when the data rate is 110kbps or 850kbps,the smart tx power will not work?so if I want to take smart tx mode,I have to make the data rate 6.8Mbps？？？？ is that right ?
Yes, Smart TX is only meaningful for short frames (frames smaller than 1 ms). If your frame is longer than 1ms, which is probable with slower rates, you can not increase power.
Alternatively, you can set the TX power differently for each frame.
So , if I set the Data Rate is 110kbps，but I make the frame less than 1ms. the smart tx is still meaningful. Rihgt???
I make it that the absolute minimum length for a 110 kbps packet us 893 us. That’s close enough to 1 ms that there isn’t any meaningful power boost possible.
Also it makes no sense to send a frame with a 110 kbps but a short preamble. If the medium is good enough to detect the frame with a short preamble, you can use faster rate.