SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
The steps followed by the idle-line mode:
In IDLE mode, if the SCI is taking greater than 10 bit periods to read all the RXDATA from the FIFO, the SCI can miss the immediate block start to be detected.
The RXWAKE logic asserts only one time when the SCI identifies 10 bit periods of IDLE. The SCI does not assert again if RXBUF is read (which clears the WAKE condition) even if the line continues to be idle after RXBUF read.
So, if the ISR is taking more than 10 bit periods of time to read all the RXDATA from the FIFO using RXBUF, the SCI can miss to detect the next block start. This is applicable for both FIFO and Non-FIFO mode when the CPU takes greater than 10 bit clocks of SCI to read the data from RXBUF/FIFO.
To avoid this, either of the following is recommended: