The pin crosses libavr's phase 6 - the renamed system surface, the named
serial configs, the receiver-tolerance table, the paged SPM receipts -
and every loader image comes out size-identical: the full matrix on six
representative chips (the exhaustive cross product on three of them),
the stock and autobaud columns untouched, the four tsb tiers back on
their recorded floors at 510/526/638/836.
Byte parity was not free, and the two libavr defects it surfaced were
fixed there rather than absorbed here. The EEPROM write procedure's
step 2 - the SPMEN spin - had landed unconditionally and cost every
build six bytes for a wait a polled loader can never take; it is scoped
now, and the loaders state the datasheet's own omission clause
(spm_interlock::omitted, DS40002061B 8.6.3). The blocking page
erase/write grew an internal wait the tiers' settle() already provides,
so the tiers issue the command form and pureboot keeps its host-driven
sp_spm path.
What the port states rather than inherits: the stock 115200 at 16 MHz
sits +2.1 % past the receiver-tolerance table libavr now holds rates
to, so the hardware links say .allow_baud_error = true - the same
2.5 % envelope pureboot_baud_feasible() has always enforced, proven on
silicon across the fleet. rx_ready() reads readable() now.
Alongside the pin: rule 33's ASCII sweep over every source (docs keep
their typography), rule 34's InsertBraces in .clang-format with the
tree reformatted, std::array over the simavr runners' raw buffers, and
the stale Studio size in ide/README.md replaced by the claim its
check-flags gate actually holds.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Four cuts, none touching what the loader can do. The entry stub stops
re-doing the reset logic's own SP write where the datasheet guarantees
RAMEND (stack::hardware — the classic megas keep theirs). The autobaud
unit moves into GPIOR2:GPIOR1 wherever the chip has the pair: one-word
accesses, no RAM object, and the host's measured-clock peek follows it
by version and geometry. 'J' rides the unified decode, carrying a
selector it ignores so its address is the same two reads as every other
command — the tool sends the bare form to older residents. run_app stops
insisting on a body of its own. The fleet lands at 358–410 B stock and
438–474 B autobaud; the tightest image in the space — the 1284s'
autobaud on a USART's own pins with the OSCCAL trim — drops from 510 to
484 of its 512. Every chip's suite is green on the wire that changed,
and the README's table is machine-checked against the built images.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The fixed-baud window counted down a uint32 where almost every window fits
24 bits; the countdown now takes avr::uint24_t when the poll budget allows
(the autobaud budget's own choice), uint32 past 16.7M polls — four bytes
off every fixed-baud image on every chip, the full suites green on the
changed window. The README size table is refreshed — its autobaud column
had also gone stale by the no-assembly pass's measurement-loop win, which
nothing gated: sizes.py check-readme now runs as the gate's final stage,
where every tree is freshly built and the table can actually be held.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The pin the whole history now encodes becomes the primary route: the
submodule default replaces FetchContent and the unpinned forge fallback,
LIBAVR_ROOT stays as the tandem-development override, the presets already
take the toolchain file from the submodule, and the Studio projects anchor
their include path there — correct by construction. The version tags and
the one-command historical build are documented beside the version map.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
master carries bootloader.atsln, so main does too. Two projects, because a
.cppproj is one binary at one flag set and this build has hundreds: the stock
328P pureboot loader (USART0 at 115200 on a 16 MHz crystal), and the tsb_asm
tier that occupies the same 512-byte section master's own tsb project targeted.
Both come out byte-identical to the Ninja build — 404 B and 510 B of .text —
in both configurations.
Debug keeps -Os and adds only -gdwarf-4. A loader's section is a correctness
bound, and -Og builds this source to 590 B: the link at 0x7e00 accepts that
without a diagnostic, 78 bytes past flash end, where rcall/rjmp wrap modulo
flash size and the image dies just after activation. Debug info costs no flash,
so the optimisation level stays where correctness needs it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
