ESP32 same MAC Address for 500 units

[nucleon]

Hello,

We purchased 400-500 units of (ESP32-WROOM-32D) from the parts distributor Mouser and when reading the efuse containing the MAC it seems that they are all the same. Is this a normal case scenario or should it these fuses be burned unique?

Thank you,

nucleon

[ESP_Angus]

Hi nucleon,

Thanks for letting us know about this. The MAC addresses should be unique.

Could you give an example of how you're reading the MAC and what the value you read is, please?

Angus

[nucleon]

Hello,

I am using <soc/efuse_reg.h>

Code: Select all

uint32_t mac = REG_GET_FIELD(EFUSE_BLK0_RDATA2_REG, EFUSE_RD_WIFI_MAC_CRC_HIGH);

printf("0x%X", mac);

0xBF8CAA

Thank you,

nucleon

[ESP_Angus]

Hi nucleon,

The high bytes (first bytes) of the 6 byte MAC will be the same for devices from the same batch. They will likely all share the same OUI (organizational identifier) at minimum. I think in the case of the MAC you have the OUI will be 8C-AA-B5 (the B5 is one of the lower 4 bytes so not shown in your output, the other byte in your output is the MAC CRC).

If you also read the lower 4 bytes of the MAC (register EFUSE_BLK0_RDATA1_REG, field EFUSE_RD_WIFI_MAC_CRC_LOW) then you should find the total address is unique.

ESP-IDF also has an API to read the MAC as a byte array, esp_read_mac(). (Each interface in the ESP32 has a unique sequential MAC and the eFuse holds the base MAC, the exact algorithm is described here).

esptool also prints the MAC when it connects to the device to flash it or for another purpose, so you can cross-reference this value for an easy check of the MAC.

[nucleon]

Thank you

[myflightdeck]

I was hoping someone might clarify this a little more.

I am trying to use the mac address as a unique identifier, but I keep running into an issue where the mac address appears the same from multiple ESP32 chips. From the response above to this question, it appears that there is a hidden or unseen byte or at least that is how it appears in the context? Can someone explain to me in simple terms how I can extract a unique that is 100% different from one ESP32 chip to the next?

HUGE THANK YOU TO THE PERSON THAT CAN HELP ME...
SEND ME YOUR ADDRESS I WILL HAVE PIZZA ON ITS WAY!

[ESP_Sprite]

How are you reading out that MAC address?