SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
A "break" signal (also called a "break detect" or "break sequence") can be sent to the module to signal to the bus a specific condition. This break signal is defined as a low pulse of a certain amount of time, typically at least 1 packet wide (including a missed stop bit). The SCI has two main methods for detecting a "break" signal sent on the line, with certain limitations for each.
The first for break detect method involves reading the SCIRXST.BRKDT bit. A break condition that triggers the BRKDT bit occurs when the SCI receiver data line (SCIRXD) remains continuously low for at least 9.625 bits, beginning after a missing first stop bit. If the SCIRX line goes high at any point during the 9.625 bits then the SCI does not flag a break detect. To trigger the first stop bit missed, the typical method is to hold the RX line low for:
The second method for break detect is to instead use the SCIRXST.FE, SCIRXST.PE and SCIRXBUF.SAR bits to detect a break signal of 10 or 11 bits of low. ISR code can use the following combination of flags and received data to determine if a break detect occurred: