PCB Creality 4.2.2 (STM32F103RET6) and Marlin FW relations

Now one idea (project) of converting the Cube 2 device (3D System) to simpler materials and preparing for printing has taken over me. Then I'll change it back to something else.
Cube 2, PCB Creality 4.2.2, LCD 12864LW-10 I got inexpensively which I will replace with stock HW of Cube2.
1. Firmware I builded bugfix 2.1.X. But something goes wrong, the display lights up but does not show. I can flashed third-party firmware for Ender3 to the board via SD.
2. Is it possible to find the source code or the bootloader bin file for Creality 4.2.2?
2. Downloading via SD - is this the only way? I can use ST-Link, but a simple connection to the processor was unsuccessful. Rather, the SWDIO and SWCLK pins are reassigned, need to try the connection method Connection Under Reset. To do this, make a wire to the pin RESET of STM32
3. What display should be indicated in the configuration if it is signed as 12864LW-10? It's from an Ender 3 with rotary encoder.
4. What is the difference between building maple_env and without "maple"?

Thanks for attentions

Yuri

Edited 1 time(s). Last edit at 04/14/2023 12:33AM by CatRovacer57.

1) no question here.. Firstly check the MPU on the controller. read the part number. If you build for a stm32f103re and it is a stm32f103rc it will not boot and the screen will not start.
Has been seen with STM32F103RC, STM32F03RE, GD32F103RE and GD32F303RE

2) no source, a booloader.bin is available Creality-4.2.2.bootloader.bin

second 2) Its a stm32, you can use any standard stm32 upload methods. but using sdcard is easiest, and is very hard to brick it that way. very easy to brick it with st-link.

3) CR10_STOCKDISPLAY you also need to add #define RET6_12864_LCD to Your configuration.h

4) maple is older legacy framework, non maple is newer, less buggy and smaller STM32duino framework.

Edited 4 time(s). Last edit at 04/14/2023 12:55AM by Dust.

Which offset need for binary location in flash memory for target?
where is it indicated in the platformio? Are there files for link like.ld?

#elif MB(CREALITY_V4)
  #include "stm32f1/pins_CREALITY_V4.h"         // STM32F1                                env: STM32F103RE_creality env: STM32F103RE_creality_xfer env: STM32F103RC_creality env: STM32F103RC_creality_xfer env: STM32F103RE_creality_maple

So look at the listed build envs:

which leads to

#
# Creality (STM32F103Rx)
#
[STM32F103Rx_creality]
extends                     = stm32_variant
board_build.variant         = MARLIN_F103Rx
board_build.offset          = 0x7000
board_upload.offset_address = 0x08007000

wich shows you the address
bootloader is from 0x08000000-0x08006FFF

also from this you see MARLIN_F103Rx wich leads tou to buildroot/share/PlatformIO/variants/MARLIN_F103Rx
Which contains ldscript.ld

Edited 1 time(s). Last edit at 04/14/2023 12:05PM by Dust.

Thanks for the bootloader, ive search long time for this.
Few years ago i bricked mine, i got it working again without bootloader. (but every firmware update i had to use st-link)

Now i can use the sdcard again for new firmware.