SpaceFibre Digital Link-Layer Controller

What it is

A configurable SpaceFibre (ECSS-E-ST-50-11C) digital link-layer controller delivered as synthesizable SystemVerilog soft-IP, with an APB4-lite register interface and a rad-tolerant / ASIL-B safety overlay (fault latch, config parity, link/retry-FSM DMR shadow, watchdog).

Key Features

• Full link control path in one core: frame layer (DATA/Broadcast/FCT/IDLE, CRC-16-CCITT) + per-VC credit flow control + QoS arbiter + retry layer over one APB4-lite slave
• FCT-based credit flow control: per-VC transmit FIFOs gated by far-end credit; an FCT grant exceeding CREDIT_LIMIT is a detected credit violation -> err_code 3 (saturated, not overrun)
• Deterministic priority + bandwidth-reserved QoS arbitration across virtual channels, sized per mission traffic model via VCn_QOS.PRIO/BW_RESERVED for mixed-criticality telemetry vs bulk-data VCs
• Sequence-numbered retry layer for link-integrity/availability: a CRC-16 or sequence error requests a retransmit from the failed sequence (RETRYCNT tracks retransmit/NACK trend) rather than dropping data
• Vendor-SerDes-ready boundary: sits on an already-decoded {word, K-flag} interface (tx_word/tx_kctrl, rx_word/rx_kctrl) — no on-chip 8b10b/64b66b coding, CDR, or lane alignment
• Split config/data planes: parity-protected APB4-lite QoS/credit/timeout config (err_code 1) carries no payload; the decoded-word ports carry the QoS-scheduled VC traffic exclusively
• ASIL-B safety overlay: config parity (err_code 1), CRC/FCT-credit/sequence protocol faults (err_code 3), link-establish/credit-stall watchdog (err_code 4), KEEP_ATTR link/retry-FSM DMR (err_code 9); catalog FMEDA SPFM 91.40%, LFM 90.36%, PMHF 5.21×10⁻⁹/h, PASS ASIL-B

Standards & Compliance

ECSS-E-ST-50-11C SpaceFibre; APB4-lite config slave; ISO 26262 ASIL-B SEooC (SPFM 91.40%, LFM 90.36%, PMHF 5.21×10⁻⁹/h)

Functional Safety

ASIL-B target (SEooC) · SPFM 91.40% · LFM 90.36% · Informational — not gated

Informational FMEDA — this IP is reported but NOT gated. The SPFM/LFM figures above are engineering estimates from a model that is not held to the ASIL metric gates (QM, safety-by-composition, a vendor-core overlay, or a pre-sign-off Technology Preview, depending on the IP). They are not a certification claim and must not be relied on as one. See the safety manual for this IP’s exact status, assumptions of use, and any open items.

ISO 26262-5 FMEDA method (transferable evidence for the ECSS-Q-ST-60 / radiation case) · FMEDA available · Safety Manual included

Register Map

…7 more registers — see datasheet for the full table.

Getting Started

// Minimal instantiation
spacefibre #(
 .ADDR_W(6)
) u_spacefibre (
 .clk (clk),
 .rst_n (rst_n),
 // APB4
 .p_paddr (paddr),
 .p_psel (psel),
 .p_penable (penable),
 .p_pwrite (pwrite),
 .p_pwdata (pwdata),
 .p_prdata (prdata),
 .p_pready (pready),
 // Safety
 .err_clear (1'b0),
 .err_valid (err_valid),
 .err_code (err_code)
);

Configure via the CTRL register after reset to enable the IP and set operating parameters. Monitor err_valid / err_code for any safety faults reported by the built-in safety monitor.