Abstract: A communications parallel bus receiver interface having N data lines and method of operation. The parallel bus interface employs receiver redundancy at the bus level such that there are N+1 receiver devices. An input switching network is configured to receive and couple N parallel data signals along respective paths to corresponding parallel-configured bit receiver devices, and adapted to couple one received data signal to two adjacent bit receivers. A calibration device calibrates one of the two adjacent bit receivers, and a qualification device qualifies data decisions made during calibration processes performed by the calibration device. The method cycles through each of N+1 receivers to periodically recalibrate each receiver (one at a time) while N inputs are processed continuously and uninterrupted.

Abstract: Transferring data from a first clock domain to a second clock domain, wherein the second clock domain has a fixed clock frequency, and the first clock domain has a variable clock frequency. The first clock domain and the second clock domain operate in a synchronous mode when the variable clock frequency is equal to the fixed clock frequency, and in an asynchronous mode when the variable frequency is lower than the fixed frequency. A first buffer and a second buffer are used for a data transfer from the first clock domain to the second clock domain. The second clock domain comprises a multiplexor connected to the first buffer and the second buffer. The multiplexor forwards data from the first buffer further into the second clock domain in the synchronous mode and from the second buffer into the second clock domain in the asynchronous mode.

Abstract: A communications link includes multiple continuously calibrated parallel lines, wherein one or more lines are at least partially powered down while being continuously calibrated to reduce power consumption. In one aspect, at least N+1 lines (where N is the logical bus width) are periodically recalibrated, and at least one redundant line is powered down between calibrations. The redundant line could be either a true spare available for use as a replacement, or an extra line which carries functional data while other lines are being calibrated in turn. In another aspect, the logical bus width is variable, but does not exceed NMAX. When N<NMAX, lines not carrying functional data are partially powered down between calibrations.

Abstract: A communications parallel bus receiver interface having N+1 data lines and method of operation. The parallel bus interface employs receiver redundancy at the bus level such that there are N+1 receiver devices. One of the N+1 data signals comprising a spare data signal when a failure occurs in a corresponding channel transmitting one of N parallel data signals. An input switching network is configured to receive and couple N+1 parallel data signals along respective paths to corresponding parallel-configured bit receiver devices, and adapted to couple one received data signal to two or three adjacent bit receivers. A calibration device calibrates one of the two or three adjacent bit receivers, and a qualification device qualifies data decisions made during calibration processes performed by the calibration device. The method cycles through N+1 receivers for periodic recalibration of each receiver (one at a time) while N+1 inputs are processed continuously and uninterrupted.

Abstract: Isolation of faulty links in a transmission medium including a method that includes receiving an atomic data unit via a multi-link transmission medium that has a plurality of transmission links. An error condition is detected and it is determined that the error condition is isolated to a single transmission link. It is determined if the single transmission link has been isolated previously as a failing transmission link a specified number of times within an interval specified by a timer. If the single transmission link has been isolated previously as a failing transmission link a specified number of times within an interval specified by a timer then: identifying the single transmission link as a faulty transmission link; resetting the timer; and outputting an identifier of the single transmission link.

Abstract: A communications link of multiple parallel communications lines includes at least one redundant line. In a first aspect, the lines are periodically recalibrated one at a time while the others carry functional data. If a fault is detected, the faulty line is disabled and the remaining previously calibrated lines transmit functional data. In a second aspect, impending line malfunction is detected from anomalies during calibration. In a third aspect, line malfunction is detected from receiver circuit output by determining a logical lane upon which each detected error occurs, and by mapping the logical lane to a physical line currently carrying the logical lane data.

Abstract: Transferring data from a first clock domain to a second clock domain, wherein the second clock domain has a fixed clock frequency, and the first clock domain has a variable clock frequency. The first clock domain and the second clock domain operate in a synchronous mode when the variable clock frequency is equal to the fixed clock frequency, and in an asynchronous mode when the variable frequency is lower than the fixed frequency. A first buffer and a second buffer are used for a data transfer from the first clock domain to the second clock domain. The second clock domain comprises a multiplexor connected to the first buffer and the second buffer. The multiplexor forwards data from the first buffer further into the second clock domain in the synchronous mode and from the second buffer into the second clock domain in the asynchronous mode.

Abstract: A parallel data link includes a redundant line. A bank of switches permits any arbitrary line of the link to be enabled or disabled for carrying functional data, each line being dynamically calibrated in turn by disabling the line and allowing other lines to carry the functional data. The switches are located downstream of alignment mechanisms so that data input to the switches is compensated for data skew. Preferably, receiver synchronization circuitry in each line operates in a respective independent clock domain, while the switches and calibration mechanism operate in a common clock domain. Preferably, the receiver synchronization circuits provide an adjustable delay corresponding to a variable number of clock cycles to align the outputs of the receiver synchronization circuits with respect to one another, which can accommodate high data skew.

Abstract: A calibratable communications link includes multiple parallel lines. Calibration is performed at dynamically variable and/or interruptible intervals determined by an automated mechanism. Calibration is preferably initiated responsive to a command generated by an executable software process, which initiates calibration responsive to detection of a probable impending need as indicated by, e.g., temperature change, calibrated parameter drift, error rate, etc. Calibration is also preferably initiated according to probable minimal disruption of device function, as indicated by low activity level. Furthermore, in one aspect calibration may be temporarily suspended to transmit data and then resumed.

Abstract: A communications parallel bus receiver interface having N data lines and method of operation. The parallel bus interface employs receiver redundancy at the bus level such that there are N+1 receiver devices. An input switching network is configured to receive and couple N parallel data signals along respective paths to corresponding parallel-configured bit receiver devices, and adapted to couple one received data signal to two adjacent bit receivers. A calibration device calibrates one of the two adjacent bit receivers, and a qualification device qualifies data decisions made during calibration processes performed by the calibration device. The method cycles through each of N+1 receivers to periodically recalibrate each receiver (one at a time) while N inputs are processed continuously and uninterrupted.

Abstract: A communications parallel bus receiver interface having N+1 data lines and method of operation. The parallel bus interface employs receiver redundancy at the bus level such that there are N+1 receiver devices. One of the N+1 data signals comprising a spare data signal when a failure occurs in a corresponding channel transmitting one of N parallel data signals. An input switching network is configured to receive and couple N+1 parallel data signals along respective paths to corresponding parallel-configured bit receiver devices, and adapted to couple one received data signal to two or three adjacent bit receivers. A calibration device calibrates one of the two or three adjacent bit receivers, and a qualification device qualifies data decisions made during calibration processes performed by the calibration device. The method cycles through N+1 receivers for periodic recalibration of each receiver (one at a time) while N+1 inputs are processed continuously and uninterrupted.

Abstract: A communications link includes multiple continuously calibrated parallel lines, wherein one or more lines are at least partially powered down while being continuously calibrated to reduce power consumption. In one aspect, at least N+1 lines (where N is the logical bus width) are periodically recalibrated, and at least one redundant line is powered down between calibrations. The redundant line could be either a true spare available for use as a replacement, or an extra line which carries functional data while other lines are being calibrated in turn. In another aspect, the logical bus width is variable, but does not exceed NMAX. When N<NMAX, lines not carrying functional data are partially powered down between calibrations.

Abstract: A communications link of multiple parallel communications lines includes at least one redundant line. In a first aspect, the lines are periodically recalibrated one at a time while the others carry functional data. If a fault is detected, the faulty line is disabled and the remaining previously calibrated lines transmit functional data. In a second aspect, impending line malfunction is detected from anomalies during calibration. In a third aspect, line malfunction is detected from receiver circuit output by determining a logical lane upon which each detected error occurs, and by mapping the logical lane to a physical line currently carrying the logical lane data.

Abstract: A parallel data link includes a redundant line. A bank of switches permits any arbitrary line of the link to be enabled or disabled for carrying functional data, each line being dynamically calibrated in turn by disabling the line and allowing other lines to carry the functional data. The switches are located downstream of alignment mechanisms so that data input to the switches is compensated for data skew. Preferably, receiver synchronization circuitry in each line operates in a respective independent clock domain, while the switches and calibration mechanism operate in a common clock domain. Preferably, the receiver synchronization circuits provide an adjustable delay corresponding to a variable number of clock cycles to align the outputs of the receiver synchronization circuits with respect to one another, which can accommodate high data skew.

Abstract: A parallel data link includes a redundant line. The redundant line permits one line to be calibrated while the others carry functional data, a switching mechanism enabling each line to be selected in turn for calibration. Control information for controlling the link, which is preferably for coordinating calibration activity, is communicated on the line selected for calibration. Preferably, the link is bi-directional, having a separate redundant line in each direction, enabling a bi-directional handshaking protocol to be used for communicating control information. Preferably, the lines selected for calibration are time-multiplexed to carry calibration patterns and control information at different time intervals.

Abstract: A memory buffer, memory system and method for power-on initialization and test for a cascade interconnect memory system. The memory buffer includes a bus interface to links in a high-speed channel for communicating with a memory controller via a direct connection or via a cascade interconnection through an other memory buffer. The interface is operable in a SBC mode and a high-speed mode. The memory buffer also includes a field service interface (FSI) slave for receiving FSI signals from a FSI master. In addition, the memory buffer includes logic for executing a power-on and initialization training sequence initiated by the memory controller.

Abstract: Isolation of faulty links in a transmission medium including a method that includes receiving an atomic data unit via a multi-link transmission medium that has a plurality of transmission links An error condition is detected and it is determined that the error condition is isolated to a single transmission link. It is determined if the single transmission link has been isolated previously as a failing transmission link a specified number of times within an interval specified by a timer. If the single transmission link has been isolated previously as a failing transmission link a specified number of times within an interval specified by a timer then: identifying the single transmission link as a faulty transmission link; resetting the timer; and outputting an identifier of the single transmission link.

Abstract: Shadow selection logic is used to select a driver bit position as a shadowed driver value, and line drivers to transmit data for the selected driver bit position and the shadowed driver value on separate link segments of a bus. In addition, shadow compare logic is used to compare a selected received value with a shadowed received value from the bus and identify a miscompare in response to a mismatch of the compare Shadow counters are used to count a rate of the miscompare relative to a bus error rate over a period of time. A defective link segment is identified in response to the rate of the miscompare within a predefined threshold of the bus error rate.

Abstract: Shadow selection logic is used to select a driver bit position as a shadowed driver value, and line drivers to transmit data for the selected driver bit position and the shadowed driver value on separate link segments of a bus. In addition shadow compare logic is used to compare a selected received value with a shadowed received value from the bus and identify a miscompare in response to a mismatch of the compare, and shadow counters to count a rate of the miscompare relative to a bus error rate over a period of time. A defective link segment is identified in response to the rate of the miscompare within a predefined threshold of the bus error rate.

Abstract: A method, apparatus, and computer instructions for managing a set of signal paths for a chip. A defective signal path within the set of signal paths for the chip is detected. Signals are re-routed through the set of signal paths such that the defective signal path is removed from the set of signal paths and sending signals using remaining data signal paths in the set of signal paths and using an extra signal path in response to detecting the defective signal path.