Abstract: The present invention provides circuitry and methods for sharing I/O pins between a programmable logic portion and an embedded processor portion of a chip. The circuits in the programmable logic portion and the embedded processor portion can access data signals from and send data signals to the same I/O pins. The data signals are multiplexed to control access to the shared I/O pins. The multiplexers may be controlled by a control signal that determines when particular I/O pins are accessed by the programmable logic portion and the embedded processor portion. Control signals that configure the associated I/O pin circuitry to the correct I/O standard are also multiplexed by the shared I/O circuitry of the present invention. Signals received at the shared I/O pins that are transmitted to the embedded processor portion may be concurrently sent to snoop circuitry within the programmable logic portion.

Abstract: A user logic design for a mask-programmable logic device (“MPLD”) may be designed on a comparable or compatible user-programmable logic device (“UPLD”) and migrated to the MPLD, or may be designed directly on an MPLD. If the design is designed on a UPLD, the constraints of the target MPLD—i.e., differences between the devices—are taken into account so that the migration will be successful. If the design is designed directly on an MPLD, constraints of a comparable compatible UPLD are taken into account if the user indicates that the design will be migrated to the UPLD for testing. This means that when a logic design is intended to be migrated back-and-forth between a UPLD and an MPLD, only the intersection of features can be used. To facilitate migration, fixed mappings between pairs of devices may be created.

Abstract: A programmable logic array integrated circuit has a number of programmable logic modules which are grouped together in a plurality of logic array blocks (“LABs”). The LABs are arranged on the circuit in a two dimensional array. A conductor network is provided for interconnecting any logic module with any other logic module. In addition, adjacent or nearby logic modules are connectable to one another for such special purposes as providing a carry chain between logic modules and/or for connecting two or more modules together to provide more complex logic functions without having to make use of the general interconnection network. Another network of so-called fast or universal conductors is provided for distributing widely used logic signals such as clock and clear signals throughout the circuit. Multiplexers can be used in various ways to reduce the number of programmable interconnections required between signal conductors.

Abstract: In a programmable logic device having dedicated multiplier circuitry, some of the scan chain registers normally used for testing the device are located adjacent input registers of the multipliers. Those scan chain registers are ANDed with the input registers, and can be loaded with templates of ones and zeroes. This allows, e.g., subset multiplication if the least significant bits are loaded with zeroes and the remaining bits are loaded with ones. The multipliers preferably are arranged in blocks with other components, such as adders, that allow them to be configured as finite impulse response (FIR) filters. In such configurations, the scan chain registers can be used to load filter coefficients, avoiding the use of scarce logic and routing resources of the device.

Abstract: A technique provides an on-chip voltage to a core portion of a programmable logic integrated circuit by way of a conversion transistor. The on-chip voltage may be a reduced internal voltage, less than the VCC of the integrated circuit. In an embodiment, the layout (or physical structure) of the conversion transistor is distributed surrounding the core portion. By providing the core with a reduced voltage, the integrated circuit may interface with other integrated circuits compatible with different voltage levels.