Abstract: Circuitry for locating the boundaries of bytes in a data stream is provided. The data stream typically has comma or header information that provides an indication of the byte boundaries. When circuitry detects this information, it can align the byte boundaries and thereby provide byte-aligned data to utilization circuitry (e.g., a programmable logic device). In accordance with this invention, circuitry can select different special characters for use in detecting the byte boundaries, where the special characters are different lengths. Circuitry aligns the byte boundaries based on the selected special character when enabled by a control signal. Once aligned, circuitry can provide a signal indicating which special character was used to align the boundaries. Another advantage of the invention is that it eliminates alignment problems associated with system latency. Circuitry automatically locks alignment to a first instance of a detected special character independent of an external control signal.

Abstract: A programmable logic device (“PLD”) includes high-speed serial interface (“HSSI”) circuitry. The HSSI circuitry includes clock signal circuitry that allows various components of the HSSI circuitry to be clocked in different ways to facilitate use of the HSSI circuitry to support a number of different communication protocols. Some of the HSSI clock signals may be routed through the clock distribution network of the associated PLD logic circuitry. The HSSI circuitry may include phase compensation buffer circuitry to compensate for possible phase differences across the interface between the HSSI circuitry and the associated PLD logic circuitry.

Abstract: Clock rate matching circuitry is provided to buffer data between two clock domains that may have slightly different frequencies. To facilitate supporting a wide range of different communication protocols, the clock rate matching circuitry includes dedicated control circuitry and is also associated with other circuitry that is capable of acting as control circuitry that can be used as an alternative to at least part of the dedicated control circuitry. For example, the dedicated control circuitry may be set up to support one or several industry-standard protocols. The other circuitry (which may be, for example, programmable logic circuitry) is available to support any of a wide range of other protocols, whether industry-standard or custom.

Abstract: A device such as a programmable logic device (“PLD”) includes circuitry for detecting the PPM frequency difference between two input clock signals. For example, this circuitry may accept a user-programmable PPM threshold value and output a signal when this threshold value is met.

Abstract: A serial interface for a programmable logic device substantially eliminates skew across multiple channels both in the receiver and in the transmitter. Even when the channels are independent (e.g., are in different quads), skew is substantially eliminated by monitoring to determine when all channels have reached their active states (i.e., in the case of receiver channels when all channels have achieved byte alignment and have received an alignment character, and in the case of transmitter channels when all transmit PLLs have locked), and only then allowing data to flow between the serial and parallel domains.

Abstract: In a programmable logic device, some or all of the parallel interconnect resources are replaced by serial interconnect resources within the device. Some or all of the functional blocks on the device are supplemented with serial interfaces. Although this makes the functional blocks more complex, it allows a significant reduction in the area consumed by interconnect resources. This translates into a significant reduction in device power consumption. The serial interfaces may operate synchronously from a global device clock (such as a PLL). In some cases, serial interfaces that are provided in the input/output blocks for external signalling can be omitted because the serial interfaces in the functional blocks can take over the external serial interface function as well, although in those cases the serial interfaces in the functional blocks would have to be more complex because they would have to be able to operate asynchronously with external devices.

Abstract: Eight-bit ten-bit (8B10B) coding is provided in a hard intellectual property (IP) block with the capability of supporting a greater range of data rates (e.g., data rates less than, equal to, and greater than 3.125 Gbps). Each channel of high speed serial interface circuitry includes receiver circuitry having two 8B10B decoders and transmitter circuitry having two 8B10B encoders. The receiver and transmitter circuitry can be configured to operate in one of three modes of operation: cascade mode, dual channel mode, and single channel mode.

Abstract: An integrated circuit like a programmable logic device (“PLD”) includes multiple channels of data communication circuitry. Circuitry is provided for selectively sharing signals (e.g., control-type signals) among these channels in groupings of various size so that the device can better support communication protocols that require various numbers of channels (e.g., one channel operating relatively independently, four channels working together, eight channels working together, etc.). The signals shared may include a clock signal, a FIFO write enable signal, a FIFO read enable signal, or the like. The circuit arrangements are preferably modular (i.e., the same or substantially the same from one channel to the next and/or from one group of channels to the next) to facilitate such things as circuit design and verification.

Abstract: Eight-bit ten-bit (8B10B) coding is provided in a hard intellectual property (IP) block with the capability of supporting a greater range of data rates (e.g., data rates less than, equal to, and greater than 3.125 Gbps). Each channel of high speed serial interface circuitry includes receiver circuitry having two 8B10B decoders and transmitter circuitry having two 8B10B encoders. The receiver and transmitter circuitry can be configured to operate in one of three modes of operation: cascade mode, dual channel mode, and single channel mode.

Abstract: Deserializer circuitry for high-speed serial data receiver circuitry on a programmable logic device (“PLD”) or the like includes circuitry for converting serial data to parallel data having any of several data widths. The circuitry can also operate at any frequency in a wide range of frequencies. The circuitry is configurable/re-configurable in various respects, at least some of which configuration/re-configuration can be dynamically controlled (i.e., during user-mode operation of the PLD).

Abstract: A programmable logic device (“PLD”) includes high-speed serial interface (“HSSI”) circuitry. The HSSI circuitry includes clock signal circuitry that allows various components of the HSSI circuitry to be clocked in different ways to facilitate use of the HSSI circuitry to support a number of different communication protocols. Some of the HSSI clock signals may be routed through the clock distribution network of the associated PLD logic circuitry. The HSSI circuitry may include phase compensation buffer circuitry to compensate for possible phase differences across the interface between the HSSI circuitry and the associated PLD logic circuitry.

Abstract: Serializer circuitry for high-speed serial data transmitter circuitry on a programmable logic device (“PLD”) or the like includes circuitry for converting parallel data having any of several data widths to serial data. The circuitry can also operate at any frequency in a wide range of frequencies, and can make use of reference clock signals having any of several relationships to the parallel data rate and/or the serial data rate. The circuitry is configurable/re-configurable in various respects, at least some of which configuration/re-configuration can be dynamically controlled (i.e., during user-mode operation of the PLD).

Abstract: A serial interface for a programmable logic device supports a wide range of data rates by providing a first number of channels supporting a first range of data rates and a second number of channels supporting a second range of data rates. The first range of data rates is preferably lower than the second range of data rates and preferably the first number of channels is higher than the second number of channels which preferably is 1. For backward compatibility with existing devices, the first number of channels in each interface preferably is four. Each channel preferably includes a physical medium attachment module and a physical coding sublayer module. Each of the higher-speed channels in the second number of channels preferably also includes a clock management unit, while the lower-speed channels in the first number of channels preferably share one or more clock management units.

Abstract: A data converter, or “gearbox,” for a padded protocol interface can perform a number of different conversions—e.g., between 64 and 66 bits, between 24 and 26 bits, or between 48 and 50 bits. This is accomplished by clocking the gearbox at different clock speeds, all derived from the same master clock (which may be recovered from the data in a receiver embodiment) using programmable dividers that allow the user to select the clock speed. When the conversion is not that one with the maximum width for which the gearbox is designed, unused bits are ignored. The converter can also find padding bits, for alignment purposes, in data of different widths, again ignoring unused bits when the data are not the widest for which the converter is designed.

Abstract: Phase locked loop circuitry operates digitally, to at least a large extent, to select from a plurality of phase-distributed candidate clock signals the signal that is closest in phase to transitions in another signal such as a clock data recovery (“CDR”) signal. The circuitry is constructed and operated to avoid glitches in the output clock signal that might otherwise result from changes in selection of the candidate clock signal.

Abstract: A serial interface for a programmable logic device provides multiple data rates in different channels by generating a central serial clock and providing at least one divider in each channel that can divide the central clock by different integer values. For additional variation in clock rate, two or more different central clocks can be provided, with each channel then being able to divide any of the central clocks to provide the desired local clock. Lower speed parallel clocks can be generated locally by further dividing the divided serial clock. Alternatively, the central serial clock or clocks may be divided centrally to provide a central parallel clock or clocks which can then be used locally as a local parallel clock.

Abstract: A serial interface for a programmable logic device can be operated according to various communications protocols and includes both a receiver portion and a transmitter portion. The receiver portion includes at least a word or byte alignment stage, a de-skew stage, a rate compensation or matching stage, a padded protocol decoder stage (e.g., 8B/10B decoder circuitry or 64B/66B decoder circuitry), a byte deserializer stage, a byte reorder stage, and a phase compensation stage. The transmitter portion includes at least a phase compensation stage, a byte deserializer stage, and a padded protocol encoder stage (e.g., an 8B/10B encoder circuitry or 64B/66B encoder circuitry). Each stage may have multiple occurrences of relevant circuitry. Selection circuitry, such as multiplexers, selects the appropriate stages, and circuitry within each stage, for the protocol being used.

Abstract: Improved communication, and an improved communication interface, between the core PLD fabric of a PLD and embedded IP building blocks resident therein is provided. A circuit according to the invention may include at least two different signal paths between the PLD core fabric and embedded IP building blocks. Either one, or both, of these two paths may be used for configuration and/or implementation of the embedded IP building blocks.

Abstract: A serial data interface for a programmable logic device includes a receiver that deserializes a plurality of channels of received serial data using a recovered clock signal or a phase-aligned received clock signal. Byte boundaries are initially assigned, perhaps arbitrarily, and the deserialized signal is sent to the programmable logic core of the programmable logic device. Programmable logic in the core monitors the byte boundaries on each channel based on the criteria, including any user-defined parameters, programmed into the logic. If a boundary misalignment is detected, a signal is send from the core to bit-slipping circuitry on that channel of the interface to adjust the boundary. The signal could instruct the bit-slipping circuitry to adjust the boundary by the number of bits needed to correct the alignment. Alternatively, the bit-slipping circuitry could operate iteratively, adjusting the boundary by one bit, each cycle, until the signal stops indicating misalignment.

Abstract: Eight-bit ten-bit (8B10B) coding is provided in a hard intellectual property (IP) block with the capability of supporting a greater range of data rates (e.g., data rates less than, equal to, and greater than 3.125 Gbps). Each channel of high speed serial interface circuitry includes receiver circuitry having two 8B10B decoders and transmitter circuitry having two 8B10B encoders. The receiver and transmitter circuitry can be configured to operate in one of three modes of operation: cascade mode, dual channel mode, and single channel mode.