TXT frame status
It will be good to provide additional status signals on the TXT Buffers. The actual implementation provides only "empty bit" on the buffer. This pretty much fills the function of the "busy bit" since the "empty bit" is set to 1 when the frame is sucesfully transmitted! If it is transmitted OK, then no problem.
The new implementation should provide next bit "TX OK" which signalizes that the frame was transmitted without problem.