Methods and apparatus for synchronizing data transfers across clock domains for using heads-up indications. An integrated circuit includes a first-in first-out buffer (FIFO); a memory controller configured to operate in a first clock domain and coupled to the FIFO, the first clock domain associated with a first clock signal; a data fabric configured to operate in a second clock domain and coupled to the FIFO, the second clock domain associated with a second clock signal, a second frequency of the second clock signal being different from a first frequency of the first clock signal; and a controller coupled to the FIFO. In some instances, the controller determines a phase relationship between the first clock signal and the second clock signal; monitors one or more first clock edges of the first clock signal and one or more second clock edges of the second clock signal; and sends a first heads-up signal to the memory controller.

Methods and apparatus employ an asynchronous first-in-first-out buffer (FIFO), that includes a plurality of entries. Control logic determines a timing separation between a write header valid signal and corresponding write data valid signal for a write operation to an entry in the first-in-first-out buffer (FIFO) and performs a read of the corresponding data from the entry in the FIFO in the second clock domain, based on the determined timing separation of the write header valid signal and corresponding write data valid signal, and based on a clock frequency ratio between the first and second clock domains.

A method and apparatus for synchronizing a timebase is disclosed. A timebase management circuit includes limit circuitry, in a first clock domain, which generates, based on a global timebase, an initial timebase limit. The timebase management circuit includes, in a second clock domain, adjustment circuitry that generates an adjusted timebase limit based on the initial timebase limit. A storage circuit in the second clock domain stores a local timebase. Update circuitry, coupled to an output of the storage circuit, generates an updated local timebase using a clock signal in the second clock domain, wherein the updated local timebase is subject to the adjusted timebase limit.

A method and apparatus for synchronizing a timebase is disclosed. A timebase management circuit includes limit circuitry, in a first clock domain, which generates, based on a global timebase, an initial timebase limit. The timebase management circuit includes, in a second clock domain, adjustment circuitry that generates an adjusted timebase limit based on the initial timebase limit. A storage circuit in the second clock domain stores a local timebase. Update circuitry, coupled to an output of the storage circuit, generates an updated local timebase using a clock signal in the second clock domain, wherein the updated local timebase is subject to the adjusted timebase limit.

A calibration controller of a receiving chip learns a difference between a first clock phase of an input clock for controlling inputs on a data path to a buffer of the receiving chip at a clock boundary and a second clock phase of a chip clock for controlling outputs from the buffer on the data path at the clock boundary. The calibration controller dynamically adjusts a phase of a reference clock driving a phase locked loop that outputs the chip clock to adjust the second clock phase of the chip clock with respect to the first clock phase to minimize a latency on the data path at the clock boundary to a half a cycle granularity.

Methods and apparatus for synchronizing data transfers across clock domains for using heads-up indications. An integrated circuit includes a first-in first-out buffer (FIFO); a memory controller configured to operate in a first clock domain and coupled to the FIFO, the first clock domain associated with a first clock signal; a data fabric configured to operate in a second clock domain and coupled to the FIFO, the second clock domain associated with a second clock signal, a second frequency of the second clock signal being different from a first frequency of the first clock signal; and a controller coupled to the FIFO. In some instances, the controller determines a phase relationship between the first clock signal and the second clock signal; monitors one or more first clock edges of the first clock signal and one or more second clock edges of the second clock signal; and sends a first heads-up signal to the memory controller.

A calibration controller of a receiving chip learns a difference between a first clock phase of an input clock for controlling inputs on a data path to a buffer of the receiving chip at a clock boundary and a second clock phase of a chip clock for controlling outputs from the buffer on the data path at the clock boundary. The calibration controller dynamically adjusts a phase of a reference clock driving a phase locked loop that outputs the chip clock to adjust the second clock phase of the chip clock with respect to the first clock phase to minimize a latency on the data path at the clock boundary to a half a cycle granularity.

A system and method to mitigate or complicate the use of differential power analysis (DPA) and simple power analysis (SPA) in the attack of a targeted integrated circuit, or device containing an integrated circuit, that is processing sensitive information. The system and method modifies the regularity of a clock that initiates the power events within the circuit such that subsequent processing of information does not always occur at the same time.

An arrangement for transferring a data signal (data_a) from a first clock domain (2) to a second clock domain (4) in a digital system. The arrangement has a signal input (6, 7) for receiving an input signal (data_a) from the first clock domain (2), means (6, 7) for storing the input signal (data_a), and means (12, 13) for transferring the input signal (data_a) to the second clock domain (4) following a transition in the clock signal (ck) of the second clock domain (4).

A method and apparatus for synchronizing a timebase is disclosed. A timebase management circuit includes limit circuitry, in a first clock domain, which generates, based on a global timebase, an initial timebase limit. The timebase management circuit includes, in a second clock domain, adjustment circuitry that generates an adjusted timebase limit based on the initial timebase limit. A storage circuit in the second clock domain stores a local timebase. Update circuitry, coupled to an output of the storage circuit, generates an updated local timebase using a clock signal in the second clock domain, wherein the updated local timebase is subject to the adjusted timebase limit.