External Thermistor#

RAIL_StartThermistorMeasurement#

RAIL_Status_t RAIL_StartThermistorMeasurement (RAIL_Handle_t railHandle)

Start a thermistor measurement.

Returns

• Status code indicating success of the function call. Returns RAIL_STATUS_INVALID_STATE if the thermistor is started while the radio is transmitting.

To get the thermistor impedance, call the function RAIL_GetThermistorImpedance(). On platforms having RAIL_SUPPORTS_EXTERNAL_THERMISTOR, this function reconfigures GPIO_THMSW_EN_PIN located in GPIO_THMSW_EN_PORT. To locate this pin, refer to the data sheet or appropriate header files of the device. For proper operation, RAIL_Init() must be called before using this function.

Note

• When an EFF is attached, this function must not be called during transmit.

Warnings

• This API is not safe to use in a multiprotocol app.

• As this function relies on EMU, GPIO and HFXO access and RAIL is meant to run in TrustZone non-secure world, it is not supported if EMU, GPIO or HFXO are configured as secure peripheral and it will return RAIL_STATUS_INVALID_CALL.

RAIL_GetThermistorImpedance#

RAIL_Status_t RAIL_GetThermistorImpedance (RAIL_Handle_t railHandle, uint32_t * thermistorImpedance)

Get the thermistor impedance measurement and return RAIL_INVALID_THERMISTOR_VALUE if the thermistor is not properly configured or the thermistor measurement is not ready.

Returns

• Status code indicating success of the function call.

Note

• This function is already called in RAIL_CalibrateHFXO(). It does not need to be manually called during the compensation sequence.

RAIL_ConvertThermistorImpedance#

RAIL_Status_t RAIL_ConvertThermistorImpedance (RAIL_Handle_t railHandle, uint32_t thermistorImpedance, int16_t * thermistorTemperatureC)

Convert the thermistor impedance into temperature, in Celsius.

Returns

• Status code indicating success of the function call.

A version of this function is provided in the Thermistor Utility plugin for Silicon Labs radio boards. For custom boards this function can be modified and re-implemented as needed.

Note

• This plugin is mandatory on EFR32xG25 platform.

RAIL_ComputeHFXOPPMError#

RAIL_Status_t RAIL_ComputeHFXOPPMError (RAIL_Handle_t railHandle, int16_t crystalTemperatureC, int8_t * crystalPPMError)

Compute the crystal PPM deviation from the thermistor temperature.

Returns

• Status code indicating success of the function call.

This function is provided in the rail_util_thermistor plugin to get accurate values from our boards thermistor. For a custom board, this function could be modified and re-implemented for other needs.

Note

• This plugin is mandatory on EFR32xG25 platform.

RAIL_ConfigHFXOThermistor#

RAIL_Status_t RAIL_ConfigHFXOThermistor (RAIL_Handle_t railHandle, const RAIL_HFXOThermistorConfig_t * pHfxoThermistorConfig)

Configure the GPIO for thermistor usage.

Returns

• Status code indicating the result of the function call.

Note

• The port and pin that must be passed in RAIL_HFXOThermistorConfig_t are GPIO_THMSW_EN_PORT and GPIO_THMSW_EN_PIN respectively.

Warnings

• As this function relies on GPIO access and RAIL is meant to run in TrustZone non-secure world, it is not supported if GPIO is configured as secure peripheral and it will return RAIL_STATUS_INVALID_CALL.

RAIL_ConfigHFXOCompensation#

RAIL_Status_t RAIL_ConfigHFXOCompensation (RAIL_Handle_t railHandle, const RAIL_HFXOCompensationConfig_t * pHfxoCompensationConfig)

Configure the temperature parameters for HFXO compensation.

Returns

• Status code indicating the result of the function call.

Note

• This function must be called after RAIL_ConfigHFXOThermistor() to succeed.

In RAIL_HFXOCompensationConfig_t, deltaNominal and deltaCritical define the temperature variation triggering a new compensation. The field zoneTemperatureC defines the temperature separating the nominal case (below) from the critical one (above).

When enabled and either deltaNominal or deltaCritical are exceeded, RAIL raises event RAIL_EVENT_CAL_NEEDED with RAIL_CAL_TEMP_HFXO bit set. The API RAIL_StartThermistorMeasurement() must be called afterwards. The latter will raise RAIL_EVENT_THERMISTOR_DONE with calibration bit RAIL_CAL_COMPENSATE_HFXO set and a call to RAIL_CalibrateHFXO() must follow.

Note

• Set deltaNominal and deltaCritical to 0 to perform compensation after each transmit.

RAIL_GetHFXOCompensationConfig#

RAIL_Status_t RAIL_GetHFXOCompensationConfig (RAIL_Handle_t railHandle, RAIL_HFXOCompensationConfig_t * pHfxoCompensationConfig)

Get the temperature parameters for HFXO compensation.

Returns

• Status code indicating the result of the function call.

RAIL_CompensateHFXO#

RAIL_Status_t RAIL_CompensateHFXO (RAIL_Handle_t railHandle, int8_t crystalPPMError)

Compute a frequency offset and compensate HFXO accordingly.

Returns

• Status code indicating success of the function call.

Note

• This function only works for platforms having RAIL_SUPPORTS_EXTERNAL_THERMISTOR alongside RAIL_SUPPORTS_HFXO_COMPENSATION.

RAIL_INVALID_THERMISTOR_VALUE#

#define RAIL_INVALID_THERMISTOR_VALUE

(0xFFFFFFFFU)

A sentinel value to indicate an invalid thermistor measurement value.

RAIL_INVALID_PPM_VALUE#

#define RAIL_INVALID_PPM_VALUE

(-128)

A sentinel value to indicate an invalid PPM calculation value.