esp32c3 calibration seems not working when BLE only with ESP-IDF after 5.1.4 (IDFGH-14765)

[yuki-sato]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

IDF version.

v5.1.6

Espressif SoC revision.

esp32-c3

Operating System used.

macOS

How did you build your project?

Command line with CMake

If you are using Windows, please specify command line type.

None

Development Kit.

my own

Power Supply used.

External 3.3V

What is the expected behavior?

We use HCI command to control BLE and collect iBeacons.
We found that 10% of our esp32-c3 report low-level rssi.
It should be around 45 but it reports around 80.
Downgrading ESP-IDF solve this problem

What is the actual behavior?

It reports low-level RSSI of ble packet and missing rate is bad.

If you turn Wi-Fi ON, then BLE RSSI seems good range(45-55).
I suspect Calibration is not working under BLE only situation with ESP-IDF 5.1.4 and later.

Steps to reproduce.

1. Build with ESP-IDF v5.1.4( or 5.1.6 )
2. Run Only BLE
3. Collect RSSI data. it seems low.
4. Turn on Wi-Fi and BLE
5. Then you can see correct RSSI levels.

This occurs not every esp32-c3. We found it around 10% of esp32-c3.

Debug Logs.

iBeacon logs. last one is RSSI of iBeacon ESP32 got.

Only BLE

2025-03-03 16:37:19.170, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -72
2025-03-03 16:37:19.290, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -72
2025-03-03 16:37:19.290, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -72
2025-03-03 16:37:19.290, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -50
2025-03-03 16:37:19.291, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -50
2025-03-03 16:37:19.529, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -71
2025-03-03 16:37:19.529, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -71
2025-03-03 16:37:19.600, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -46
2025-03-03 16:37:19.600, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -50
2025-03-03 16:37:19.769, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -72
2025-03-03 16:37:19.770, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -72
2025-03-03 16:37:19.830, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -50
2025-03-03 16:37:19.830, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -50


BLE+Wi-Fi (same device)

2025-03-03 16:38:18.369, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -49
2025-03-03 16:38:19.497, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -42
2025-03-03 16:38:19.627, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -35
2025-03-03 16:38:19.627, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -42
2025-03-03 16:38:19.939, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -43
2025-03-03 16:38:19.939, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -43
2025-03-03 16:38:20.007, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -45
2025-03-03 16:38:20.008, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -71
2025-03-03 16:38:20.418, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -50
2025-03-03 16:38:20.419, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -50
2025-03-03 16:38:20.556, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -38
2025-03-03 16:38:20.557, 9f8a7ae3-5d01-49e4-9329-312032d434e2, 1, 100, -43

More Information.

We tries changing calibration procedure like changing CONFIG_ESP_PHY_CALIBRATION_AND_DATA_STORAGE on/off and calling esp_phy_erase_cal_data_in_nvs() before starting BLE. But these never helped.

Only "Turning On Wi-Fi" or "Downgrading ESP-IDF" works.