Games / Command flash cards / SDC (Synopsys Design Constraints) / Power and multiple voltages

Power and multiple voltages

Each card shows a command to explain. A missed card returns later in the round and starts the schedule over. A card answered correctly moves up the schedule and next appears after 1, 3, 7, then 21 days. Keys 1 to 4 choose an option, h shows a hint, and Enter moves on. A hint keeps the card where it is on the schedule. An ordering card is answered by clicking its items in order, and one wrong click ends it. Time values are in nanoseconds. Progress is stored in this browser.

SourceThese cards follow SDC (Synopsys Design Constraints) as implemented by OpenSTA, the open-source static timing analyzer used by OpenROAD, and each answer links to that command in the OpenSTA command reference. Commercial timers accept the same commands but can differ in details; where OpenSTA reads a command without acting on it, the card says so. Reference: OpenSTA command reference (OpenSTA on GitHub).

All 2 cards in this section, with answers

set_voltage 0.72 -object_list VDD

Sets the supply voltage on the power net VDD to 0.72 V.

Hint: The object is a power net. Ask what the number describes.

In a design with several supplies, each power net has its own voltage. -min sets a separate value for minimum-delay analysis. The command describes the supply; it does not create the net. OpenSTA reference
create_voltage_area -name VA_LOW -coordinate {100 100 400 300} [get_cells u_lp]

Reserves a region of the die for the cells of u_lp, on their own supply.

Hint: Coordinates are given. Ask whether this is a physical or an electrical statement.

It is a physical constraint for placement: the cells of u_lp go inside the region and all others stay out, so the region can have its own power grid. Timing analysis ignores it. Coordinates are in micrometres. OpenSTA reference