1/3 Bug Advisory Title Bug Advisory Concerning Low Wi-Fi Transmit Power on ESP32-C3 (chip revision v0.1 ~ v1.0) Issue Date 2024/07/09 Advisory Number AR2024-002 Serial Number NA Version v1.0 Issue Summary For ESP32-C3 chips (chip revision v0.1 ~ v1.0), using specific PHY versions and configurations can result in a 20 dB decrease in Wi-Fi transmit power in certain ESP-IDF versions. Preconditions for Issue The occurrence of this issue requires the simultaneous fulfillment of the following three conditions: 1. The ESP32-C3 chip revision is v0.1 ~ v1.0 (chips with revision v1.1 and above are not affected). 2. Using affected ESP-IDF versions or PHY version v1000 ~ v1130. Note: Follow these steps to check the PHY version used: 1）Build the station example located at $IDF_PATH/examples/wifi/getting_started/station. 2) Flash the station bin file to the development board. 3) Check the PHY version on the phy_init line in the boot log. For example, by following the above steps, you can obtain a log like the one shown below. In the figure, the PHY version is v1150. 2/3 3. One of the following three scenarios is satisfied: a) The Menuconfig option CONFIG_ESP_PHY_INIT_DATA_IN_PARTITION has been disabled, phy_init_data.c / phy_init_data.h has been modified, and phy_init_data[18] has been set to 1. b) The Menuconfig option CONFIG_ESP_PHY_INIT_DATA_IN_PARTITION has been enabled, phy_init_data.bin has been modified, and the 26th bit of [0:127] has been set to 1. c) The Menuconfig option CONFIG_ESP_PHY_INIT_DATA_IN_PARTITION has been enabled, and the option CONFIG_ESP_PHY_MULTIPLE_INIT_DATA_BIN has been enabled. ESP-IDF Affected Versions: ESP-IDF Branch Affected Commit IDs Affected ESP-IDF Versions master 0672067e - 946fdfce (excluded) NA release/v5.2 0672067e - 8ab1027f (excluded) v5.2-beta1 ~ v5.2 release/v5.1 9331e240 - 7cbee80f (excluded) v5.1.2 release/v5.0 cf4c628e - 090dd404 (excluded) v5.0.4 ~ v5.0.5 release/v4.4 e2782777 - fe0da0ee (excluded) v4.4.6 release/v4.3 bb95e4ca - 2463efbc (excluded) v4.3.6 ~ v4.3.7 ESP-IDF Patched Versions: ESP-IDF Branch Fixed Commit ID Fixed ESP-IDF Version master 946fdfce NA release/v5.2 8ab1027f Fixed in v5.2.1 release/v5.1 7cbee80f Fixed in v5.1.3 release/v5.0 090dd404 Fixed in v5.0.6 release/v4.4 fe0da0ee Fixed in v4.4.7 release/v4.3 2463efbc Fixed in a commit of release/v4.3 Note: ESP-IDF v4.3 & ESP-IDF v4.4 has officially reached the end of maintenance. Espressif will no longer provide support for adding new features, fixing bugs, or addressing security issues in this version. However, a fix commit has been submitted based on v4.3.7 due to the high impact of this issue. 3/3 Recommendations for Application Developers If you encounter this issue in your application, it is recommended to the fixed ESP- IDF versions (see the table above). If you encounter any problems during the upgrade process, please provide the ESP-IDF version or Commit ID to Espressif. We will assist you in resolving the related issues as soon as possible.