SpaceWire RMAP Target/Initiator Engine

What it is

spacewire_rmap is a SpaceWire RMAP (Remote Memory Access Protocol, ECSS-E-ST-50-52C) target and initiator engine: it lets one SpaceWire node read, write, or read-modify-write the memory or register space of another node without running software on the remote end.

Key Features

• RMAP target: full command-header decode (logical address / protocol-id / instruction / key / transaction-id / 32-bit address / 24-bit data-length / header-CRC), a req/gnt/rvalid memory bus tolerant of any read latency, and a status-coded reply (OK / key-error 0x03 / invalid-instruction 0x02 / header-CRC 0x07 / data-CRC 0x08) with read data + data-CRC
• RMAP initiator: assembles a read or write command with a correct header-CRC (and, for writes, data-CRC) from configured LADDR/KEY/MEMBASE, and parses the inbound reply’s status byte into INI_STAT
• One shared RMAP CRC-8 (polynomial 0xE7, ECSS-E-ST-50-52C) generate+check byte step accumulates the header-CRC and data-CRC identically on both the target and the initiator
• Authorize-then-execute: a destination-key mismatch, header-CRC or data-CRC fault, or invalid instruction rejects the command with an error reply before the memory bus is touched → err_code 3
• Bounded transaction-timeout watchdog on the memory-access phase (fixed at 2¹⁶−1 cycles) → err_code 4, catching a hung memory bridge or a reply that never completes
• Even-parity protection on the LADDR/KEY/MEMBASE/CTRL config registers → err_code 1; KEEP_ATTR complementary-DMR lockstep on both the command and reply FSMs → err_code 9, all into one safety_monitor with fi_par/fi_crc/fi_timeout/fi_dmr DFT-inject proof points
• v0.1 protocol subset (documented AoU, not silent): reply-address-field length 0 / flat addressing only, address always auto-increments (non-incrementing commands not honored), and verify-before-write (RMW compare) is a firmware obligation

Standards & Compliance

SpaceWire RMAP ECSS-E-ST-50-52C target + initiator (external SpaceWire link, ECSS-E-ST-50-12C, via the catalog spacewire codec); ISO 26262 ASIL-B SEooC (SPFM 91.40%, LFM 88.52%, PMHF 1.23×10⁻⁸/h)

Functional Safety

ASIL-B target (SEooC) · SPFM 91.40% · LFM 88.52% · 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

Getting Started

// Minimal instantiation
spacewire_rmap #(
 .ADDR_W(6)
) u_spacewire_rmap (
 .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.