60 lines
2.7 KiB
ReStructuredText
60 lines
2.7 KiB
ReStructuredText
RF calibration
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==============
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ESP32 supports three RF calibration methods during RF initialization:
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1. Partial calibration
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2. Full calibration
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3. No calibration
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Partial calibration
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-------------------
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During RF initialization, the partial calibration method is used by default for RF calibration.
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It is done based on the full calibration data which is stored in the NVS.
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To use this method, please go to ``menuconfig`` and enable :ref:`CONFIG_ESP32_PHY_CALIBRATION_AND_DATA_STORAGE`.
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Full calibration
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----------------
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Full calibration is triggered in the follwing conditions:
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1. NVS does not exist.
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2. The NVS partition to store calibration data is erased.
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3. Hardware MAC address is changed.
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4. PHY library version is changed.
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5. The RF calibration data loaded from the NVS partition is broken.
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It takes about 100ms more than partial calibration.
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If boot duration is not critical, it is suggested to use the full calibration method.
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To switch to the full calibration method, go to ``menuconfig`` and disable :ref:`CONFIG_ESP32_PHY_CALIBRATION_AND_DATA_STORAGE`.
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If you use the default method of RF calibration, there are two ways to add the function of triggering full calibration as a last-resort remedy.
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1. Erase the NVS partition if you don't mind all of the data stored in the NVS partition is erased. That is indeed the easiest way.
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2. Call API :cpp:func:`esp_phy_erase_cal_data_in_nvs` before initializing WiFi and BT/BLE based on some conditions (e.g. an option provided in some diagnostic mode).
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In this case, only phy namespace of the NVS partition is erased.
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No calibration
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---------------
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No calibration method is only used when ESP32 wakes up from deep sleep.
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PHY initialization data
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-----------------------
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The PHY initialization data is used for RF calibration.
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There are two ways to get the PHY initialization data.
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One is the default initialization data which is located in the header file :idf_file:`components/esp32/phy_init_data.h`.
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It is embedded into the application binary after compiling and then stored into read-only memory (DROM).
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To use the default initialization data, please go to ``menuconfig`` and disable :ref:`CONFIG_ESP32_PHY_INIT_DATA_IN_PARTITION`.
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Another is the initialization data which is stored in a partition.
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When using a custom partition table, make sure that PHY data partition is included (type: `data`, subtype: `phy`).
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With default partition table, this is done automatically.
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If initialization data is stored in a partition, it has to be flashed there, otherwise runtime error will occur.
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To switch to the initialization data stored in a partition, go to ``menuconfig`` and enable :ref:`CONFIG_ESP32_PHY_INIT_DATA_IN_PARTITION`.
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