micheleandClaude Sonnet 5
0e73eb4726
Was a separate, untracked directory (DataSheet/) outside the repo. Renamed to lowercase and moved in as hardware/v2/docs/datasheet/, with its own .gitignore for LaTeX build byproducts (compiled PDFs stay tracked, .aux/.log/.toc/etc do not). Now versioned and shares this repo's own remote instead of living untracked on disk. Content: IT+EN LaTeX chapter sources, reference manufacturer PDFs, and compiled datasheet PDFs including the 2026-09-07 SDRAM upgrade addendum (AS4C32M16SB-7BIN part/pinout/timing) in the v2-en chapters. Note: hardware/v2/docs/DatasheetLatex/ (and the v1 sibling) is a separate, already-tracked, differently-structured LaTeX document that predates this move -- left untouched, not merged, since its chapter set and content differ and merging was not requested. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
66 lines
3.4 KiB
TeX
66 lines
3.4 KiB
TeX
\chapter{Host / graph-loader interface}
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\label{ch:host}
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\begin{fnwarn}[Scope of this chapter]
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V1's own host interface is a real, placed, physically-verified SPI Mode~0
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slave (ch.~7 of the V1 datasheet). V2's equivalent --- a node-registration
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bus into \code{neural\_multiprocessor.v} --- has, in this revision, been
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exercised exclusively from Verilator testbenches and unconstrained
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synthesis top-levels. This chapter describes the \textbf{logical}
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protocol only; no real host-side driver (SPI or otherwise) has been
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built or placed yet. See ch.~\ref{ch:roadmap}.
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\end{fnwarn}
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\section{Node registration protocol}
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A simple valid/ready producer interface, backpressure-safe: the loader
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holds \code{reg\_valid} and the node's own fields until \code{reg\_ready}
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is observed high on the same cycle, exactly like registering into any
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FIFO. \code{reg\_ready} for a given \code{reg\_node\_id} is asserted
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whenever that node's own table slot is \code{EMPTY} (\S\ref{ch:sched}).
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\begin{tabularx}{\textwidth}{L{3.2cm} C{1.6cm} Y}
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\toprule
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\rowh \thd{Field} & \thd{Width} & \thd{Meaning} \\
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\midrule
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\code{reg\_node\_id} & $\lceil\log_2\text{N\_NODES}\rceil$ & This node's own id --- doubles as its table slot index. \\
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\rowa \code{reg\_required} & $\lceil\log_2(\text{MAX\_DEPS}{+}1)\rceil$ & How many of \code{reg\_producer\_ids} are meaningful (0 $\Rightarrow$ immediately \code{READY}). \\
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\code{reg\_producer\_ids} & \code{MAX\_DEPS}$\times\lceil\log_2\text{N\_NODES}\rceil$ & Packed array of producer node ids this node depends on. \\
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\rowa \code{reg\_x\_base} & \code{ADDR\_WIDTH} & Base byte address of this node's activation vector. \\
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\code{reg\_w\_base} & \code{ADDR\_WIDTH} & Base byte address of this node's weight vector. \\
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\rowa \code{reg\_n\_tiles} & 16 & Number of P\_IN-wide tiles to accumulate. \\
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\code{reg\_result\_addr} & \code{ADDR\_WIDTH} & Byte address the computed INT8 result is written to. \\
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\bottomrule
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\end{tabularx}
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\begin{fnnote}[A node id is a real, finite resource]
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Because dispatched node table slots are never reclaimed
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(\S\ref{ch:sched}), a loader driving many independent jobs over a long
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session must use a fresh \code{reg\_node\_id} for each one, within
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\code{N\_NODES}. Reusing a value before the system has been reset will
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simply be refused (\code{reg\_ready} stays low for an occupied,
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non-\code{EMPTY} node id) --- it will not corrupt anything, but it will
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also not register.
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\end{fnnote}
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\section{Result readback}
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The computed INT8 result is written to \code{reg\_result\_addr} through
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the same real PSRAM chain every other memory access uses --- there is no
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separate result-readback port; the host/loader reads the result byte
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back from PSRAM directly, the same convention every V2 testbench in this
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project uses for verification.
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\section{What a real host driver would still need to add}
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\begin{itemize}
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\item A physical transport (SPI, parallel bus, or otherwise) carrying
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the fields of \S\ref{ch:host}'s own table across a real pin
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interface --- not designed in this revision.
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\item A completion-notification path back to the host (V1's own
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\code{data\_ready\_n}/\code{STATUS.done} has no V2 analogue yet);
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today, completion is only observable internally
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(\code{dir\_job\_out\_done}) or by polling the expected result
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address.
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\item Per-job \code{bias}/\code{activation} selection, currently
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hardcoded to \code{bias=0}/\code{ACT\_RELU} for every job
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(\S\ref{ch:datapath}).
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\end{itemize}
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