对q15 FFT输出错误

I am programming an STM32 cortex M4 microcontroller. I made a simple circuit to offset a sinusoid signal so that it varies (at its maximum output) from o to 3v3, basically I built a circuit to give the sinusoidal signal a DC offset because the mirocontroller's ADC does not support negative voltages. I am programming an STM32 cortex M4 microcontro