Creality Ender 3 Pro – 4.2.X CPUs – 512K swapped out for 256K – WARNING POTENTIAL FIRE HAZARDS

[garaysantiago]

Did you test the latest bugfix-2.0.x code?

Yes, and the problem still exists.

Bug Description

In Discord server a user was working on their machine and was having issues with the firmware. They posted a picture of the board and it revealed a lesser STM32 part number on that board. The 4.2.2 and 4.2.7 boards have all shipped with the STM32F103 RET6 CPUs since release. Now there is confirmation that 4.2.2 boards have shipped out from Creality with lesser 256K parts on them that are NOT safe to use with current Marlin and Unified firmware builds.

There are 4.2.2 (we would assume that 4.2.7s may have the lesser CPUs soon, we will be adding part number checks to the 4.2.7s that we sell going forward to make sure they have 512K parts on them) out in the wild with STM32F103 RCT6 CPUs. These CPUs are 256K parts whereas the RET6 versions were 512K parts.

Bug Timeline

No response

Expected behavior

No response

Actual behavior

No response

Steps to Reproduce

No response

Version of Marlin Firmware

2.0.9.3

Printer model

Ender 3 Pro

Electronics

4.2.2 and 4.2.7 boards have all shipped with the STM32F103 RET6 CPUs since release

Add-ons

No response

Bed Leveling

No response

Your Slicer

No response

Host Software

No response

Additional information & file uploads

No response

[thisiskeithb]

Have any other hardware changes been made? Adding a 256K variant is straight forward.

[tome9111991]

Swap from RET6 to RCT6

https://www.th3dstudio.com/2022/01/16/creality-4-2-x-cpus-512k-swapped-out-for-256k-warning-firmware/

[jbuck2005]

Pardon my ignorance but why the flag "potential fire hazard" ?
Are you proposing that the reduced memory space will force users to forgo the thermal runaway protection mechanism?

[thisiskeithb]

Pardon my ignorance but why the flag "potential fire hazard" ?

Overflashing could potentially lead to unexplained lockups with the heaters on.

I didn’t experience that issue personally, but some folks did, so YMMV.

[jbuck2005]

Oh wow. Fair point!! I had not even considered that the firmware flash procedure would fail to check for out-of-bounds writes. Good lord.

[thisiskeithb]

I've created a PR, so please test & report any issues: #23599

[github-actions]

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