[BUG] Postprocessing for J-axis checks I-axis instead

[hm2dev]

Did you test the latest bugfix-2.1.x code?

Yes, and the problem still exists.

Bug Description

When defining a configuration of a printer/cnc with an x, y, z and j axis, but no i axis (e.g. because the rotary axis is parallel to y and not to x), compiling fails because

a) a typo in

Marlin/Marlin/src/pins/pins_postprocess.h

Line 1250 in 311bfc9

#if I_E_INDEX >= MAX_E_STEPPERS || !PIN_EXISTS(J_STEP)

which I assume should be #if J_E_INDEX >= MAX_E_STEPPERS || !PIN_EXISTS(J_STEP) instead.
b) the way the code in

Marlin/Marlin/src/inc/Conditionals_LCD.h

Line 243 in 311bfc9

#ifdef W_DRIVER_TYPE

and following makes assumptions of the number of axes.

Marlin/Marlin/src/inc/Conditionals_LCD.h

Line 251 in 311bfc9

#elif defined(J_DRIVER_TYPE)

Compilation fails with

Marlin\src\pins\pins_postprocess.h:1166:8: error: #error "No E stepper plug left for I!"
    #error "No E stepper plug left for I!"

Bug Timeline

unknown

Expected behavior

Compilation should succeed with only J and no I axis.

Actual behavior

Comilation fails, with

Marlin\src\pins\pins_postprocess.h:1166:8: error: #error "No E stepper plug left for I!"
   #error "No E stepper plug left for I!"

Steps to Reproduce

1. Define a configuration with no i axis and with j axis.
2. Compile

Version of Marlin Firmware

2.1.x

Printer model

not relevant. Example Board: MINIRAMBO_CNC

Electronics

MINIRAMBO_CNC

LCD/Controller

ULTIPANEL

Other add-ons

none

Bed Leveling

None

Your Slicer

None

Host Software

None

Don't forget to include

• A ZIP file containing your Configuration.h and Configuration_adv.h.

Additional information & file uploads

Configuration_adv.zip

[hm2dev]

Upon further investigating and thinking about the axes b) might be working as designed and can be "fixed" by renaming the I axis to B in configuration.h instead of defining an J axis without an I axis.

Marlin/Marlin/Configuration.h

Line 183 in 311bfc9

#define AXIS4_NAME 'A' // :['A', 'B', 'C', 'U', 'V', 'W']

This leaves the typo from a) as bug.
I changed the title accordingly.

If that is so, I can provide a pull request fixing the typo.

[ellensp]

Yes in Marlin the internal axis names must be used sequentially. You then give it the external name you want.

Yes that is a typo you found.

[ellensp]

A pr has been created to fix this typo.

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.