System, Safety & Compute

APB 2-of-3 TMR Voter

APB4 bitwise 2-of-3 majority (TMR) voter with per-channel diagnostics and an ASIL-B safety monitor.

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ASIL-B

target

92.25%

SPFM

90.00%

LFM

PASS

FMEDA

1.3K

gates

1.0.0

version

The deliverable

What you’re licensing

APB4 bitwise 2-of-3 majority (TMR) voter with per-channel diagnostics and an ASIL-B safety monitor. It is delivered as a licensable soft-IP block engineered as an ASIL-B Safety Element out of Context — not just RTL, but the complete functional-safety work package needed to carry it into an ISO 26262 program:

Synthesizable RTL

Portable, vendor-neutral SystemVerilog that drops onto your existing SoC fabric — no foundry or EDA-tool lock-in.

Per-IP FMEDA report

SPFM / LFM / PMHF computed against the ASIL target per ISO 26262-5 — the quantitative analysis your assessor asks for.

Safety manual

Assumptions of use, the safety mechanisms and their diagnostic coverage — written to drop straight into your safety case.

IP-XACT + integration docs

A machine-readable descriptor plus register and integration documentation for fast, low-risk bring-up.

Self-checking testbench

A self-checking (crypto: bit-exact) testbench and a one-command build, so you can reproduce every claim on day one.

What it is

APB4 bitwise 2-of-3 majority (TMR) voter with per-channel diagnostics and an ASIL-B safety monitor. Three redundant W-bit input buses (vin_a/b/c) are bitwise-majority-voted to vout, so a single faulty channel is masked (outvoted) and the output stays correct — the system keeps running instead of dropping to a safe state.

Key Features

Bitwise 2-of-3 majority on three W-bit channels; single-channel fault masked, output stays correct
Dedicated parallel input buses (not a shared fabric) — no common-cause SPOF in data delivery
Live disagree reporting (err_code 9): masked-but-present fault / spent redundancy margin never silent
Per-channel sticky flags + saturating disagree-event counters to spot a degrading channel
≥2-channel disagree → latched vfault structural safe-state
Diverse voter self-check: majority recomputed a second way and compared (err_code 9)
Config-register parity (err_code 1); APB4 slave, 9-register diagnostic map

Standards & Compliance

IEC 61508 / ISO 26262 (incl. Part 9 dependent-failure analysis) — TMR redundancy architecture

Functional Safety

ASIL-B (SEooC) · SPFM 92.25% · LFM 90.00% · PASS

ISO 26262:2018 · FMEDA available · Safety Manual included

Register Map

Offset	Register	Description
`0x00`	CTRL	[0]=EN (enable disagree reporting / latching / counting; vout always votes)
`0x04`	STATUS	RO [0]=ANY (sticky) [1]=MULTI (sticky = vfault) [2]=DA [3]=DB [4]=DC (sticky)
`0x08`	VOUT	RO voted output word (diagnostic readback)
`0x0C`	CNTA	RO channel-A disagree-event count (saturating) 0x10 CNTB 0x14 CNTC
`0x18`	CLR	W1: clear sticky status + counters + latched vfault (only when no live disagree)

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

Getting Started

// Minimal instantiation
voter #(
  .ADDR_W(6)
) u_voter (
  .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.

Applications

Where it fits

Typically deployed in the safety backbone of an ASIL SoC — error detection, redundancy, and the fault-reaction path that takes the system to a safe state.

The case

Why license it, not build it

Skip 12–18 months

The FMEDA and the safety case are already generated. You integrate a finished safety element — you don’t stand up a safety-IP program to originate one.

One vendor, one safety story

Every block in the catalog shares the same safety architecture, fault-reaction model, and FMEDA methodology — so subsystems roll up cleanly.

Verified, not vapor

The RTL builds and passes today; the safety metrics come from analysis and fault injection against real RTL, not a datasheet promise.

Interested in APB 2-of-3 TMR Voter?

Pricing, the per-IP FMEDA, safety manual, and RTL data room are shared under a mutual NDA.

Talk to us →See related IP

Figures are pre-silicon engineering-grade estimates for a Safety Element out of Context (SEooC); final ASIL sign-off is the integrator’s, supported under NDA. FMEDA and Safety Manual available under NDA.

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