基本用法
import pyb
adc = pyb.ADC(Pin('Y11')) # create an analog object from a pin
adc = pyb.ADC(pyb.Pin.board.Y11)
val = adc.read() # read an analog value
adc = pyb.ADCAll(resolution) # creale an ADCAll object
val = adc.read_channel(channel) # read the given channel
val = adc.read_core_temp() # read MCU temperature
val = adc.read_core_vbat() # read MCU VBAT
val = adc.read_core_vref() # read MCU VREF
pyb.ADC（pin）
通过GPIO定义一个ADC
pyb.ADCAll(resolution)
定义ADC的分辨率，可以设置为8/10/12
adc.read()
读取adc的值，返回值与adc分辨率有关，8位最大255，10位最大1023，12位最大4095
adc.read_channel(channel)
读取指定adc通道的值
adc.read_core_temp()
读取内部温度传感器
adc.read_core_vbat()
读取vbat电压
vback = adc.read_core_vbat() * 1.21 / adc.read_core_vref()
adc.read_core_vref()
读取vref电压（1.21V参考）
3V3 = 3.3 * 1.21 / adc.read_core_vref()
adc.read_timed(buf, timer)
以指定频率读取adc参数到buf
buf，缓冲区
timer，频率（Hz）
使用这个函数会将ADC的结果限制到8位
adc = pyb.ADC(pyb.Pin.board.X19) # create an ADC on pin X19
buf = bytearray(100) # create a buffer of 100 bytes
adc.read_timed(buf, 10) # read analog values into buf at 10Hz
#this will take 10 seconds to finish
for val in buf: # loop over all values
print(val) # print the value out