52832 ADC just do samle one time

Hi,

I'm using the ADC of nRF52832 on nRF5 SDK V12.2. The setting as attachment. I found that it just do sample one time. But I have use timer to call nrf_drv_saadc_sample() to the SAADC sample task every second. However, I just can see one adc result and the result is correct. Could you help me have a look? Thanks.

ADC.txt

main.c