Connect MKS-SGEN_L-V2 and RPi3 via RX TX

General Discussion
1

Hello!
No connection MKS-SGEN_L-V2 and RPi3 via RX TX, using port AUX-1.

3-pin connector cable
MKS-SGEN_L-V2 GND(black) TX(blue) RX(red) → RPi3 GND(black) TX(red) RX(blue)

/boot/config.txt
add
dtoverlay=pi3-miniuart-bt

/boot/cmdline.txt
delete
console=serial0,115200

printer.cfg

[mcu]
serial = /dev/ttyAMA0
restart_method = command

make menuconfig

[*] Enable extra low-level configuration options
    Micro-controller Architecture (LPC176x (Smoothieboard))  --->
    Processor model (lpc1769 (120 MHz))  --->
[*] Target board uses Smoothieware bootloader
    Communication interface (Serial)  --->
(250000) Baud rate for serial port (NEW)
[ ] Specify a custom step pulse duration (NEW)
()  GPIO pins to set at micro-controller startup (NEW)

Using a USB cable, there is a connection.

klippy.log

2

Installed Octoprint and Marlin, the connection via RX TX works.

I installed the klipper on octoprint, the connection via the USB cable is working.

Configured via RX TX, the connection does not work.

in the logs the same connection error.

Starting serial connect
Timeout on connect
Wait for identify_response
Traceback (most recent call last):
  File "/home/pi/klipper/klippy/serialhdl.py", line 65, in _get_identify_data
    params = self.send_with_response(msg, 'identify_response')
  File "/home/pi/klipper/klippy/serialhdl.py", line 249, in send_with_response
    return src.get_response([cmd], self.default_cmd_queue)
  File "/home/pi/klipper/klippy/serialhdl.py", line 306, in get_response
    cmd_queue)
  File "/home/pi/klipper/klippy/serialhdl.py", line 241, in raw_send_wait_ack
    raise error("Serial connection closed")
error: Serial connection closed
3

Hi there. Not sure if it’s still needed, but I suggest you to lower the baud rate to 115200. I have similar board (SKR 1.4 turbo), and managed to link mcu to Pi using this baud rate, and it wasn’t working with 250k BR.

4

There is currently an issue with the lpc176x mcus and UART wiring - https://github.com/KevinOConnor/klipper/issues/4194

It is never a good idea to use a serial baud rate other than 250000 with klipper. Any advice found online that says otherwise is wrong.

-Kevin