CCSDS Proximity-1 Relay-Link Controller

What it is

ccsds_prox1 is a CCSDS Proximity-1 (CCSDS 211.0-B) space relay-link controller: the digital link layer for the short-range proximity hop between a deep-space orbiter and a surface asset (lander / rover), used once the orbiter becomes a store-and-forward relay for that asset.

Key Features

• Proximity-1 Transfer-Frame framing: ASM (0x352EF853) detect on RX / insert on TX, a 5-octet header (SCID, port-id, source-or-dest, COP-1 sequence, data-length), the data field, and a trailing CRC-16-CCITT, generated and checked by one shared byte-step function
• COP-P go-back-N sequence control (FARM/FOP): a FOP transmit counter stamps each TX frame; a FARM expected-sequence counter accepts an in-order frame (implicit ACK) and raises a retransmit request on a sequence mismatch
• Hailing -> data -> timing phase FSM with a bounded hailing (link-acquisition) watchdog; a stalled acquisition reports err_code 4 (link lost)
• Single APB4-lite aperture carries both config (CFG: SCID/port-id/sequence-window) and payload: byte-serial TX_DATA append plus a one-word-per-accepted-frame RX_DATA pop from a SECDED fifo_ecc buffer
• ASIL-B safety overlay: config-register even parity (err_code 1), RX-buffer SECDED double-bit (err_code 2), frame CRC/ASM/sequence integrity gate (err_code 3), hailing timeout (err_code 4), and complementary-DMR on the phase/COP-P FSMs plus sequence counters (err_code 9)
• Six fi_* DFT fault-inject inputs prove every mechanism one at a time (tie 0 in mission mode); the self-checking testbench runs a full TX/RX/COP-P functional loop plus one directed test per mechanism
• Measured ISO 26262 metrics: SPFM 92.46%, LFM 88.73%, PMHF 6.53×10⁻⁹/h — PASS against the ASIL-B target with margin on every metric

Standards & Compliance

CCSDS 211.0-B (Proximity-1 Space Link Protocol); ISO 26262 ASIL-B SEooC (SPFM 92.46%, LFM 88.73%, PMHF 6.53×10⁻⁹/h)

Functional Safety

ASIL-B (SEooC) · SPFM 92.46% · LFM 88.73% · PASS

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

Register Map

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

Getting Started

// Minimal instantiation
ccsds_prox1 #(
  .ADDR_W(6)
) u_ccsds_prox1 (
  .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.