LVDS Tunneling Protocol and Interface IP User Guide: Agilex™ 5 FPGAs and SoCs
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6.3. UART Channel
The UART channel works similarly to the LL GPIO channel. The UART transmit data (TXD) and receive data (RXD) lines are oversampled at three times the LL GPIO sampling frequency, which is set by the LTPI frame generation frequency. The Difference in Sampling Frequencies between LL GPIO and UART Oversampling figure shows the difference in sampling frequencies between LL GPIO and UART oversampling.
UART sampling occurs every four system clock cycles within each frame to keep the sampling duty cycle close to 50%. This same sampling pattern is used when regenerating the UART data. The following figure shows the LTPI UART sampling distribution.