esp_read_mac derives wrong MAC address for Bluetooth in some configurations (IDFGH-3343)

[devanlai]

Environment

• Development Kit: ESP32-DevKitC
• Kit version (for WroverKit/PicoKit/DevKitC): v4
• Module or chip used: ESP32-WROOM-32
• IDF version: v4.2-dev-1575-ga3520970f
• Build System: idf.py
• Compiler version: xtensa-esp32-elf-gcc (crosstool-NG esp-2020r1) 8.2.0
• Operating System: Linux
• Using an IDE?: No
• Power Supply: USB

Problem Description

When the number of universally administered MAC addresses is set to two, the derived Bluetooth MAC address does not match the API documentation.

Per the documentation, the derived BT MAC address when the number of universal MAC addresses is set to two should be formed by adding one to the last octet. However, instead, the BT MAC address is formed by adding two to the last octet.

In the test program below with CONFIG_ESP32_UNIVERSAL_MAC_ADDRESSES=2, the base MAC address is set to 00:01:02:03:04:00.

Expected Behavior

The bluetooth MAC address should be set to 00:01:02:03:04:01

Actual Behavior

The bluetooth MAC address is set to 00:01:02:03:04:02

I (325) BASE MAC    : 00:01:02:03:04:00
I (325) WIFI_STA MAC: 00:01:02:03:04:00
I (335) SoftAP MAC  : 02:01:02:03:04:00
I (335) BT MAC      : 00:01:02:03:04:02
I (345) Ethernet MAC: 02:01:02:03:04:01

For reference, here is the output when the number of universal MAC addresses is set to 4, which is correct:

I (324) BASE MAC    : 00:01:02:03:04:00
I (324) WIFI_STA MAC: 00:01:02:03:04:00
I (334) SoftAP MAC  : 00:01:02:03:04:01
I (334) BT MAC      : 00:01:02:03:04:02
I (344) Ethernet MAC: 00:01:02:03:04:03

Code to reproduce this issue

Sample gist based on the base_mac_address example:
https://gist.github.com/devanlai/8d2ce9aacd197ebc3214027a7ffd042b

[ghost]

Hi, @devanlai

Please apply this patch bt_mac.zip
.

Thanks
Weitianhua

[devanlai]

Hi @Wth-Esp, I can confirm that this patch fixes the issue for me. Looking forward to seeing the patch land in the public repo.

[ghost]

Hi @devanlai

There is already an MR to fix this issue, and will soon sync on Github.
Thanks for your support.

Thanks
Weitianhua