os: ucosiii + LWIP
PIT0 -> DMA0
DMA0->ADC0 DMA0 transfer command change adc channel and trigger adc conver.
ADC0->DMA8 transfer the result to buffer.
set DMA0 priority to 0;
set DMA8 priority to 8;
ADC convert rate:25kps/per channel.
adc convert data send to PC by ethernet.
some times adc sample data is abnormal, have glitch， sometimes is normal, how to solve this problem?