Common Mode Voltage (Vcm) Settings

GPIO and HSIO inputs allow common mode settings for differential receivers. It assists in preventing common-mode mismatches between devices.

The following table lists the programmable differential termination control support and settings. For more information about common mode voltage levels for various I/O standards, see respective PolarFire FPGA Datasheet or PolarFire SoC Advance Datasheet.

Table 1. Programmable Differential Termination Control
I/O Standards Supported I/O Types Differential Termination Type1
SSTL18 GPIO, HSIO Off, Low, Mid
HSUL18 GPIO, HSIO Off, Low, Mid
SSTL15 GPIO, HSIO Off, Low, Mid
HSTL15 GPIO, HSIO Off, Low, Mid
SSTL135 HSIO Off, Low, Mid
HSTL135 HSIO Off, Low1, Mid
HSUL12I HSIO Off, Low, Mid
HSTL12 HSIO Low, Mid
POD12 HSIO Off, Low, Mid
SSTL25 GPIO

SLVS25 GPIO, HSIO MID (HSIO)

Low, Mid (GPIO)

HCSL25 GPIO, HSIO MID (HSIO)

Low, Mid (GPIO)

SLVSE GPIO, HSIO Off, Mid (HSIO)

Off, Low, Mid (GPIO)

PPDS25 GPIO, HSIO Mid (HSIO)

Off, Low, Mid (GPIO)

MLVDSE GPIO Off, Low, Mid
BUSLVDS GPIO Off, Low, Mid
LVPECL GPIO Low, Mid
LVDS GPIO, HSIO Mid (HSIO)

Off, Low, Mid (GPIO)

RSDS GPIO, HSIO Mid (HSIO)

Off, Low, Mid (GPIO)

MINILVDS GPIO, HSIO Mid (HSIO)

Off, Low, Mid (GPIO)

(1) For more information about low and mid differential termination types, see respective PolarFire FPGA Datasheet or PolarFire SoC Advance Datasheet.  

The programmable differential termination control values can be programmed by using the I/O attribute editor in Libero SoC or by using the following PDC command:

set_io –vcm_range <value>

Value can be set as listed in Table 1.