Abstract: In described examples, a first clock generator generates an output clock signal in response to an input reference signal and in response to a feedback signal that is generated in response to the output clock signal. A code generator generates a code in response to the input reference signal. A loss detector generates an indication of a loss of the input reference signal in response to the feedback signal and at least two codes generated by the code generator.

Abstract: Lockstep comparators and related methods are described. An example apparatus includes self-test logic circuitry having first outputs, and comparator logic including selection logic having first inputs and second outputs, ones of the first inputs coupled to the first outputs, first detection logic having second inputs and third outputs, the second inputs coupled to the second outputs, second detection logic having third inputs and fourth outputs, the third inputs coupled to the third outputs, latch logic having fifth inputs and fifth outputs, the third output and the fourth output coupled to the fifth inputs, and error detection logic having sixth inputs coupled to the fifth inputs.

Abstract: A phase-locked loop (PLL) includes a phase-frequency detector (PFD) having a first PFD input, a second PFD input, and a PFD output. The PFD is configured to generate a first signal on the PFD output. The first signal comprises pulses having pulse widths indicative of a phase difference between signals on the first and second PFD inputs. A low pass filter (LPF) has an LPF input and an LPF output. The LPF input is coupled to the PFD output. A flip-flop has a clock input and a flip-flop output. The clock input is coupled to the LPF output. A lock-slip control circuit is coupled to the flip-flop output and to the first PFD input. The lock-slip control circuit is configured to determine phase-lock and phase-slip based at least in part on a signal on the flip-flop output.

Abstract: Lockstep comparators and related methods are described. An example apparatus includes self-test logic circuitry having first outputs, and comparator logic including selection logic having first inputs and second outputs, ones of the first inputs coupled to the first outputs, first detection logic having second inputs and third outputs, the second inputs coupled to the second outputs, second detection logic having third inputs and fourth outputs, the third inputs coupled to the third outputs, latch logic having fifth inputs and fifth outputs, the third output and the fourth output coupled to the fifth inputs, and error detection logic having sixth inputs coupled to the fifth inputs.

Abstract: A phase-locked loop (PLL) includes a phase-frequency detector (PFD) having a first PFD input, a second PFD input, and a PFD output. The PFD is configured to generate a first signal on the PFD output. The first signal comprises pulses having pulse widths indicative of a phase difference between signals on the first and second PFD inputs. A low pass filter (LPF) has an LPF input and an LPF output. The LPF input is coupled to the PFD output. A flip-flop has a clock input and a flip-flop output. The clock input is coupled to the LPF output. A lock-slip control circuit is coupled to the flip-flop output and to the first PFD input. The lock-slip control circuit is configured to determine phase-lock and phase-slip based at least in part on a signal on the flip-flop output.

Abstract: A system, method and computer readable medium for operating a First In, First Out (FIFO) buffer that transfers data between a host and a plurality of endpoints using chip select is disclosed. The method includes receiving a current value of a read pointer and a status for an active endpoint and reading data at a location to which the read pointer points and setting a tag associated with the location to which the read pointer points to indicate availability.

Abstract: Lockstep comparators and related methods are described. An example apparatus includes self-test logic circuitry having first outputs, and comparator logic including selection logic having first inputs and second outputs, ones of the first inputs coupled to the first outputs, first detection logic having second inputs and third outputs, the second inputs coupled to the second outputs, second detection logic having third inputs and fourth outputs, the third inputs coupled to the third outputs, latch logic having fifth inputs and fifth outputs, the third output and the fourth output coupled to the fifth inputs, and error detection logic having sixth inputs coupled to the fifth inputs.

Abstract: In described examples, a counter system includes a counter, a parity detector, a toggle flop, and a comparator. The counter iterates a count through a set of binary states in response to a clock signal, so that a binary value of a single bit of the count changes at each iteration. The parity detector detects the parity of the count. The toggle flop output is coupled to the toggle flop input. The toggle flop outputs a binary flop value. The binary flop value toggles between zero and one in response to the toggle flop input and the clock signal. The comparator compares the parity of the count and the toggle flop output, and outputs a first comparator value if the parity of the count and the toggle flop output are the same, and a second comparator value if the parity of the count and the toggle flop output are different.

Abstract: In described examples, a counter system includes a counter, a parity detector, a toggle flop, and a comparator. The counter iterates a count through a set of binary states in response to a clock signal, so that a binary value of a single bit of the count changes at each iteration. The parity detector detects the parity of the count. The toggle flop output is coupled to the toggle flop input. The toggle flop outputs a binary flop value. The binary flop value toggles between zero and one in response to the toggle flop input and the clock signal. The comparator compares the parity of the count and the toggle flop output, and outputs a first comparator value if the parity of the count and the toggle flop output are the same, and a second comparator value if the parity of the count and the toggle flop output are different.

Abstract: In described examples, a first clock generator generates an output clock signal in response to an input reference signal and in response to a feedback signal that is generated in response to the output clock signal. A code generator generates a code in response to the input reference signal. A loss detector generates an indication of a loss of the input reference signal in response to the feedback signal and at least two codes generated by the code generator.

Abstract: In described examples, a first clock generator generates an output clock signal in response to an input reference signal and in response to a feedback signal that is generated in response to the output clock signal. A code generator generates a code in response to the input reference signal. A loss detector generates an indication of a loss of the input reference signal in response to the feedback signal and at least two codes generated by the code generator.

Abstract: A phase-locked loop (PLL) includes a phase-frequency detector (PFD) having a first PFD input, a second PFD input, and a PFD output. The PFD is configured to generate a first signal on the PFD output. The first signal comprises pulses having pulse widths indicative of a phase difference between signals on the first and second PFD inputs. A low pass filter (LPF) has an LPF input and an LPF output. The LPF input is coupled to the PFD output. A flip-flop has a clock input and a flip-flop output. The clock input is coupled to the LPF output. A lock-slip control circuit is coupled to the flip-flop output and to the first PFD input. The lock-slip control circuit is configured to determine phase-lock and phase-slip based at least in part on a signal on the flip-flop output.

Abstract: A phase-locked loop (PLL) includes a phase-frequency detector (PFD) having a first PFD input, a second PFD input, and a PFD output. The PFD is configured to generate a first signal on the PFD output. The first signal comprises pulses having pulse widths indicative of a phase difference between signals on the first and second PFD inputs. A low pass filter (LPF) has an LPF input and an LPF output. The LPF input is coupled to the PFD output. A flip-flop has a clock input and a flip-flop output. The clock input is coupled to the LPF output. A lock-slip control circuit is coupled to the flip-flop output and to the first PFD input. The lock-slip control circuit is configured to determine phase-lock and phase-slip based at least in part on a signal on the flip-flop output.

Abstract: A system, method and computer readable medium for operating a First In, First Out (FIFO) buffer that transfers data between a host and a plurality of endpoints using chip select is disclosed. The method includes receiving a current value of a read pointer and a status for an active endpoint and reading data at a location to which the read pointer points and setting a tag associated with the location to which the read pointer points to indicate availability.

Abstract: A phase-locked loop (PLL) includes a phase-frequency detector (PFD) having a first PFD input, a second PFD input, and a PFD output. The PFD is configured to generate a first signal on the PFD output. The first signal comprises pulses having pulse widths indicative of a phase difference between signals on the first and second PFD inputs. A low pass filter (LPF) has an LPF input and an LPF output. The LPF input is coupled to the PFD output. A flip-flop has a clock input and a flip-flop output. The clock input is coupled to the LPF output. A lock-slip control circuit is coupled to the flip-flop output and to the first PFD input. The lock-slip control circuit is configured to determine phase-lock and phase-slip based at least in part on a signal on the flip-flop output.

Abstract: In described examples, a first clock generator generates an output clock signal in response to an input reference signal and in response to a feedback signal that is generated in response to the output clock signal. A code generator generates a code in response to the input reference signal. A loss detector generates an indication of a loss of the input reference signal in response to the feedback signal and at least two codes generated by the code generator.

Abstract: A system, method and computer readable medium for operating a First In, First Out (FIFO) buffer that transfers data between a host and a plurality of endpoints using chip select is disclosed. The method includes receiving a current value of a read pointer and a status for an active endpoint and reading data at a location to which the read pointer points and setting a tag associated with the location to which the read pointer points to indicate availability.

Abstract: In described examples, a first clock generator generates an output clock signal in response to an input reference signal and in response to a feedback signal that is generated in response to the output clock signal. A code generator generates a code in response to the input reference signal. A loss detector generates an indication of a loss of the input reference signal in response to the feedback signal and at least two codes generated by the code generator.

Abstract: In described examples, a first clock generator generates an output clock signal in response to an input reference signal and in response to a feedback signal that is generated in response to the output clock signal. A code generator generates a code in response to the input reference signal. A loss detector generates an indication of a loss of the input reference signal in response to the feedback signal and at least two codes generated by the code generator.

Abstract: A system, method and computer readable medium for operating a First In, First Out (FIFO) buffer that transfers data between a host and a plurality of endpoints using chip select is disclosed. The method includes receiving a current value of a read pointer and a status for an active endpoint and reading data at a location to which the read pointer points and setting a tag associated with the location to which the read pointer points to indicate availability.