Disclosed are systems, methods, and non-transitory computer-readable media for clock synchronization in half-duplex communication systems. Devices in a half-duplex system are synchronized based on time stamp values captured by each device that define a specified period of time that is of equal in length. The specified period of time spans two change-over periods to average the jitter and/or drift that occurs during each period. Each device uses these measured lengths to determine the variance in the rates at which the two internal clocks operates, which is then used to synchronizes the internal clocks of the two devices.

A retiming circuit module, a signal transmission system and a signal transmission method are disclosed. The retiming circuit module includes a path control circuit and a multipath signal transmission circuit. The multipath signal transmission circuit includes a plurality of parallel signal transmission paths. The path control circuit is configured to control the multipath signal transmission circuit to perform signal transmission between an upstream device and a downstream device based on a first parallel signal transmission path in the parallel signal transmission paths during a period of a handshake operation performed between the upstream device and the downstream device. The path control circuit is further configured to control the multipath signal transmission circuit to perform the signal transmission based on a second parallel signal transmission path in the parallel signal transmission paths after the handshake operation is finished.

A master device communicates with a slave device through an asynchronous serial communications link. The master device includes a single pad configured to communicate a command frame including an address and a data frame including data with the slave device via a single wire; and a processing circuit configured to generate an oversampling clock signal from a clock signal, to perform a synchronization process for selecting one of a plurality of clock phases of the oversampling clock signal, and to perform a sampling process for sampling an each bit value included in the data frame transmitted from the slave device using a clock phase at the same position as the clock phase selected during the synchronization process.

A data reception device comprises: a first data input for receiving a first data signal and a clock input for receiving a clock signal; and a stability detection circuit adapted to generate: a first error signal indicating when a data transition of the first data signal occurs during a first period at least partially before a first significant clock edge of the clock signal; and a second error signal indicating when a data transition of the first data signal occurs during a second period at least partially after the first significant clock edge of the clock signal; and a control circuit configured to generate a control signal for adjusting the sampling time of the first data signal based on said first and second error signals.

A baud-rate phase detector uses two error samplers. One error sampler is used to determine whether the sampling time is too early error detection. The other is used to determine whether sampling time is too late. The early error sampler is configured to use a first threshold voltage. The late error sampler is configured to use a second threshold voltage. By adjusting the voltage difference between the first threshold voltage and the second threshold voltage, the phase difference between the local timing reference clock and the transitions of the data signal may be adjusted. The phase difference between the local timing reference clock and the transitions of the data signal may be adjusted to improve or optimize a desired receiver characteristic such as bit error rate or signal eye opening.

LED drive control circuitry according to one embodiment outputs an LED drive control signal serving as driving a light emitting diode included in a photocoupler that performs insulation communication in synchronization with a reference clock signal. The LED drive control circuit includes a duty cycle changer that changes a duty cycle of the LED drive control signal in accordance with the reference clock signal and a signal synchronized with the reference clock signal.

Provided are a phase detection method and apparatus for a clock signal, and a communication device. A clock signal of a clock to be detected is sampled according to sampling periods set by a sampling clock; a phase angle value corresponding to a sampled clock signal in a current sampling period is obtained according to a mapping relationship between sampled signals and phase angle values; a phase difference corresponding to the current sampling period is subtracted from the phase angle value to obtain an initial phase value of the clock to be detected in the current sampling period, wherein the phase difference is a phase difference between the clock to be detected and the sampling clock in the current sampling period; and after the sampling ends, a final phase value of the clock to be detected is obtained according to initial phase values obtained in respective sampling periods.

An apparatus has a plurality of multi-level comparison circuits, each coupled to a pair of wires in a three-wire communication link, a plurality of first-level clock recovery circuits and a second-level clock recovery circuit. Each multi-level comparison circuit provides a multibit signal as an output. Each first-level clock recovery circuit includes a plurality of first-level flipflops clocked by transitions in a multibit signal received from one multi-level comparison circuit of the plurality of multi-level comparison circuits, and a first delay circuit that delays an output of the each first-level clock recovery circuit to provide a first reset signal that resets the each first-level clock recovery circuit. The second-level clock recovery circuit includes a second-level flipflop clocked by transitions in the outputs of the plurality of first-level clock recovery circuits, and a second delay circuit that delays an output of the second-level clock recovery circuit to provide a second reset signal to the second-level flipflop.

A communication apparatus includes a plurality of clocks configured to output signals indicating current times, a plurality of counter units configured to synchronize with the plurality of clocks using the signals indicating the current times output from the plurality of clocks, an instruction unit configured to give an instruction to acquire count values of the plurality of counter units, an acquisition unit configured to acquire the count values of the plurality of counter units based on the instruction from the instruction unit, and a calculation unit configured to calculate a difference between the acquired count values.

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.