.. _softdevice_controller_limitations:

Limitations
###########

When working with the SoftDevice Controller, you should be aware of the following limitations.
In addition, see :ref:`nrf:known_issues` for temporary issues that will be fixed in future releases.

YOPAN-87: The RSSI value reported by the SoftDevice Controller requires additional temperature compensation
  The RSSI value reported by the SoftDevice Controller is the raw value from the radio peripheral.
  Some SoCs require compensation of the RSSI value based on the chip temperature.
  See the Errata document for the respective SoC for detailed information.

  **Workaround:**
  For the nRF53 Series, you can retrieve the chip temperature by reading the value of the temperature peripheral on the network core.
  To do this with the SoftDevice Controller, use the Zephyr HCI VS Read Chip Temperature command (``BT_HCI_OP_VS_READ_CHIP_TEMP``).

  For the nRF52 Series, you can use the Zephyr sensor API instead of the HCI command to retrieve the chip temperature.

  You can then use the retrieved temperature value to compensate the raw RSSI value, following the workaround in the Errata document.

DRGN-8628: Setting Filter_Duplicates in LE Set Scan Enable and LE Set Extended Scan Enable commands does not take effect
  The host receives all advertisements from advertisers in advertising report events even if Filter_Duplicates is set in LE Set Scan Enable and LE Set Extended Scan Enable.
  Filter_Duplicates cannot guarantee that all duplicate advertising reports are filtered out, because the controller has a limited "cache" of known advertising reports.

  **Workaround:** Filter out the duplicate advertising reports in the application.

DRGN-8476: Long packets not supported in connections on Coded PHY
  In connections, the Link Layer payload size is limited to 27 bytes on LE Coded PHY.

DRGN-9083: AAR populated with zero IRK
  If the application has set an all zeroes IRK for a device in the resolving list, then a resolvable address that can be resolved with the all zeroes IRK will be reported to the application as that device in the advertisement report or the connected event.

DRGN-11297: Maximum connection interval of 10 ms before entering LLPM-mode
  The maximum connection interval that can be active when switching to a connection interval of 1 ms is 10 ms.

  **Workaround:** An application that needs to use a higher interval than 10 ms must perform two connection updates to use 1 ms connection interval:

  * A first update to 10 ms connection interval.
  * A second update to 1 ms connection interval.

DRGN-8569: SEVONPEND flag must not be modified
  Applications must not modify the SEVONPEND flag in the SCR register when running in priority levels higher than 6 (priority level numerical values lower than 6), as this can lead to undefined behavior.

DRGN-6362: Synthesized low frequency clock source not tested
  Synthesized low frequency clock source is not tested or intended for use with the SoftDevice Controller.

DRGN-12259: HCI Receiver and Transmitter Test commands not available
  The HCI Receiver and Transmitter Test commands are not available.

  **Workaround:** To perform a radio test, use the :ref:`direct_test_mode` sample.
  For nRF52 Series devices, you can choose to use the DTM application in the nRF5 SDK instead.

DRGN-15989: In some cases, the SDC can connect to the peer it is already connected to
  To prevent this, the application can remove the already connected peer from the Filter Accept List, or from the Resolving List, or not use that peer's address in Create Connection command.

DRGN-17724: The AoA transmitter is not supported in LLPM-mode
  The AoA transmitter can show unspecified behavior when being used in LLPM-mode.

DRGN-20336: Sending and receiving ISO SDUs larger than 247 bytes is not supported.

DRGN-21099: Unsupported CIG parameters when requesting framed PDUs
  The following parameters to the LE Set CIG Parameters command are not supported when framed PDUs are requested:

  * Unequal ``SDU_Interval_C_To_P`` and ``SDU_Interval_P_To_C``.
    This applies only when the data transfer is bidirectional.
  * An ``SDU_Interval`` lower than 5000 µs.
  * A ``Max_SDU`` larger than 246 bytes.

  Note that framed PDUs will be enforced if neither of the following conditions are met:

  * ``SDU_Interval`` is an integer multiple of 1250 µs.
  * ``SDU_Interval`` is an integer divisor of 5000 µs.

  In this case, the unsupported parameters mentioned above still apply.

  **Workaround:** Use the LE Set CIG Parameters Test command.

DRGN-21246: Unsupported BIG parameters
  The following parameters are not supported when the HCI LE Create BIG command is used:

  * An ``SDU_Interval`` shorter than 1250 µs.
  * A ``Max_SDU`` larger than 247 bytes.
  * An ``SDU_Interval`` shorter than 5000 µs when using framed PDUs.
  * A ``Max_SDU`` larger than 246 bytes when using framed PDUs.

  Note that framed PDUs will be enforced if ``SDU_Interval`` is not an integer multiple of 1250 µs.