The Reaction Wheel Controller (RWC) is a space flight heritage PIM that converts signals between the wheel drivers and the control processor (IAU). The IAU sends torque commands to the drivers and receives status information such as wheel direction and speed. Commands and responses occur over RS422 busses. The status data is returned in response for each torque command received (ping pong).
The RWC has resources to control 4 individual wheels (4 channels). In addition to generating torque control and wheel speed indication, other status signals can be passed through the RWC from the wheel drivers. These statuses include motor current, driver temperature, and DC/DC converter status.
The RWC contains a FPGA with all the required digital logic functions. These include the UART for command and response formatting, parsing logic for torque command verification, PWM circuits for the DAC functions, and accumulators for combining the wheel speeds and directions into digital data. Through our deep experience in FPGA design, we provide sophisticated smarts in a single device and add built-in space environment performance and reliability improvement mechanisms.