Circuit apparatus and oscillator

An oscillator comprising:

• a resonator;
• an oscillation control circuit configured to control oscillation of the resonator;
• a counter circuit configured to count a number of pulses of an oscillation signal output from the oscillation control circuit;
• and
• an interface configured to communicate with an external device, wherein
• when a first signal that determines a measurement period is received from the external device, the counter circuit counts the number of pulses of the oscillation signal output during the measurement period, and
• the interface outputs a measurement result of the number of pulses corresponding to a frequency of the oscillation signal to the external device.

A circuit apparatus comprising:

• an oscillation control circuit configured to control oscillation of a resonator;
• a measurement unit configured to measure information corresponding to a frequency of an oscillation signal output from the oscillation control circuit;
• and
• an interface, wherein
• when a first signal that determines a measurement period is received from outside, the measurement unit measures the information corresponding to the frequency of the oscillation signal output during the measurement period,
• the interface outputs a measurement result of the information corresponding to the frequency,
• the circuit apparatus has a normal mode and a test mode,
• the measurement unit measures the information corresponding to the frequency when the test mode is instructed from the outside, and
• the interface receives the first signal after the circuit apparatus transitions to the test mode.