Dedicated I/O Pins

Both the device families have a dedicated bank of I/Os. These I/Os are used for JTAG, SPI, and dedicated functions and pins supporting from 3.3 V to 1.8 V (Nominal) operation using the dedicated VDDI3 bank. Single-ended CMOS/TTL receiver input and output drivers are fixed in the device as listed in the following table.

Table 1. Dedicated I/Os—Fixed Settings
Dedicated I/Os Signal	Direction	Hot Swap	Pull Mode	Clamp	Hysteresis	Drive Strength
SCK	BIDI	Yes	OFF	OFF	ON	n/a
SS	BIDI	Yes	OFF	OFF	ON	n/a
SDO	OUT	Yes	OFF	OFF	OFF	8 mA
TDO	OUT	Yes	OFF	OFF	OFF	12 mA
TMS	IN	No	pull up	OFF	ON	n/a
TDI	IN	No	pull up	OFF	ON	n/a
TCK	IN	Yes	OFF	OFF	ON	n/a
TRSTB	IN	No	pull up	OFF	ON	n/a
DEVRST_N	IN	No	pull up	OFF	ON	n/a
RESERVED	IN	No	pull up	OFF	ON	n/a
SDI	IN	Yes	OFF	OFF	ON	n/a
IO_CFG_INTF	IN	Yes	OFF	OFF	ON	n/a
SPI_EN	IN	Yes	OFF	OFF	ON	n/a

Note: These signals cannot be altered or programmed with Libero SoC.

The five dedicated inputs—TDI, TMS, TRSTB, DEVRSTB, and RESERVED—do not support hot swap. The SDI pin does not have an on-chip weak pull-up due to the following reasons:

There may be multiple SPI interfaces connected on the board yielding too many parallel weak pull ups.
If SPI is not used in the system, Microchip has defined how the pin must be connected using the PPAT file.

For more information, see PolarFire FPGA and PolarFire SoC FPGA Programming User Guide.