Aspects of the disclosure provide for an apparatus. In some examples, the apparatus includes a clock generator, a clock data recovery (CDR) circuit, a state machine, and an adder. The clock generator is configured to determine a sampling clock based on a received input clock and a clock offset. The CDR circuit is configured to determine a phase of the input clock and determine CDR codes based on the determined phase and sampled data. The state machine is configured to record a first CDR code of the CDR codes at a first time, record a second CDR code of the CDR codes at a second time subsequent to the first time, and determine a calibrated offset based on the first CDR code and the second CDR code. The adder is configured to determine the clock offset according to the CDR codes and the calibrated offset.

One embodiment relates to a transmitting device, a receiving device, and the like for preventing increases in the number of communication links, power consumption, and circuit layout area. The transmitting device includes a high-speed signal generator, a low-speed signal generator, and a signal superimposing unit. The high-speed signal generator generates a high-speed signal having a limited frequency band. The low-speed signal generator generates a low-speed signal having a frequency lower than the frequency band of the high-speed signal. The signal superimposing unit outputs a superimposed signal of the high-speed signal and the low-speed signal. The receiving device includes a signal separator and a recovery unit. The signal separator separates the received signal into the high-speed signal and the low-speed signal. The recovery unit performs frequency tracking based on the separated low-speed signal and performs phase tracking based on the separated high-speed signal.

A receiving link device includes a receiver (RX) to receive a data signal from a transmitting link device, the receiver including an equalizer to detect RX tap values and a processing device coupled to the receiver, the processing device to perform operations including: programming the receiver with information related to target RX tap values that are associated RX pre-cursors or RX post-cursors; detecting, using the equalizer, that an RX pre-cursor value is greater or less than a target RX tap value; generating, based on the detecting, a tap message including an up or a down command to decrease or increase a corresponding transmitter (TX) pre-cursor value of the transmitting link device; and causing the tap message to be provided to a local transmitter to be transmitted to a remote receiver of the transmitting link device, which causes the transmitting link device to adjust the corresponding TX pre-cursor value.

A receiving link device includes a receiver (RX) to receive a data signal from a transmitting link device, the receiver including an equalizer to detect RX tap values and a processing device coupled to the receiver, the processing device to perform operations including: programming the receiver with information related to target RX tap values that are associated RX pre-cursors or RX post-cursors; detecting, using the equalizer, that an RX pre-cursor value is greater or less than a target RX tap value; generating, based on the detecting, a tap message including an up or a down command to decrease or increase a corresponding transmitter (TX) pre-cursor value of the transmitting link device; and causing the tap message to be provided to a local transmitter to be transmitted to a remote receiver of the transmitting link device, which causes the transmitting link device to adjust the corresponding TX pre-cursor value.

Systems and methods for asynchronous communication are disclosed. For example, a method for asynchronous communication includes encoding, by a transmitter circuit and according to a first clock signal, a bit sequence by converting a one-bit in the bit sequence into a first sequence and a zero-bit in the bit sequence into a second sequence. A length of the first sequence and a length of the second sequence differ by at least three bits. The method also includes communicating, by the transmitter circuit, the first sequence and the second sequence to a receiver circuit that decodes the first sequence and the second sequence according to a second clock signal that is independent of the first clock signal.

Systems and methods for asynchronous communication are disclosed. For example, a method for asynchronous communication includes encoding, by a transmitter circuit and according to a first clock signal, a bit sequence by converting a one-bit in the bit sequence into a first sequence and a zero-bit in the bit sequence into a second sequence. A length of the first sequence and a length of the second sequence differ by at least three bits. The method also includes communicating, by the transmitter circuit, the first sequence and the second sequence to a receiver circuit that decodes the first sequence and the second sequence according to a second clock signal that is independent of the first clock signal.

A receiving link device includes a receiver (RX) to receive a data signal from a transmitting link device, the receiver including an equalizer to detect RX tap values and a processing device coupled to the receiver, the processing device to perform operations including: programming the receiver with information related to target RX tap values that are associated RX pre-cursors or RX post-cursors; detecting, using the equalizer, that an RX pre-cursor value is greater or less than a target RX tap value; generating, based on the detecting, a tap message including an up or a down command to decrease or increase a corresponding transmitter (TX) pre-cursor value of the transmitting link device; and causing the tap message to be provided to a local transmitter to be transmitted to a remote receiver of the transmitting link device, which causes the transmitting link device to adjust the corresponding TX pre-cursor value.

A receiving link device includes a receiver (RX) to receive a data signal from a transmitting link device, the receiver including an equalizer to detect RX tap values and a processing device coupled to the receiver, the processing device to perform operations including: programming the receiver with information related to target RX tap values that are associated RX pre-cursors or RX post-cursors; detecting, using the equalizer, that an RX pre-cursor value is greater or less than a target RX tap value; generating, based on the detecting, a tap message including an up or a down command to decrease or increase a corresponding transmitter (TX) pre-cursor value of the transmitting link device; and causing the tap message to be provided to a local transmitter to be transmitted to a remote receiver of the transmitting link device, which causes the transmitting link device to adjust the corresponding TX pre-cursor value.

Systems, apparatuses, and methods for utilizing training sequences on a replica lane are described. A transmitter is coupled to a receiver via a communication channel with a plurality of lanes. One of the lanes is a replica lane used for tracking the drift in the optimal sampling point due to temperature variations, power supply variations, or other factors. While data is sent on the data lanes, test patterns are sent on the replica lane to determine if the optimal sampling point for the replica lane has drifted since a previous test. If the optimal sampling point has drifted for the replica lane, adjustments are made to the sampling point of the replica lane and to the sampling points of the data lanes.

Systems, apparatuses, and methods for utilizing training sequences on a replica lane are described. A transmitter is coupled to a receiver via a communication channel with a plurality of lanes. One of the lanes is a replica lane used for tracking the drift in the optimal sampling point due to temperature variations, power supply variations, or other factors. While data is sent on the data lanes, test patterns are sent on the replica lane to determine if the optimal sampling point for the replica lane has drifted since a previous test. If the optimal sampling point has drifted for the replica lane, adjustments are made to the sampling point of the replica lane and to the sampling points of the data lanes.