[Question] Communication problem between ESP3D and the printer

[KristiyanHristov]

I have a problem with communication between ESP3D and the printer. UI claims that command are sent but data is not received back. ("ESP3D says: command forwarded")

Can you help me with debugging this issue?

Thank you!

What I've tried:

1. connecting RX/TX to the CH340 chip directly
2. connecting RX/TX to the screen output
3. connecting RX/TX to the screen output (in place of the screen)
4. using both UART0 and UART1 output ports on the ESP32 (only pins TXD, RXD seem to do something)
5. swapping RX/TX leads as a sanity check
6. changing "Boot sequence" delay to maximum and minimum values
7. Changing "Baud rate"

What I found out:

1. Voltages for RX/TX are 3.3V (no level shifter required)
2. I can connect to the printer via USB and Pronterface
3. I'm using the correct Baud Rate 115200
4. M117 command doesn't output anything on screen
5. Using pins TXD, RXD on the ESP bugs out the screen when both are connected. (meaning there is probably communication happening on those pins)

PRINTER: Anycubic Kobra 2 firmware v3.0.6 Marlin bugfix-2.1.x (Aug 2 2023 14:46:57) PROTOCOL_VERSION:1.0

Thread discussing UART port placement on a similar motherboard https://klipper.discourse.group/t/anycubic-kobra-trigorilla-pro-a-v1-0-4-uart-to-pi-gpio-connection/15432

ESP32: (ESP-WROOM-32) ESP32 Dev Board CH340 - USB-C https://www.robotics.org.za/ESP32-DEV-CH340-C

Flashed using Visual Studio + Platform.io build with esp32dev environment

ESP3D: branch 3.0 { "FWVersion": "3.0.0.a233", "FWTarget": "marlin", "FWTargetID": "20", "Setup": "Enabled", "SDConnection": "none", "SerialProtocol": "Raw", "Authentication": "Disabled", "WebCommunication": "Synchronous", "WebSocketIP": "192.168.0.14", "WebSocketPort": "81", "Hostname": "kobra2", "WiFiMode": "STA", "WebUpdate": "Enabled", "FlashFileSystem": "LittleFS", "HostPath": "/", "Time": "Manual", "Screen": "none", "HostTarget": "files", "HostUploadPath": "/", "HostDownloadPath": "/", "wsID": "0" }

ESP3d-WEBUI: branch 3.0

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[luc-github]

what [ESP420] give as output ? When using UART0 (same as CH340 ) be sure usb is disconnected

[KristiyanHristov]

[ESP420]

Configuration: chip id: 50220 CPU Freq: 240Mhz CPU Temp: 46.7C free mem: 188.69 KB SDK: v4.4.4 flash size: 4.00 MB size for update: 1.87 MB FS type: LittleFS FS usage: 104.00 KB/128.00 KB baud: 115200 sleep mode: none wifi: ON hostname: kobra2 HTTP port: 80 Telnet port: 23 WebDav port: 8181 wifi mode: sta mac: 08:D1:F9:E1:2C:C4 SSID: dd-wrt signal: 100% phy mode: 11n channel: 1 ip mode: dhcp ip: 192.168.0.14 gw: 192.168.0.1 msk: 255.255.255.0 DNS: 1.1.1.1 ap: OFF mac: 08:D1:F9:E1:2C:C5 ntp: OFF serial: ON (UART0) authentication: OFF notification: ON (none) targetfw: marlin FW ver: 3.0.0.a233 FW arch: ESP32 ok

[KristiyanHristov]

yes USB is disconnected

[luc-github]

what baud rate Marlin is set in your configuration.h of Marlin ?

[KristiyanHristov]

I don't build my own printer firmware, but if this is the one they officially shipped https://github.com/ANYCUBIC-3D/Kobra2/blob/Kobra2_V3.0.6/source/Marlin/Configuration.h

its #define BAUDRATE 115200

It's the same rate I use to connect via USB Pronterface

[luc-github]

well if you cannot be sure about baudrate it is hard to know if that is the root cause or not but if it can use it on Pronterface - should be ok

I suggest you to find a serial/usb adapter (something like https://www.amazon.com/HiLetgo-CP2102-Converter-Adapter-Downloader/dp/B00LODGRV8/ref=sr_1_1_ssp) and check if your Printer board wiring is correct and can communicate with your pc using serial terminal

[luc-github]

also such device can be also used on esp32 to test the esp32 uart pins also

[KristiyanHristov]

Ok. I'll source one locally. Will a six pin one do the job?

[luc-github]

yes, you only need 3.3v gnd txt rxt pins, this will help you to debug the communications

[KristiyanHristov]

Ok, I got the adapter and setup the terminal. What is the expected behavior? When connected to the printer (UART for the LCD screen). I get some output:

[luc-github]

nope that is not the Marlin output - do you have the same when you connect your printer and the serial terminal by the USB port ?

[KristiyanHristov]

No. When connected via USB I can send M503 and get the config.

[KristiyanHristov]

That probably means I need to find another place to hook in to the board until i get a Marlin response for "M503"?

[luc-github]

well you found the root cause - the usb adapter do same as the CH340 so output should be same - it means the usb adapter is not connecting to rx/tx - to test use M105 or M114 or M115

[KristiyanHristov]

Well, I have to do some poking around :) You can close the ticket, I'll probably add a comment with my findings.

Thank you for your time and patience!

[luc-github]

Good luck then ^_^

[KristiyanHristov]

Everything is now running. I used pins 2 and 3 of the CH340.

[luc-github]

cool feel free to add your board to the list with instruction and images: https://esp3d.io/esp3d/v3.x/hardware/system_boards/index.html

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