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espressif / esp-adf

Espressif Audio Development Framework
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Suspected RF interference of bluetooth with I2S audio (lyrat_v4_3) (AUD-1101) #289

Open sylvanarama opened 4 years ago

sylvanarama commented 4 years ago

When playing audio from aux in to bluetooth out (using the board as a bluetooth source) there is a persistent low clicking/buzzing.

To find the source, I have two pipelines running: aux_in > ES8388 ADC > i2s_read > i2s_write > ES8388 DAC > headphones (i2s_read multi-output) > raw > bluetooth

The audio on the wired headphones is clear until I start bluetooth pairing or connecting, then there is a high-pitched whine for the duration of pairing or connecting. Once connected, the whine disappears, to be replaced by the low buzzing. This persists even when the bluetooth pipeline is not running and not connected to i2s_read. The noise is still present when there is no audio coming in from AUX.

Also, the buzzing can be heard on both the wired headphones and bluetooth headphones.

The whine is also present when the board is connecting/disconnecting as an audio sink, though the buzz is more of a click, reduced to approx 2 per second.

Is it possible that transmissions from the antenna are causing noise on the i2s bus? If so, is there any way to reduce this? And if not, are there any other possible causes?

Thank you for your help in advance!

YoSmartInc commented 2 years ago

Encountered a similar problem, RF(915M) interference with I2S. Specifically, IOs(mck，sck，rlck) of i2s lead to a reduction in the RX sensitivity of RF.