Methods and circuitry for relatively low-speed bus time stamping and triggering for use in acoustic object and gesture detection and recognition are presented in this disclosure. A master device and slave devices can be interfaced via a communication link that includes a data line and a clock line. The master device generates and controls a clock signal on the clock line and sends a synchronization command over the data line to the slave devices. The master device receives timestamp and/or other information corresponding to events detected at each slave device, such as a detected acoustic wave reflected from an object. The master device tracks transitions and frequencies of the clock signal, and determines a time of the event based on the timestamp information, the tracked transitions and the frequencies. The master device can use the event times to derive positions and gestures associated with detected objects.