ESP32 Audible Noise on WiFi Transmit

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symaiotics
Posts: 1
Joined: Fri Mar 26, 2021 5:40 pm

ESP32 Audible Noise on WiFi Transmit

Postby symaiotics » Fri Mar 26, 2021 5:53 pm

Hey all,

I've adopted the ESP32 for one of my recent projects and am struggling to overcome an issue with audible noise from the ESP32 during wifi transmission. My prototype uses a MEMS microphone which is able to very audibly detect this noise. I have tried a number of different boards and ESP32 version (WROOM, WROVER, PICO) and the issues remain.

Here is a video I made of the issue.
https://www.youtube.com/watch?v=M6JhVIiudTI

Is there anyone else who has encountered this noise and figured out a solution?

Many thanks

Janak
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ESP_Sprite
Posts: 9730
Joined: Thu Nov 26, 2015 4:08 am

Re: ESP32 Audible Noise on WiFi Transmit

Postby ESP_Sprite » Sat Mar 27, 2021 5:38 am

Possibly this is because of any ceramic capacitors used on the board / in the module have a piezoelectric effect: they will flex a tiny little bit depending on the voltage applied to them, and if that voltage varies, they will produce some sound. I'm afraid I don't quite know a fix for this, although you could try to see if decoupling the 3.3V lines using some tantalum caps helps a bit.
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Vader_Mester
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Re: ESP32 Audible Noise on WiFi Transmit

Postby Vader_Mester » Sat Mar 27, 2021 9:28 am

Did you try disabling uart logging and see if that can cause this noise? I do not think that it's the wifi, that is causing the issue.
As you can see it varies by board design, so it's worth a shot checking these.

Code: Select all

task_t coffeeTask()
{
	while(atWork){
		if(!xStreamBufferIsEmpty(mug)){
			coffeeDrink(mug);
		} else {
			xTaskCreate(sBrew, "brew", 9000, &mug, 1, NULL);
			xSemaphoreTake(sCoffeeRdy, portMAX_DELAY);
		}
	}
	vTaskDelete(NULL);
}
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