Pin Descriptions
v1.1
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User Pins
I/O
User Input/Output
The I/O pin functions as an input, output, tristate, or bidirectional buffer. Input and output signal
levels are compatible with the I/O standard selected.
During programming, I/Os become tristated and weakly pulled up to VCCI. With VCCI, VMV, and VCC
supplies continuously powered up, when the device transitions from programming to operating
mode, the I/Os are instantly configured to the desired user configuration.
Unused I/Os are configured as follows:
Output buffer is disabled (with tristate value of high impedance)
Input buffer is disabled (with tristate value of high impedance)
Weak pull-up is programmed
GL
Globals
GL I/Os have access to certain clock conditioning circuitry (and the PLL) and/or have direct access to
the global network (spines). Additionally, the global I/Os can be used as regular I/Os, since they
have identical capabilities. Unused GL pins are configured as inputs with pull-up resistors.
example, if GAA0 is used for an input, GAA1 and GAA2 are no longer available for input to the
quadrant globals. All inputs labeled GC/GF are direct inputs into the chip-level globals, and the rest
are connected to the quadrant globals. The inputs to the global network are multiplexed, and only
one input can be used as a global input.
Refer to the I/O Structure section of the handbook for the device you are using for an explanation
of the naming of global pins.
FF
Flash*Freeze Mode Activation Pin
Flash*Freeze is available on IGLOO and ProASIC3L devices. It is not supported on ProASIC3/E
devices. The FF pin is a dedicated input pin used to enter and exit Flash*Freeze mode. The FF pin is
active-low, has the same characteristics as a single-ended I/O, and must meet the maximum rise and
fall times. When Flash*Freeze mode is not used in the design, the FF pin is available as a regular I/O.
For IGLOOe and ProASIC3EL only, the FF pin can be configured as a Schmitt trigger input.
When Flash*Freeze mode is used, the FF pin must not be left floating to avoid accidentally entering
Flash*Freeze mode. While in Flash*Freeze mode, the Flash*Freeze pin should be constantly
asserted.
The Flash*Freeze pin can be used with any single-ended I/O standard supported by the I/O bank in
which the pin is located, and input signal levels compatible with the I/O standard selected. The FF
pin should be treated as a sensitive asynchronous signal. When defining pin placement and board
layout, simultaneously switching outputs (SSOs) and their effects on sensitive asynchronous pins
must be considered.
Unused FF or I/O pins are tristated with weak pull-up. This default configuration applies to both
Flash*Freeze mode and normal operation mode. No user intervention is required.