Hello everyone,
I have a problem with the wifi and Bluetooth interfering with the speakers in the recent board i designed which causes a harsh and disturbing noise every time the controller attempts to connect with the wifi or Bluetooth device.
Is there any suggestion or viable solution to eliminate or mitigate the problem?
here is some description:
- the board contains arm-cortex MCU, ESP32 wifi-Bluetooth module, and MP3 player module next to ESP32 but not facing the antenna.
- the audio output is separated from the ESP32 with around 4 cm of distance and routed on the Top, and the audio signal gets amplified by a tda2230 power amplifier.
- Double side with ground planes on both sides connected using stretching vias.
- SPI and I2C signals are matched in length and with continuous grand plane underneath.

 

Bluetooth operates on the 2.4Ghz band and can interfere with wifi.

What is it like with the wifi turned off in the house?

 

@Dodgydave
The board is a containing Wifi-Bluetooth module for multi-way communication. when the board connects to either Bluetooth or wifi, the speaker which is connected to the board through an amplifier, is producing noticeable noise, but the noise caused by Bluetooth is different from the noise caused by wifi.
it doesn't produce any kind of noise of its not connected or attempt to connect

 

Is the noise continuous or intermittent? You need to figure out if it's RF being picked up by something on the board, or if it's noise in the power net; possibly the WiFi and/or BT module are putting noise onto the power net. Scope the power lines into your amplifier and mp3 module, and the audio inputs to the amplifier. See if you can determine which way the noise is getting into the system as a starting point. Also see if you can figure out the frequency of the noise, and the shape of the wave form. That might help you figure out where it's coming from. Lastly double check your amplifier and mp3 module circuit against the datasheet and make sure you've got the recommended noise filtering bits installed. Also check the RF parts against the datasheets and be sure you've followed their recommended layout, sometimes RF parts have specific layout requirements. Be sure your audio amplifier inputs are run as far away from the RF parts as is possible.