Solution
Serial Synchronous Interface (SSI) is a widely used serial interface between an absolute position sensor and a controller. SSI uses a clock pulse train from a controller to initiate a gated output from the sensor.
Position data is continually updated by the sensor and made available to the shift register. Between each clock pulse train there is a minimum dwell of 25 microseconds during which fresh data is moved into the register. Data is shifted out when the sensor receives a pulse train from the controller. When the
least significant bit (
LSB) goes HIGH and the minimum dwell time has elapsed, new data is available to read. Refer to the diagrams below for examples of a typical SSI block diagram, timing diagram, and a timing diagram showing the 25 microsecond dwell between data sets.
SSI Block Diagram
SSI Timing Diagram
SSI Timing for Sequential Measurements