System and method for calibrating capacitor-based oscillators in crystal-less devices

A method for calibrating an oscillator in an electronic device, the electronic device configured to communicate with an external device via an interface, the oscillator configurable to a plurality of coarse-tuned settings and a plurality of fine-tuned settings, each of the plurality of coarse-tuned settings and the plurality of fine-tuned settings resulting in a different frequency output by the oscillator, the method comprising:

• iteratively performing for the plurality of coarse-tuned settings:
• configuring the oscillator to a respective coarse-tuned setting;
• receiving a first signal indicative of a periodic signal from the electronic device via the interface;
• receiving a second signal indicative of the periodic signal from the electronic device via the interface;
• and
• determining a number of cycles output from the oscillator at the respective coarse-tuned setting in between when the first signal was received and the second signal was received;
• selecting one of the plurality of coarse-tuned settings to configure the oscillator based on the determined number of cycles output from the oscillator at the respective coarse-tuned settings;
• iteratively performing for the plurality of fine-tuned settings within the selected one of plurality of coarse-tuned capacitor settings:
• configuring the oscillator to a respective fine-tuned setting;
• receiving a third signal indicative of the periodic signal from the electronic device via the interface;
• receiving a fourth signal indicative of the periodic signal from the electronic device via the interface;
• and
• determining a number of cycles output from the oscillator at the respective fine-tuned setting in between when the third signal was received and the fourth signal was received;
• selecting one of the plurality of fine-tuned settings within the selected one of plurality of coarse-tuned capacitor to configure the oscillator based on the determined number of cycles output from the oscillator at the respective fine-tuned settings.