Visible to Intel only — GUID: fbv1661843301878
Ixiasoft
Visible to Intel only — GUID: fbv1661843301878
Ixiasoft
55.2.2. RS-232 Interface
The I/O buffers on Intel FPGA families do not comply with the RS-232 voltage levels and may be damaged if driven directly by signals from an RS-232 connector. To comply with the RS-232 voltage signaling specifications, an external level-shifting buffer is required (for example, Maxim MAX3237) between the FPGA I/O pins and the external RS-232 connector.
The Lightweight UART core uses a logic 0 for mark, and a logic 1 for space. An inverter inside the FPGA can be used to reverse the polarity of any of the RS-232 signals, if necessary.