The Espressif Wi-Fi solution supports automatic RF calibration mechanism. The auto-calibration function is realized in conjunction with the external hardware components on the Wi-Fi module such as the antenna.

To enhance the reliability of RF performance, a sector containing RF calibration parameters has been added to the SDK since the release of version 1.5.4.1. SDK versions earlier than V1.5.4.1 have the limitation of flash map.  It is not clear that which sector of flash is available in users’ systems. Therefore the older SDK versions need to be upgraded. Function “user_rf_cal_sector_set” in the SDK needs to be called to specify the “rf_sector”. Please refer to “2C-ESP8266__SDK_API_Guide” (download here) for more details. In addition, “esp_init_data_default.bin” has been modified in this release.

At the first boot up of SDK, the chip internally performs automatic RF calibration according to the conditions of the peripheral components such as the antenna. The RF calibration parameters will be retained in the predetermined sector. A lack of SDK upgrade would decrease the reliability of RF performance. Espressif strongly recommends that users upgrade the SDK to the latest version and install all the patches. The upgrade will not affect any features developed based on the original SDK.

Please feel free to email feedback@espressif.com for technical inquiries.

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