Abstract: Methods and apparatus are provided to facilitate debugging of a system with a hung data bus. A register scan chain is used to read data from logic blocks of the hung system. The scan chain is also used to write data into the logic blocks, possibly resetting a subset of those blocks or otherwise causing them to exit the hung state. The resetting may terminate the hung instruction in a manner that allows subsequent instructions to be executed, including entry into debug mode.

Abstract: A programmable logic integrated circuit has an embedded processor with a watchdog timer circuit. The watchdog timer circuit is used to detect software or hardware failures. In one implementation, the watchdog timer circuit includes a counter register that advances (e.g., incremented or decremented) with each clock. To prevent the watchdog timer circuit from becoming triggered, the watchdog timer circuit should be reset or reloaded by software. For example, the count register may be reset to a value to start the count over. If the count register is allowed to count to a final or maximum value, the watchdog timer circuit will become triggered, generating a triggered signal that causes the programmable logic integrated circuit to be reset. A reset causes a reloading of the configuration data used to program the programmable logic and embedded processor portions of the integrated data. The configuration data may be stored in an external nonvolatile storage memory.

Abstract: A method and apparatus for configuring a digital system having a programmable logic device and embedded logic from a configuration source that supplies a single serialized configuration bit stream for configuring both the programmable logic device and the embedded logic.

Abstract: A programmable logic integrated circuit has an embedded processor with a watchdog timer circuit. The watchdog timer circuit is used to detect software or hardware failures. In one implementation, the watchdog timer circuit includes a counter register that advances (e.g., incremented or decremented) with each clock. To prevent the watchdog timer circuit from becoming triggered, the watchdog timer circuit should be reset or reloaded by software. For example, the count register may be reset to a value to start the count over. If the count register is allowed to count to a final or maximum value, the watchdog timer circuit will become triggered, generating a triggered signal that causes the programmable logic integrated circuit to be reset. A reset causes a reloading of the configuration data used to program the programmable logic and embedded processor portions of the integrated data. The configuration data may be stored in an external nonvolatile storage memory.

Abstract: Methods and apparatus are provided to insert errors into digital data. The errors can be inserted into the data itself, or into the corresponding error correcting code bits. The invention comprises a register, whose contents are combined with data using exclusive-OR circuitry. By varying the contents of that register, an error can be inserted into a specific bit in a particular data word, or into multiple bits in the same word.

Abstract: A microprocessor-based system includes multiple peripherals, which can be accessed by the microprocessor over a system bus, with the aid of address decoding logic. Depending on the required functionality of the system at any time, one or more of the peripherals can be disabled. When a peripheral device is disabled, the address decoding logic of the system is modified to ensure that no attempts are made to access that peripheral device.

Abstract: A memory controller can perform prefetching, in a way which increases the efficiency with which data can be read from an external memory. More specifically, the memory controller operates such that it performs prefetching only under certain conditions, which are chosen such that there is a high probability that the data requested in the prefetching operation will be the data which is next required. The memory controller may be implemented in a programmable logic device (PLD), and be optimized for retrieving data from an external flash or SRAM memory device, which is used for storing configuration data for the PLD. By examining a read request, it is possible to determine whether a prefetching operation can be performed, with a high probability that it will be the required data which is prefetched.

Abstract: Methods and apparatus for programmable logic devices including embedded processors having a dual-port SRAMs. A programmable logic integrated circuit includes a programmable logic portion having a plurality of logic elements, programmably configurable to implement user-defined combinatorial or registered logic functions, and an embedded processor portion coupled to the programmable logic portion. The embedded processor portion includes a processor, and a memory block coupled to the processor. The memory block includes a first plurality of memory cells for storing data, a second plurality of memory cells for storing data, a first port coupled to the first and second pluralities of memory cells, a second port coupled to the first and second pluralities of memory cells, and an arbiter coupled to the first port and the second port.

Abstract: In a programmable logic device system, including a programmable logic device, a configuration memory device, for storing configuration information, and a host computer system, for generating updated configuration information, the programmable logic device has a JTAG port, for connection to said host computer system, for receiving said updated configuration information, a JTAG port controller, operatively connected to the first JTAG port, and an SPI interface, for connection to said configuration memory device. The JTAG port controller comprises a scan chain, for controlling said SPI interface on the basis of information received from said host computer system. This allows a user of the host computer system to transfer updated configuration data to the configuration memory device by means of a connection from the host computer system to the JTAG port of the programmable logic device.

Abstract: A programmable logic device includes a routing structure, which takes the form of multiple distributed OR gates, which are positioned within the device to allow signals to be input from spaced apart logic elements, and present the input signals to other logic elements, which, again, may be spaced apart throughout the device. Each of the distributed OR gates, and its connections to the other logic elements, acts as a multiplexer. Sufficient of these distributed OR gates are provided to allow a bus structure to be implemented within the device. Since the OR gates are provided separately from the logic elements of the programmable logic device, the required bus structure can be implemented more efficiently.

Abstract: A programmable logic device includes a gate array formed from programmable logic elements, and at least one address decoder structure. The address decoder has a first stage, for receiving bits of an address, and for masking out a first group of least significant bits of said address; a second stage, for comparing a second group of most significant bits of said address with respective comparison bits; and a third stage, for providing an output when all of the bits in said second group of bits of said address match their respective comparison bits. Thus, the address decoder can determine when a received address falls within a range of addresses associated with the address decoder. Multiple address decoders may be provided at spaced apart locations within the gate array, and one address decoder can be associated with each slave device implemented in the gate array. The programmable logic device may be used to implement a bus structure, with a bus master which may be in the form of an embedded processor.

Abstract: A reconfigurable programmable logic system including a programmable logic device and an associated processor is configured using a configuration file including (a) instructions for configuring the programmable logic device as one or more peripherals to be used by the processor, and (b) a list of the peripherals to be configured in the programmable logic. The processor uses the peripheral data from the configuration file to load the appropriate drivers, create all necessary instances of the drivers and optionally to pass parameters for any necessary initial command after each driver is loaded. Optionally, each time the system is configured, any previously loaded drivers are first unloaded.

Abstract: A programmable logic device (PLD) includes a memory controller. The memory controller includes a first controller that communicates via a shared interface with a first memory external to the PLD. The memory controller also includes a second controller that communicates via the shared interface with a second memory external to the PLD. The PLD further includes an arbitration circuitry. The arbitration circuitry is configured to arbitrate ownership of the shared interface by the first and second controllers.

Abstract: A technique synchronizes logic signals captured in a PLD portion of a PLD system having both a microprocessor and PLD circuitry with executed instructions captured from a microprocessor portion. One or more signal lines connects the microcontroller portion with the PLD portion for transmitting signals between the two portions corresponding to debug operations in each portion. Conventional electronic circuits employing microprocessors and PLD's use independent debugging techniques, either of which are incapable of reflecting the complete state of the circuit at a selected time. Combined processor and PLD systems employ independent clocks for each portion, thus creating additional problems in synchronizing logic state traces in the PLD with the microprocessor instruction traces. The present invention provides a direct signals from the PLD portion to the microcontroller portion upon the occurrence of events relating to debugging and debug modes of the microprocessor.

Abstract: A method and apparatus for configuring a digital system having a programmable logic device and embedded logic from a configuration source that supplies a single serialized configuration bit stream for configuring both the programmable logic device and the embedded logic.