HotRIO Slave Sub-Block
======================

The HotRIO Slave Sub-Block is a communication-interface sub-block that provides the microcontroller with access to status, diagnostic, and configuration information for a HotRIO Slave connection on the board.

As described in the corresponding section, the position of this sub-block depends on the ordering of preceding blocks and on the size of the Hardware Interfaces block. Consequently, the base address of this sub-block is parameter-dependent. In this document, all register addresses are specified relative to an offset.

Sub-Block header
----------------

The sub-block starts with a constant (CONST) header containing:

* an 8-bit identifier for this sub-block type; and
* an 8-bit field indicating optional features available in this sub-block.

For this sub-block, no optional features are defined; therefore, the feature field is reserved. The sub-block ID is ``1``.

.. regtreedoc::
  :file: ./source/design/Architecture/CommunicationsSubBlocks/HotRIOSlaveSubBlock.json
  :register: ["Sub-block header"]
  :addressoverride: Offset + 0x0000

Status register
---------------

The HotRIO Slave Sub-Block provides a status register from which diagnostic indicators describing the current state of the HotRIO Slave can be read.

Any change in slave status observed through this register shall be signaled by asserting the **Communication-interface status flag** in the **Interrupt register**.

.. regtreedoc::
  :file: ./source/design/Architecture/CommunicationsSubBlocks/HotRIOSlaveSubBlock.json
  :register: ["HotRIO Slave status register"]
  :addressoverride: Offset + 0x0001

Diagnostics
-----------

The HotRIO Slave Sub-Block includes five diagnostic registers exposed by the HotRIO Slave module. These registers provide monitoring metrics for the microcontroller to supervise the HotRIO Slave communication interface.

.. regtreedoc::
  :file: ./source/design/Architecture/CommunicationsSubBlocks/HotRIOSlaveSubBlock.json
  :register: ["Packets received"]
  :addressoverride: Offset + 0x0002

.. regtreedoc::
  :file: ./source/design/Architecture/CommunicationsSubBlocks/HotRIOSlaveSubBlock.json
  :register: ["kchar error counter"]
  :addressoverride: Offset + 0x0003

.. regtreedoc::
  :file: ./source/design/Architecture/CommunicationsSubBlocks/HotRIOSlaveSubBlock.json
  :register: ["parity error counter"]
  :addressoverride: Offset + 0x0004

.. regtreedoc::
  :file: ./source/design/Architecture/CommunicationsSubBlocks/HotRIOSlaveSubBlock.json
  :register: ["CTC error"]
  :addressoverride: Offset + 0x0005

.. regtreedoc::
  :file: ./source/design/Architecture/CommunicationsSubBlocks/HotRIOSlaveSubBlock.json
  :register: ["CTC events"]
  :addressoverride: Offset + 0x0006