Probe Info and Firmware Version

Source: GetProbeInfo, ProbeInfo and the version helpers in src/commands/control.rs; WchLinkVariant in src/probe.rs.

`0x0d / 0x01` — GetProbeInfo

Request: 81 0d 01 01.

Response payload (ProbeInfo::from_payload requires at least 3 bytes):

Offset	Field	Notes
0	`major_version`	Raw major byte as reported by the probe
1	`minor_version`	Raw minor byte (may exceed 15 — see below)
2	`variant`	Only interpreted when the payload is 4 bytes long; otherwise wlink assumes `Ch549`
3	—	Present in the 4-byte form; meaning `unverified`

Example: 82 0d 04 02 0f 02 00 → major 0x02, minor 0x0f, variant 0x02 (WCH-LinkE-CH32V305), with a fourth payload byte of unknown meaning. A 3-byte payload carries no variant and makes wlink assume Ch549.

Firmware version encoding

The probe does not report a decimal version. Its two bytes are a packed value, and WCH’s tooling displays versions as major * 10 + minor. This is why README says “firmware version 2.15 is actually v35”.

For raw bytes (major, minor):

packed        = 16 * major + minor
version_code  = if packed < 0x30 { 10 * major + minor } else { packed - 12 }
display       = (packed >> 4, packed & 0x0f)

version_code is monotonic and is what wlink uses for all comparisons. display_version reconstructs the human-readable version by treating the packed value as two nibbles, so an “impossible” minor carries into the major.

Raw bytes	`packed`	`version_code`	Displayed as	Note
`02 08`	`0x28`	28	2.8	Older firmware
`02 0f`	`0x2f`	35	2.15 (v35)	Current baseline in README
`02 16`	`0x36`	42	3.6	wlink source spells newer builds as `2.22`
`02 0a`	`0x2a`	30	2.10 (v30)	First firmware with SDI print

Minimum firmware versions used by wlink

Constant	Value	Purpose
`MIN_FW_VERSION_CHIP_INFO_V2`	29 (`v2.9`)	Use `GetChipInfo::V2` (`0x11 / 0x06`) instead of V1
`MIN_FW_VERSION_CH32V205`	42 (`v3.6`, sometimes written `2.22`)	First firmware that reports the new-generation CH32V205 family (`0xce`) correctly

Older firmware misdetects CH32V205 as CH32V20X with garbage ChipID/ESIG; wlink emits a warning but continues.

Variant codes and capabilities

WchLinkVariant::try_from_u8 accepts:

Byte	Variant
`0x01`	`Ch549`
`0x02`, `0x12`	`ECh32v305`
`0x03`	`SCh32v203`
`0x05`, `0x85`	`WCh32v208`
other	`Error::UnknownLinkVariant`

Variant	Mode switch	Power output	SDI print	Chip restrictions
`Ch549`	no	no	no	No CH32V003 / CH32X035 / CH643
`ECh32v305`	yes	yes	yes	none
`SCh32v203`	yes	no	no	none
`WCh32v208`	yes	yes	no	No CH56X / CH57X / CH582 / CH59X

Hardware variants (historical table)

The old protocol.md listed these; they are retained here for orientation but have not been re-verified against current hardware.

Probe MCU	Variant	Note
CH549	WCH-Link-R1-1v1	Switch mode by reflashing firmware
CH32V305F	WCH-LinkE-R0-1v3	Switch mode by button or EEPROM setting
CH32V203	WCH-LinkS-CH32V203	—
`unverified`	WCH-LinkB	Hardware MCU unknown

See USB Transport for VID/PID and mode-switch frames.

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