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CTC / Mightyboard serial Wifi conversion fail

This is just a quick post while I'm working on something bigger.
I've tried to get a NodeMCU module to interface to the serial port on my CTC Dual/Bizer printer, which uses a Rev G(?) Mightboard motherboard. Unfortunately, the main serial port is not exposed, just UART1.

The easiest way I've found to get to the TX/RX lines was to piggyback on the resistors just before the ATMega8U chip:


The 8U is used as a serial to USB converter.

5V and ground can be picked up from the exposed UART header, pictured bottom middle:


I tried to use the ESP3D firmware but it only works with boards that support G-Code, not X3G. So I abandoned the project due to lack of time.



The pictures above are from a few weeks ago but just yesterday I managed to put a hole in my 8U chip, no idea how that happened:


So now I was forced to use my makeshift serial connection. I tried both possible solutions:

https://github.com/beckdac/ESP8266-transparent-bridge

https://github.com/jeelabs/esp-link

Unfortunately neither of them worked, the data gets corrupted after a few commands sent to the printer and the printer does not respond to serial input anymore.

However, using a standard CH430 USB converter does the job, with the jumper set to 5V.

I could probably get the ESP8266 working, but need to check whether it needs some voltage converter (UART on ESP8266 is 3.3V, on Mightyboard it's 5V) or some resistors.


In case you decide to try it yourself, to set up a transparent serial-TCP bridge on Windows, I've used com0com with the following batch file:

com2tcp.exe --baud 115200 --ignore-dsr --telnet \\.\CNCB0 192.168.178.72 23pause


Not sure if the ignore-dsr option is needed or if it does more harm than good, haven't experimented too much.

Comments

  1. Good morning, the USB port of my CTC printer has failed, I'm reduced to using the SD card slot, which is mechanically starting to fail.

    I'm printing as many face shields as I can for local healthcare workers and had a good system going with octoprint to notify me when the print bed needed to be cleared and restart printing.

    I see you managed to tap into TX and RX of the board with a USB to Serial adaptor. I would like to attempt the same and reconnect the printer to my Raspberry Pi.

    Could you clarify where to connect the TX & RX lines for me please?

    Many thanks!

    ReplyDelete

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