Radiation Bit-Flip Detector 2D: SEU & Memory Scrubbing

Radiation Environment

Cosmic-ray flux 4.0 hits/s

Scrub interval 6.0 s

Memory Status

SEU events

EDAC corrected

Pending (1-bit)

Uncorrectable

Word error rate

0.00%

Healthy word (0 bit errors) 1-bit error — correctable by EDAC 2+ bit errors — uncorrectable failure

How it works

Onboard memory is modeled as N independent words, each protected by a SECDED (single-error-correct, double-error-detect) Hamming-style code, laid out here as a flat 2D grid (25 columns × 20 rows) instead of the source simulator's 3D block. Cosmic-ray and trapped-proton strikes arrive as a Poisson process with rate λ (the flux slider, in expected hits/second):

P(k hits in Δt) = (λΔt)^k · e^(−λΔt) / k!

Each hit flips one random bit in one random word:

0 → 1 bit error: silently correctable — the syndrome uniquely identifies the flipped bit.
1 → 2 bit errors: the code can only detect, not correct — the word becomes an uncorrectable failure until the whole word is rewritten.

A periodic memory scrub (the scrub-interval slider) sweeps the address space column by column every few seconds, reading each word and rewriting any word sitting at exactly one bit error back to its correct value — before a second hit can turn it into an unrecoverable double-bit error. This is standard practice in radiation-hardened flight computers (e.g. ECC DRAM scrubbing on deep-space and LEO avionics).

Toggle EDAC off to see the counterfactual: without scrubbing, single-bit errors sit unfixed and flux alone determines how fast the array degrades into red, uncorrectable words — the same trade-off real FDIR designers tune against detection thresholds and false-alarm rates.

Drag to pan the array, scroll/pinch to zoom in on individual words.

flux: 4.0 hits/s EDAC: on · scrub every 6.0s next scrub: 6.0s

drag to pan · scroll to zoom