Ratio=16(0b10000)这个值直接被写到ADC_CFGR2的bit【4:0】,而这个寄存器的bit【4:2】就是控制ratio的
手册上
Bits 4:2 OVSR[2:0]: Oversampling ratio
This bitfield is set and cleared by software to define the oversampling ratio.
000: 2x
001: 4x
010: 8x
011: 16x
100: 32x
101: 64x
110: 128x
111: 256x