GPIO and HSIO can be configured as a Schmitt Trigger input that, when enabled, exhibits a hysteresis that helps to filter out the noise at the receiver and prevents double-glitching caused by noisy input edges.
The following table lists the I/O standards that support the Schmitt Trigger feature. For more information about hysteresis values for different I/O standards when Schmitt Trigger mode is enabled, see respective PolarFire FPGA Datasheet or PolarFire SoC Advance Datasheet.
| I/O Standards | Supported I/O Types | Options |
|---|---|---|
| LVTTL LVCMOS33 LVCMOS25 PCI |
GPIO (input only) | ON OFF |
| LVCMOSI15 LVCMOSI18 |
HSIO (input only) | ON OFF |
Schmitt Trigger mode is enabled by using the I/O attribute editor in Libero SoC or by using the following PDC command:
set_io -schmitt_trigger <value>The value can be set as ON or OFF.