ESP8684-DevKitM-1-H4X RF failure

[mitchk]

I recently purchased an ESP8684-DevKitM-1-H4X from the "Espressif Store" on Amazon.com (USA). The board was functional in that I could upload and run code (i.e. hello world works just fine) but any code using the RF front end would fail. Anything I have tried using Wi-Fi or BLE doesn't work. I don't get any debug error messages it just fails to function. I thought I just got unlucky with a chip with a bad RF frontend so I ordered a second one. That one fails in the exact same way as the first. I'm curious if anyone else has any experience with this particular development board and has seen the same. I have other chip variants on hand (ESP32, ESP32-C3) that function as expected.

[Sprite]

Feels like a brownout issue... have you tried a different USB cable, or using / not using a (powered) USB hub?

[mitchk]

Thanks for the idea to check but I don't think it is a power issue. To be sure I tried powering the ESP8486 dev kit with a bench power supply. I get the same RF failure. I'm currently using the STATION example from the ESP-IDF as my test code. I then ran the same STATION example on a custom ESP32-C3 board powered with the same bench power supply setup and the ESP32-C3 board could successfully connect to the network.

[mitchk]

I finally found the issue with my ESP8684 modules. It was the main XTAL frequency. It was 40MHz by default in menuconfig but these modules need 26MHz. With the wrong XTAL frequency all of the code still seemed to be running normally only the RF functions were failing.