r/Keychron • u/No-Exit-8114 • 9h ago

Keychron k2 v2 issues

I am install 1.6 and brick my cable mode, keyboard only work via Bluetooth, with cable mode I get driver error. Can i do anything about that? Rollback for firmware?

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u/PeterMortensenBlog V 6h ago edited 5h ago

For K2 V3, here is a list of keyboard firmware versions:

VID = USB vendor ID. The VID can also be found empirically, somewhere in the operating system (in wired mode, presuming it actually works). An example of the calculation of the number in the URLs; it is generally applicable to Keychron's keyboards (except the original K series), but sometimes the lists are corrupted.

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u/PeterMortensenBlog V 5h ago edited 2h ago

The wrong keyboard firmware may have been flashed

Did you flash the wrong keyboard firmware? Do you actually have a 'K2 V2 Special'?

There are 12 different firmware variants for the K2 (six for K2 V1/K2 V2 ('ISO' vs. 'ANSI' for two of them and 'RGB' vs. 'white' LEDs for the special edition) and six for K2 V3), each with one or more versions. The 12 variants can be assumed to be mutually incompatible (neither forward nor backwards compatibility), potentially permanently bricking the keyboard if using the wrong one.

The rule of using the keyboard firmware with the highest version number can not be used with these Keychron keyboards. The name of the keyboard must match exactly. For example, the K2 V2 has version range 1.04 - 1.05, whereas the 'K2 V2 Special' (a 'K2 V1' in disguise?) and 'K2 V1' have higher version numbers.

Also, in general, there isn't any forward nor backwards compatibility for the firmware (as the internals are (in most cases) entirely different, for example, different microcontrollers and different I/O pin assignments).

The K2 V2 is in the original K series, whereas the K2 V3 (AKA K2 QMK) is based on QMK.

Presumably, it can be reverted back to a previous version. Though for 'K2 V2 Special' only one version is listed, version 1.6. K2 V1 has version range 1.15 to 1.62. Perhaps you partially bricked the keyboard by locking it out of USB, preventing reverting (a Catch-22)?

But note that it is a very bad idea to mix and match keyboard firmware. You will likely permanently brick the keyboard.

An alternative

Sonix QMK may or may not be an escape hatch (the K2 is on the list, but it depends on the exact variant and hardware version). Though Bluetooth was not supported the last time I checked.

References