Edge FPGA Microsecond-Deterministic Actuation
Field-programmable gate arrays at the machine edge execute control logic in fixed clock cycles, giving cycle-exact, jitter-free actuation for both machines.
Why FPGAs at the edge
A general-purpose CPU running an operating system cannot promise when an instruction retires; caches, interrupts, and schedulers introduce variance. Kronos places the fastest control and all protection logic on FPGA fabric physically adjacent to the machine, where a computation compiled to gates executes in a known, fixed number of clock cycles every time.
Cycle-exact execution
At a fabric clock of, say, 200 MHz (5 ns/cycle), a pipeline of depth N completes in exactly N·5 ns regardless of input values. There is no instruction fetch, no branch misprediction, no cache miss. Latency equals pipeline depth times clock period, plus fixed I/O, which is why the 10 µs boundary is achievable with margin.
What runs in fabric
- Breeder: real-time equilibrium reconstruction feeding PF-coil current loops; vertical position control; disruption precursor thresholds.
- Burner: end-plug density loop, ambipolar potential estimator, DEC collector-grid modulation waveform synthesis.
- Both: quench precursor comparators, interlock voting, watchdog and heartbeat logic.
Fixed-point discipline
Fabric control math is implemented in fixed-point arithmetic with statically analyzed word growth, so numerical range and rounding are known at synthesis time. Where a gain matrix K multiplies a state vector x to form an actuation u = -Kx, the multiply-accumulate tree is fully unrolled and pipelined; the result is available every clock with deterministic quantization error bounded at design time.
Reprogrammability matters: the same board can host the breeder's shape controller or the burner's plug controller by loading a different bitstream. This lets Kronos share a hardened control-plane platform across both machines while keeping each loop specialized. Retraining and model updates happen offline at L0; the validated bitstream is the only thing that ever changes on the edge.