Digital real time clock monitor for a GNSS receiver and single pin signalling for power-on reset and wake-up interrupt

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.

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.