:orphan:

Black Channel: Radio communication
==================================

.. blch:: Radio Communication
   :id: BLCH0001
   :tags: blch
   :date: 2025-06-06
   :status: PASS

Overview
========

Radio communication between Simplifier units are handled via a black channel.
The packets sent out contains both a CRC (which CPU1 calculates), and a secure Chaskey hash (which CPU2 calculates).
On the receving end, both CPUs checks the CRC and hash.
The black channel thus begins directly at the SPI output of CPU1 (which communicates with the radio chip), and ends at the SPI end
of CPU1 on the receiving node.


Tables
======

The black channel fulfills 61508-2 and 61784-3:2021, justified in this document, together with the RER calculations.

.. csv-table:: 61508-2:2010 7.4.11.1 requirements
   :file: blch0001_resources/61508_2_7_4_11.csv
   :widths: 25 25 15 25
   :header-rows: 1

.. csv-table:: 61784-3:2021 Annex D - Verification of safety measures
   :file: blch0001_resources/61784_3_annex_d.csv
   :widths: 25 25 15 25
   :header-rows: 1

.. csv-table:: 61784-3:2021 5.4 - Deterministic remedial measures
   :file: blch0001_resources/61784_3_5_4.csv
   :widths: 25 25 15 25
   :header-rows: 1

Residual Error Rate
-------------------
RER requirements are stated in 61784-3:2021, 5.8.5.
Reference the :download:`RER <../resources/FSD351 Residual Error Rate.ods>` for detailed calculation.
Radio communication is handled in sheet "2. SmallPacket".


Revision History
****************

.. list-table::
   :header-rows: 1

   * - Date
     - By
     - Version
     - Description

   * - 2025-08-01
     - Jesper Ribbe
     - V01
     - Initial version