WIFI Issues with ESP32-S3-WROOM-1 modules that don't have a CMIIT ID

[tonystuart]

I use generic ESP32-S3-DevKitC boards as a sub-assembly in a product. These boards have an ESP32-S3-WROOM-1 module on them. I source them from a number of suppliers.

On some of these boards the WIFI doesn't work properly. It successfully scans for Access Points, but won't connect to an Access Point. In the following photo, the board on the left doesn't work. The board on the right works.

ESP32-S3-DevKitC-WIFI-Issues.2024-09-18a.jpg (93.56 KiB) Viewed 1111 times

I found an earlier topic that describes a problem with being able to scan for Access Points but not connect:

viewtopic.php?t=32109

This earlier topic suggests touching the WIFI antenna with a finger while connecting. This works with my problem boards as well.

Looking at my boards carefully, I see a pattern. The boards that don't work have different markings on the ESP32-S3-WROOM-1 module than those that do work. In particular, the CMIIT ID is empty on the boards that don't work.

Also the onboard antenna on the non-working board on the left looks like a typical Meandered Inverted F Antenna (MIFA) while the antenna on the working board on the right has an extra meander.

I am using Full RF Calibration as described here:

https://docs.espressif.com/projects/esp ... ation.html

And here are the WIFI PHY settings from my sdkconfig:

Code: Select all

CONFIG_ESP_PHY_CALIBRATION_AND_DATA_STORAGE=y
# CONFIG_ESP_PHY_INIT_DATA_IN_PARTITION is not set
CONFIG_ESP_PHY_MAX_WIFI_TX_POWER=20
CONFIG_ESP_PHY_MAX_TX_POWER=20
CONFIG_ESP_PHY_REDUCE_TX_POWER=y
CONFIG_ESP_PHY_ENABLE_USB=y
# CONFIG_ESP_PHY_ENABLE_CERT_TEST is not set
# CONFIG_ESP_PHY_RF_CAL_PARTIAL is not set
# CONFIG_ESP_PHY_RF_CAL_NONE is not set
CONFIG_ESP_PHY_RF_CAL_FULL=y
CONFIG_ESP_PHY_CALIBRATION_MODE=2

This leaves me with a number of questions:

• Are ESP32-S3-WROOM-1 modules produced only by Espressif or by many suppliers?
• What does the missing CMIIT ID mean? Is this an early version of the board? Should it even be available?
• Is there a way to configure the WIFI or PHY to work around this problem?

Any ideas?

Thanks!

[MicroController]

• Is there a way to configure the WIFI or PHY to work around this problem?

On some -C3 "Supermini" boards I found that I had to actually reduce the WiFi TX power from the default (20dBm?) (used esp_wifi_set_max_tx_power()) to be able to connect to a network. Probably due to a "sub-optimal" matching network and/or antenna on the board. IIRC, I could only go up to 11 or 13dBm before connection issues appeared. May be worth trying out.

[tonystuart]

Thanks... I'll give that a try.

Update: I tried reducing the max tx power and it connects. Very interesting... and a bit counterintuitive (at least for me)!