# US 10,502,838 B2 · Digital real time clock monitor for a GNSS receiver and single pin signalling for power-on reset and wake-up interrupt > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,838 B2 - Document ID: US10502838B2 - Status: Granted - Kind: B2 - Application number: 15/591,510 - Filed: 2017-05-10 - Published: 2017-08-24 - Granted: 2019-12-10 - Earliest claimed: 2013-10-09 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., Ltd. - Inventors: Daniel Babitch; Steven A Gronemeyer; Nicolas Vantalon - Web page: https://patentgrep.com/patent/US10502838B2 ## CPC - G01S 19/23: Testing, monitoring, correcting or calibrating of receiver elements - G01S 19/235: {Calibration of receiver components} - G01S 19/34: Power consumption - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract Methods, systems, and devices for monitoring a Real Time Clock (RTC) oscillator using Digital Signal Processing (DSP), where a resistance/capacitance (RC) oscillator is configured to output a digital pulse signal and a digital RTC Monitor Integrated Circuit (IC) is configured to monitor the RTC oscillator timing signal using the RC oscillator signal. In one aspect, the RTC Monitor IC includes an RTC input configured to receive the RTC oscillator timing signal; an RC input configured to receive the RC oscillator digital pulse signal; and an RTC reset output configured to output an RTC reset signal when a comparison of the RTC and RC oscillator inputs show the RTC oscillator has missed one or more clock cycles. A single wire input/output for both reset and interrupt signals between circuits is also described. ## Claims ### Claim 1 A portable electronic device having a Global Navigation Satellite System (GNSS) receiver, comprising: a Real Time Clock (RTC) oscillator which outputs an RTC timing signal; a digital Integrated Circuit (IC) monitor which outputs a reset signal when monitoring indicates that the RTC oscillator has missed at least one clock cycle; and a GNSS oscillator which outputs a GNSS timing signal and which, when re-starting GNSS operations after the GNSS oscillator has been powered down, does not use the RTC timing signal to re-correlate GNSS operations when the reset signal has been asserted by the digital IC monitor. ### Claim 2 (depends on 1) The portable electronic device of claim 1, further comprising: a resistance/capacitance (RC) oscillator which outputs an RC digital pulse signal, wherein the digital IC monitor uses the RTC timing signal and the RC digital pulse signal as input for monitoring whether the RTC oscillator has missed at least one clock cycle or has become otherwise dysfunctional. ### Claim 3 (depends on 2) The portable electronic device of claim 2, wherein the digital IC monitor outputs the reset signal when a comparison of the RTC timing signal and RC digital pulse signal shows that the RTC oscillator has missed at least one clock cycle. ### Claim 4 (depends on 3) The portable electronic device of claim 3, wherein the digital IC monitor is configured to divide a frequency of the RTC timing signal before processing and comparing the RC digital pulse with the RTC input by the digital IC monitor. ### Claim 5 (depends on 1) The portable electronic device of claim 1, wherein the digital IC monitor comprises one or more flipflops, digital logic gates, counters, and multiplexors. ### Claim 6 (depends on 1) The portable electronic device of claim 1, wherein the digital IC monitor comprises: a latch which, when it receives the reset signal, asserts and maintains a monitor signal, wherein, when re-starting GNSS operations after the GNSS oscillator has been powered down, the monitor signal indicates if the reset signal was asserted during a period when the GNSS oscillator has been powered-down. ### Claim 7 (depends on 6) The portable electronic device of claim 6, wherein the latch de-asserts the monitor signal when a monitor reset signal is received, and wherein the monitor reset signal is asserted after GNSS operations are re-started and re-correlated. ### Claim 8 (depends on 1) The portable electronic device of claim 1, wherein the digital IC monitor receives a Power-On/Reset (POR) signal when the portable electronic device is reset or powered on. ### Claim 9 (depends on 1) The portable electronic device of claim 1, wherein the RTC oscillator consumes less power than the GNSS oscillator and maintains timing while the GNSS oscillator is powered down. ### Claim 10 (depends on 1) The portable electronic device of claim 1, wherein the digital IC monitor also outputs a reset signal when monitoring indicates that the RTC oscillator malfunctions in a way other than missing at least one clock cycle. ### Claim 11 An electronic apparatus, comprising: a first circuit capable of generating any of a power-on signal, a reset signal, and a wake-up interrupt signal, wherein each of the power-on signal, the reset signal, and the wake-up interrupt signal is distinguishable by a number of clock cycles each of the power-on signal, the reset signal, and the wake-up interrupt signal is asserted; a single line operable to carry any of the power-on signal, the reset signal, and the wake-up interrupt signal from the first circuit to a second circuit; and the second circuit capable of receiving any of the power-on signal, the reset signal, and the wake-up interrupt signal over the single line from the first circuit, wherein the second circuit determines whether a received signal is the power-on signal, the reset signal, or the wake-up interrupt signal by detecting the number of clock cycles of the power-on signal, the reset signal, or the wake-up interrupt signal the received signal has asserted. ### Claim 12 (depends on 11) The electronic apparatus of claim 11, wherein a maximum possible clock frequency difference caused by frequency errors of both a clock of the first circuit and a clock of the second circuit are such that clock signal pulse widths are uniquely distinguishable at both ends of the single line. ### Claim 13 (depends on 11) The electronic apparatus of claim 11, wherein the single line comprises a bus, and wherein there are a plurality of second circuits each capable of receiving any of the power-on signal, the reset signal, and the wake-up interrupt signal transmitted by the first circuit. ### Claim 14 (depends on 11) The electronic apparatus of claim 11, wherein the single line is operable to carry signals bidirectionally, and wherein the second circuit is capable of generating and transmitting any of the power-on signal, the reset signal, and the wake-up interrupt signal over the single line to the first circuit. ### Claim 15 A method of monitoring a Real Time Clock (RTC) timing signal by a portable electronic device having a Global Navigation Satellite System (GNSS) receiver, comprising: outputting, by an RTC oscillator, the RTC timing signal; if monitoring indicates that the RTC oscillator has missed at least one clock cycle, outputting, by a digital Integrated Circuit (IC) monitor, a reset signal; and if the reset signal has been output by the digital IC monitor, not using, by a GNSS oscillator, the RTC timing signal to re-correlate GNSS operations when re-starting GNSS operations after the GNSS oscillator has been powered down. ### Claim 16 (depends on 15) The method of claim 15, further comprising: outputting, by a resistance/capacitance (RC) oscillator, an RC digital pulse signal, monitoring, by the digital IC monitor, whether the RTC oscillator has missed at least one clock cycle using the RTC timing signal and the RC digital pulse signal. ### Claim 17 (depends on 16) The method of claim 16, wherein the digital IC monitor outputs the reset signal when a comparison of the RTC timing signal and RC digital pulse signal shows that the RTC oscillator has missed at least one clock cycle. ### Claim 18 (depends on 17) The method of claim 17, further comprising: dividing a frequency of the RTC timing signal before processing and comparing the RC digital pulse signal with the RTC input. ### Claim 19 (depends on 15) The method of claim 15, wherein the digital IC monitor comprises one or more flipflops, digital logic gates, counters, and multiplexors. ### Claim 20 (depends on 15) The method of claim 15, further comprising: asserting, by the digital IC monitor when it receives the reset signal, and maintaining a monitor signal and determining, when re-starting GNSS operations after the GNSS oscillator has been powered down, if the reset signal was asserted during a period when the GNSS oscillator has been powered-down using the monitor signal. ### Claim 21 (depends on 20) The method of claim 20, further comprising: after GNSS operations are re-started and re-correlated, asserting a monitor reset signal; and de-asserting the monitor signal when the monitor reset signal is asserted. ### Claim 22 (depends on 15) The method of claim 15, further comprising: receiving, by the digital IC monitor, a Power-On/Reset (POR) signal when the portable electronic device is reset or powered on. ### Claim 23 (depends on 15) The method of claim 15, wherein the RTC oscillator is a lower power oscillator and the GNSS oscillator is a higher power oscillator, further comprising: maintaining, by the RTC oscillator, timing while the GNSS oscillator is powered down. ### Claim 24 (depends on 15) The method of claim 15, further comprising: if monitoring indicates that the RTC oscillator has become dysfunctional in a manner other than missing at least one clock cycle, outputting, by the digital Integrated Circuit (IC) monitor, the reset signal.