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Oliver Walter ddfda14085 Add USB-RS485 bridge and PC-side test suite
Makes end-to-end verification of the bus possible with a spare RP2040 and
no dedicated RS485 dongle.

bridge/ turns a second Pico into a transparent USB-to-RS485 bridge. It is
deliberately protocol-agnostic: bytes from USB go out on the pair, bytes
from the pair go back up USB, and it knows nothing about frames,
addresses or CRCs. A protocol-aware bridge could have a bug that happens
to agree with the node's own, which would defeat the point of using it as
a test instrument. It also needs no register-level code — it never has to
delimit a frame, and the one thing it does need, knowing that the final
stop bit has cleared the shifter before releasing DE, rp2040-hal exposes
as uart_is_busy().

tools/wiredsensor.py is an independent implementation of the wire format,
written from the specification in README.md rather than sharing code with
wiredsensor-core. Shared code would let a framing or CRC bug cancel out
and every test pass regardless. Cross-checked: it reproduces the
CRC-16/MODBUS catalogue vector and builds byte-identical frames to the
Rust side for all five documented examples.

Its `test` subcommand covers what host tests structurally cannot, all of
it timing-dependent: that malformed and mis-addressed frames leave the
node silent rather than colliding with whoever was actually addressed,
that the driver-enable turnaround leaves replies intact, and that no
state leaks between back-to-back frames.

Uses one wiring diagram for both boards, since the bridge mirrors the
node's GPIO0/1/2 assignment. Frames must fit one 64-byte USB packet, as
each host write becomes exactly one DE-bracketed transmission; every real
command is at most 21 bytes.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-28 20:31:30 +02:00

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[workspace]
resolver = "2"
members = ["core", "firmware", "bridge"]
[workspace.package]
version = "0.1.0"
edition = "2021"
license = "MIT OR Apache-2.0"
[workspace.dependencies]
wiredsensor-core = { path = "core" }
defmt = "1.1"
# Cortex-M0+ has no hardware divide and a small cache-less flash path, so even
# debug builds want size optimisation or timing-sensitive paths get sloppy.
[profile.dev]
codegen-units = 1
debug = 2
debug-assertions = true
incremental = false
opt-level = "s"
overflow-checks = true
[profile.release]
codegen-units = 1
debug = 2 # keep DWARF for probe-rs/defmt; it is not flashed
debug-assertions = false
incremental = false
lto = "fat"
opt-level = "s"
overflow-checks = false