CC1312R: when I can use Easylink_getRSSI to get RSSI?

Part Number: CC1312R

Tool/software:

我在项目中有双向数据通信,需要检测空中是否有设备在发送,用了Easylink getRSSI, (在收到数据后,想要启动发送前去判断) 。
I have two-way data communication in my project, and need to detect whether there is a device sending in the air, using Easylink_getRSSI (after receiving the data, I need to judge before starting a sending).
我的理解是收到数据后, RF应该到空闲状态了。
My understanding is that after receiving the data, RF should be in idle state.
这个时候是否要再次切换到RX状态,去获取RSSI还是直接获取RSSI就可以用?
Do I need to switch to the RX state again to get RSSI or get RSSI directly in idle state?

And I get error some times after Rx done immediately. If a make a 1 mS delay, it will no error. It is needed a short delay after RX done?