CC2541的IO在那种情况下功耗最低？

三态，INPUT上拉，OUTPUT LOW，哪个功耗最低？

Unused I/O pins should have a defined level and not be left floating. One way to do this is to leave the pin unconnected and
configure the pin as a general purpose I/O input with pull-up resistor. Alternatively the pin can be configured as a general purpose I/O output

其实我想知道 在关机情况下 IO设置成三态还是 output low 功耗更低，官方的参考是 output low

output low是最优

Ideally, each GPIO pin will be unconnected, and therefore no leakage of current will occur. In real case, as with most boards, many of the GPIO pins are connected to peripheral devices, such as the LEDs, the buzzer, the accelerometer, and the buttons. To maximally reduce the current, all GPIO pins must be set to outputs at a low level. 

Tongersa

在关机情况下 IO设置成三态还是 output low 功耗更低，官方的参考是 output low

我觉得这个是要看你的原理图设计的。

比如，如果你外面有一个上拉电阻，那么，配成output low绝对是错误的。这个时候应该配成output high. 其次是input/PU

所以，归根结底的方法就是不要产生电压差，引入额外电流就对了。