max31865 - Driver for MAX31865 resistance converter for platinum RTDs¶

group max31865

ESP-IDF driver for MAX31865, resistance converter for platinum RTDs.

BSD Licensed as described in the file LICENSE

Defines

MAX31865_MAX_CLOCK_SPEED_HZ¶

Enums

enum max31865_mode_t¶

Conversion mode.

Values:

enumerator MAX31865_MODE_SINGLE¶: Single consersion mode, default.

enumerator MAX31865_MODE_AUTO¶: Automatic conversion mode at 50/60Hz rate.

enum max31865_filter_t¶

Notch frequencies for the noise rejection filter.

Values:

enumerator MAX31865_FILTER_60HZ¶: 60Hz

enumerator MAX31865_FILTER_50HZ¶: 50Hz

enum max31865_connection_type_t¶

Connection type.

Values:

enumerator MAX31865_2WIRE¶: 2 wires

enumerator MAX31865_3WIRE¶: 3 wires

enumerator MAX31865_4WIRE¶: 4 wires

enum max31865_standard_t¶

Temperature scale standard.

Values:

enumerator MAX31865_ITS90¶: ITS-90.

enumerator MAX31865_DIN43760¶: DIN43760.

enumerator MAX31865_US_INDUSTRIAL¶: US INDUSTRIAL.

Functions

esp_err_t max31865_init_desc(max31865_t *dev, spi_host_device_t host, uint32_t clock_speed_hz, gpio_num_t cs_pin)¶

Initialize device descriptor.

Parameters

dev – Device descriptor
host – SPI host
clock_speed_hz – SPI clock speed, Hz
cs_pin – CS GPIO number

Returns

ESP_OK on success

esp_err_t max31865_free_desc(max31865_t *dev)¶

Free device descriptor.

Parameters: dev – Device descriptor
Returns: ESP_OK on success

esp_err_t max31865_set_config(max31865_t *dev, const max31865_config_t *config)¶

Configure device.

Parameters

dev – Device descriptor
config – Configuration

Returns

ESP_OK on success

esp_err_t max31865_get_config(max31865_t *dev, max31865_config_t *config)¶

Read device configuration.

Parameters

dev – Device descriptor
config – [out] Configuration

Returns

ESP_OK on success

esp_err_t max31865_start_measurement(max31865_t *dev)¶

Trigger single-shot measurement.

Parameters: dev – Device descriptor
Returns: ESP_OK on success

esp_err_t max31865_read_raw(max31865_t *dev, uint16_t *raw, bool *fault)¶

Read raw RTD value.

Parameters

dev – Device descritptor
raw – [out] Raw 15 bits RTD value
fault – [out] true when fault is detected

Returns

ESP_OK on success

esp_err_t max31865_read_temperature(max31865_t *dev, float *temp)¶

Read RTD value and convert it temperature.

Parameters

dev – Device descritptor
temp – [out] Temperature, deg. Celsius

Returns

ESP_OK on success

esp_err_t max31865_measure(max31865_t *dev, float *temp)¶

Measure temperature.

Run full cycle of single-shot measurement:

trigger measurement
wait for 70ms
read and convert RTD value

Parameters

dev – Device descritptor
temp – [out] Temperature, deg. Celsius

Returns

ESP_OK on success

esp_err_t max31865_detect_fault_auto(max31865_t *dev)¶

Run automatical fault detection cycle.

After calling this function, device must be reconfigured

Parameters: dev – Device descriptor
Returns: ESP_OK on success

esp_err_t max31865_get_fault_status(max31865_t *dev, uint8_t *fault_status)¶

Get bits of current fault status.

See datasheet for fault status interpretation

Parameters

dev – Device descriptor
fault_status – [out] Fault status bits

Returns

ESP_OK on success

esp_err_t max31865_clear_fault_status(max31865_t *dev)¶

Clear current fault status.

After calling this function, device must be reconfigured

Parameters: dev – Device descriptor
Returns: ESP_OK on success

struct max31865_config_t¶: #include <max31865.h>

Device configuration.

struct max31865_t¶

#include <max31865.h>

Device descriptor.

Public Members

spi_device_interface_config_t spi_cfg¶: SPI device configuration.

spi_device_handle_t spi_dev¶: SPI device handler.

max31865_standard_t standard¶: Temperature scale standard.

float r_ref¶: Reference resistor value, Ohms.

float rtd_nominal¶

RTD nominal resistance at 0 deg.

C, Ohms (PT100 - 100 Ohms, PT1000 - 1000 Ohms)