Monitoring spacecraft health is a critical function. To reliably perform a health and safety checkout, hundreds of sensors are deployed in order to measure voltages, temperatures, pressures, etc.
In the past, sensor data were typically collected with data-acquisition systems based on space-qualified discrete AC/DC components, multiplexers, voltage references, signal conditioning circuits, memory units, and input/output interface units. However, this approach requires a lot of mass, size, power dissipation, and wiring complexity. Although integrated data acquisition chips are already used in commercial applications, these devices cannot easily be used in space applications because of space qualification requirements. To fill this need in space applications, the remote input/output (RIO)/temperature RIO (TRIO) chip effort was started at APL and NASA/JPL, resulting in the TRIO smart sensor data-acquisition system on a chip that is now used in several space missions, including MESSENGER, New Horizons, and STEREO, as well as in the JPL/X2000 system bus architecture.
Results are stored in internal memory and are available to the user via a parallel or a serial (inter-integrated circuit) bus. The implemented I2C protocol is enhanced with a protection circuit that makes communication with other devices reliable and robust.