Systems and methods are provided for calibrating the internal oscillator of a microcontroller from a remote clock source. In some embodiments, an electronic device can request timing information from a third party device using a timing independent signal. The timing information received from the third party device may be used to calibrate the microcontroller clock of the electronic device. In some embodiments, the internal oscillator may be calibrated based on timing information received from multiple third party devices. Once calibrated, the microcontroller may initiate timing dependent communication with other electronic devices using a timing dependent protocol, such as a serial protocol.