此子程序将进行AD转换和AD处理，处理后的12位AD值中低八位存放在 adc_buffer_low中，高四位存放在adc_buffer_hi寄存器的低四位-This subroutine will convert to AD and AD treatment, treated in the low 12-bit AD value stored in the adc_buffer_low eight, the high four storage registers in the low 4