Basic

ww_board_info¶

ww_board_info describes the PCB and its assembly in one value, so ww list and a support case need a single read. It is no_std by default and uses ww_date_time for the build date.

#[ww_trait]
pub trait BoardInfo {
    const BOARD: BoardSummary<'i>;
}

BOARD is a const item, served without a handler and read by a host once per connection. A board read from OTP or straps at boot provides it as a fn (const_model = "BOARD=fn", fn board_board(&self) -> BoardSummary<'_> for board: BoardInfo), a firmware for one fixed board as a Rust const. It never fails; what a device does not know is an empty string or None.

Field	Meaning
`name`	Board series, `B200` (32 bytes)
`revision`	Revision as printed on the board, `B` (8 bytes)
`revision_source`	`Record`, `Strap { value }`, `Assumed` or `Provisional`
`variant`, `bom_variant`, `serial`	Assembly variant, BOM variant, serial number (32 bytes each)
`build_date`	`Option<DateTime>`

Where the revision comes from¶

RevisionSource tells how the firmware knows the revision, which matters for support:

Record - read from a record written in production (OTP, EEPROM, flash).
Strap { value } - read from resistor straps or a revision pin at boot; value is the raw reading, so a host can show what was measured.
Assumed - neither exists: the firmware assumes the revision it was built for. A unit on an assumed revision is a different case from one that read its record.
Provisional - a provisional record a bench or developer wrote in editable storage (flash), standing in for the production record until it is written; not a production record. Added later as an appended variant: older hosts read it as their future_version variant.

Reworks¶

Bring-up boards of one revision differ: some have a cut trace, a jumper or a swapped part that others lack. A device that keeps the list serves it as an optional const item:

#[optional]
const REWORKS: MaxLen<RefVec<'i, Rework<'i>>, MAX_REWORKS>; // 16 entries

`Rework` field	Meaning
`id`	Stable short id, `rework-5`, as in the board's documentation (16 bytes)
`title`	What it is, `cut trace to U3 pin 4` (48 bytes)
`applied`	Whether this unit has it

The id is text, not an Interned (STD-48) index: an index changes with every firmware build and needs the ELF to read, while a rework is a fact about the hardware that any support case must read from any unit. A device that keeps no list leaves it out (omit = ["board.REWORKS"] in ww_codegen!, see optional items): the client answers NotImplementedByDevice without asking. ww info and ww report print the list when it is served. Added in 0.3.0 as an appended item, so older devices and hosts are unaffected.

Device-specific capability flags (a load switch present, a rail powered) stay in the device's own API: they mean nothing on other boards.

BoardSummary has no defmt::Format (its DateTime has none).