr/kernel.h>
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#include <zephyr/logging/log.h>
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#include <zephyr/sys/util_macro.h>
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#include <zephyr/sys/byteorder.h>
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LOG_MODULE_REGISTER(MAX31865, CONFIG_SENSOR_LOG_LEVEL);
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#define MAX31865_FAULT_HIGH_THRESHOLD BIT(7)
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#define MAX31865_FAULT_LOW_THRESHOLD BIT(6)
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#define MAX31865_FAULT_REFIN BIT(5)
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#define MAX31865_FAULT_REFIN_FORCE BIT(4)
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#define MAX31865_FAULT_RTDIN_FORCE BIT(3)
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#define MAX31865_FAULT_VOLTAGE BIT(2)
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#define MAX31865_FAULT_DETECTION_NONE (0x00 << 2)
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#define MAX31865_FAULT_DETECTION_AUTO (0x01 << 2)
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#define MAX31865_FAULT_DETECTION_MANUAL_1 (0x02 << 2)
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#define MAX31865_FAULT_DETECTION_MANUAL_2 (0x03 << 2)
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/* Read Register Address */
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#define REG_CONFIG 0x00
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#define REG_RTD_MSB 0x01
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#define REG_RTD_LSB 0x02
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#define REG_HIGH_FAULT_THR_MSB 0x03
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#define REG_HIGH_FAULT_THR_LSB 0x04
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#define REG_LOW_FAULT_THR_MSB 0x05
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#define REG_LOW_FAULT_THR_LSB 0x06
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#define REG_FAULT_STATUS 0x07
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#define WR(reg) ((reg) | 0x80)
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/**
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* RTD data, RTD current, and measurement reference
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* voltage. The ITS-90 standard is used; other RTDs
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* may have coefficients defined by the DIN 43760 or
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* the U.S. Industrial (American) standard.
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*/
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#define RTD_A_ITS90 3.9080e-3
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#define RTD_A_USINDUSTRIAL 3.9692e-3
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#define RTD_A_DIN43760 3.9848e-3
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#define RTD_B_ITS90 -5.870e-7
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#define RTD_B_USINDUSTRIAL -5.8495e-7
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#define RTD_B_DIN43760 -5.8019e-7
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/**
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* RTD coefficient C is required only for temperatures
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* below 0 deg. C. The selected RTD coefficient set
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* is specified below.
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*/
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#define RTD_A (RTD_A_ITS90)
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#define RTD_B (RTD_B_ITS90)
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/*
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* For under zero, taken from
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* https://www.analog.com/media/en/technical-documentation/application-notes/AN709_0.pdf
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*/
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static const float A[6] = {-242.02, 2.2228, 2.5859e-3, 4.8260e-6, 2.8183e-8, 1.5243e-10};
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struct max31865_data {
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double temperature;
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uint8_t config_control_bits;
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};
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/**
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* Configuration struct to the MAX31865.
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*/
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struct max31865_config {
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const struct spi_dt_spec spi;
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uint16_t resistance_at_zero;
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uint16_t resistance_reference;
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bool conversion_mode;
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bool one_shot;
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bool three_wire;
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uint8_t fault_cycle;
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bool filter_50hz;
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uint16_t low_threshold;
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uint16_t high_threshold;
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};
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/* Bit manipulation macros */
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#define TESTBIT(data, pos) ((0u == (data & BIT(pos))) ? 0u : 1u)
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#endif
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44
dts/bindings/sensor/maxim,max31865.yaml
Normal file
44
dts/bindings/sensor/maxim,max31865.yaml
Normal file
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@ -0,0 +1,44 @@
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# Copyright (c) 2022, HAW Hamburg FTZ-DIWIP
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# SPDX-License-Identifier: Apache-2.0
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description: |
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||||
Maxim MAX31865 SPI RTD-to-Digital Converter Temperature Sensor.
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Find the datasheet here:
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||||
https://datasheets.maximintegrated.com/en/ds/MAX31865.pdf
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||||
|
||||
compatible: "maxim,max31865"
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||||
|
||||
include: [sensor-device.yaml, spi-device.yaml]
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||||
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||||
properties:
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resistance-at-zero:
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||||
type: int
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||||
required: true
|
||||
description: Sensor resistance in ohms at 0 Celsius (100 ohms for PT100, 1000 ohms for PT1000)
|
||||
|
||||
resistance-reference:
|
||||
type: int
|
||||
required: true
|
||||
description: Circuit reference resistance in ohms (recommended on MAX31865 datasheet 400 ohms
|
||||
for PT100, 4000 ohms for PT1000, the Adafruit boards use 430 ohms and 4300 ohms)
|
||||
|
||||
low-threshold:
|
||||
type: int
|
||||
default: 0
|
||||
description: Low fault threshold (ADC CODE, 15-bit value, unit-free, default value is the
|
||||
minimum value)
|
||||
|
||||
high-threshold:
|
||||
type: int
|
||||
default: 32767
|
||||
description: High fault threshold (ADC CODE, 15-bit value, unit-free, default value is the
|
||||
maximum value)
|
||||
|
||||
maxim,3-wire:
|
||||
type: boolean
|
||||
description: 3-wire enabled (@a true) or 2-wire/4-wire (@a false)
|
||||
|
||||
filter-50hz:
|
||||
type: boolean
|
||||
description: 50 Hz filter enabled (@a true) or 60 Hz filter enabled (@a false)
|
||||
|
|
@ -343,3 +343,14 @@ test_spi_max31855: max31855@29 {
|
|||
reg = <0x29>;
|
||||
spi-max-frequency = <0>;
|
||||
};
|
||||
|
||||
test_spi_max31865: max31865@2a {
|
||||
compatible = "maxim,max31865";
|
||||
reg = <0x2a>;
|
||||
spi-max-frequency = <125000>;
|
||||
resistance-at-zero = <100>;
|
||||
resistance-reference = <430>;
|
||||
low-threshold = <6579>;
|
||||
high-threshold = <32767>;
|
||||
filter-50hz;
|
||||
};
|
||||
|
|
|
|||
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Reference in a new issue