Aitech’s S940 Digital I/O card design is based on a variety of discrete TTL, RS422 and opto-isolated. The S940 is designed with a PCI bridge implemented by an anti-fuse FPGA allowing a processor module like S950 to access the Digital I/Os from the cPCI bus.
The S940 provides 12 RS422 outputs and 4 RS422 inputs with state-machines implemented in the FPGA to operate the RS422 channels. The S940 interfaces with typical satellite guidance, navigation and control sensors such as Space Integrated GPS/INS (SIGI), torque rods, solar array drive electronics, separate switches, reaction wheels and payloads with UART interface. The control to these interfaces are
accomplished by memory-mapped software registers designed into the FPGA.
In addition to providing solar array drive electronics current drivers, the three H-bridge circuitry can also be used as motor controllers for other applications. All the RS422 channels can be regrouped and tailored to specific needs by means of modifying the VHDL implementation inside the FPGA.