How to set the gain of the pdm module in nrf52832

[?????]

As I don't know much about audio,I have trouble with the gain of the pdm module in nrf52832.Now I have used MP45DT02 as the digital microphone,but I just can't understand the gain about the pdm module in the datasheet.I have tried to change the gain value,but it seem to have no effect on the audio.It also has too much noise.Could you give me some advice?

[Jørn]

The PDM module of the nRF52832 converts the PDM signal to PCM. The gain set in the register should then alter the numerical value for each sample. How do you play the sound? Do you have a figure showing how you have connected your microphone and speaker to the nRF?

[?????]

According to the datasheet,I just connect the microphone with the PDM interface directly.I have transmited the PCM data to USB dongle,so PC can record the audio data with USB.However when I repalyed the audio,it sounded like a lot of noise. Yesterday I found that it lost data when I transmited the data with 2.4G.But I am not sure about that the lost data caused the noise.

[Jørn]

It would be interesting to know where the noise comes from. Are you able to store it somewhere else? Or output it to the pc and play it back there? That would eliminate any problems with the wireless transfer. Another possibility would be that the microphone generates the noise or is affected by noise on the board. Or that the noise bleeds in from somewhere as the chip is sampling the data. Are you running any power hungry hardware while receiving data?