[3D Printing] Wireless Management TF Card Remix

************************20240201**************************
1. The serial port garbled characters are due to a grounding issue, not related to the board itself;
2. The speed issue is due to IO46; the datasheet mentions a weak pull-down, which might be affecting performance;
3. It has been identified that the SD card is not actually powered off and restarted because the pin is not completely closed, preventing free switching between ESP32 and MEGA. A new board has been tested. I saved it to a private project, but I'm not very familiar with the process. It seems the only solution is to re-share that project. I don't know how to import it directly here.
 
************************20240121**************************
I tried flashing ESP3D and encountered a few problems
: 1. I couldn't connect pins 2 and 3 (serial1) on the RAMPS as instructed on the ESP3D homepage because the RX is directly connected to the serial chip RX on the Mega2560, which has an internal pull-up of 5V. During communication, the low level is not low enough to read the data.
2. In Marlin, I set the serial port to 2 and connected to serial2 on the RAMPS. The connection was successful, but in the ESP3D web interface, the data read from the Mega2560 would intermittently show garbled characters. The oscilloscope showed no problems with the voltage levels. Sending GCODE and the printer responded normally. Anyway, it works for now.
3. I flashed the original code of this board, which originally could reach speeds of 500K. After flashing ESP3D using SDIO 4bit, the same board only reached speeds of around 100K. I looked at the code and the parts about SDMMC open and file write were the same in both programs. I don't know why the upload speeds of the two programs are so different on the same board.
 
************************20231210**************************
ESP3D has already explained the software and communication solutions for different boards quite clearly: https://esp3d.io/esp3d/v3.x/features/index.html. Here, I mainly focus on Ramps for self-assembled printers; suitable for those with low printing volumes who enjoy playing with hardware and software. For high volumes, I recommend Klipper.
Actually, I've seen a more feature-rich version, but I prefer the concise solution by the original author, lin_xiandi.
Features of this solution:
1. A serial port is provided for direct connection to RAMPS, which can be used with ESP3D - currently un-software tested;
2. An integrated level conversion module is used, employing a 5-pin direct connection to RAMPS, eliminating the need for a ribbon cable;
3. The ESP32 is read/written via SDMCC, while the printer is read via SPI, so only one analog switch is used;
4. An LED is added, which is constantly lit during initialization, flashes continuously when not connected to the network, and turns off after server setup, used to determine the status;
5. Power supply is simplified, using a Schottky diode after the USB port to prevent backflow, and an XH2.54 2-pin 5V power input port is added, which will be supplied with 5V by a DC-DC converter from another DIY RAMPS expansion board; therefore, many power switching selection and control components have been eliminated;
Currently, there is a bug that is still being addressed: after the printer reads a card, it cannot switch back to the ESP32, and once the card is operated, it will lock, and powering off is ineffective; the card must be removed. File transfers can only be processed after power-on, not printed first.