请问CC3200的ADC采样频率可以设置吗

Voltage is 0.557471
Voltage is 0.573877
Voltage is 0.578662
Voltage is 0.575244
Voltage is 0.560547
Voltage is 0.574561
Voltage is 0.573535
Voltage is 0.559863
Voltage is 0.559521
Voltage is 0.555420
Command Usage
--------------
adcdemo
Parameters
--------------
adc_inputpin - Pin to which Analog signal is connected [58|59|60]
-------------------------------------------------------------------------
用的是官方给的sdk例程里面的adc
我没有接任何输入信号，但其adc采集有电压是有的
这是怎么回事
请技术人员给出解答