Direct TTL Serial Port Printing on Pi Zero

I have a printer which can use a MKS TFT 2.8, to connect to the printer, it uses one of the AUX ports on the RAMPS board - which is basically, power and TTL Serial - so I want to connect the raspberry pi zero the same way using the on board TTL Serial port.

Here is what I tried
Printer is set to 115200 baud
Ran raspi-config - disable serial port console, re-enabled the uart in /boot/config.txt
set /etc/astrobox/config.yaml to include:

port: /dev/ttyACM0
baud: 115200

And it’s not working. I have of course tried switching the TX/RX around, in case it was a wiring issue. No Joy!

Here’s the kicker, when I download cu (sudo apt-get install cu) and do

cu /drv/ttyACM0 -s 115200

I get an error like the port doesn’t exist or is in use.

Thoughts? suggestions? I’d like to be able to add a Pi Zero to the printer for this and not have to add a usb hub. The bonus being I could keep the printer’s usb port open for flashing the bios as well.

I believe the serial port name on the RPi is “ttyAMA0” ( propapbly full name should be /dev/ttyAMA0 ) not /dev/ttyACM0

Thank you @Jeremy_Proffitt for the info. I was able to connect my Raspberry Pi to my printer over gpio serial using the info provided by you. I should be noted though that @MoBadr was correct in that the interface is ttyAMA0. This page was very helpful. Thanks again!

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EDIT: uff thank God! RPI zero, the port named TTYAMA0 but in the setting /etc/astrobox/config.yaml must be named /dev/serial0 !! Finally :smiley:

Hi, Please advice … Astroprint ttyAMA0 does not show up for Raspberry Pi zero

When i connect a USB-TTL converter so will show… but connect your printer directly to ttyama0 does not show up

raspberry pi zero:
raspbian - latest version
astroprint - latest version

excuse my English

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Just for others trying to get this working on Raspberry Pi Zero:

this is working fine to me:
baudrate: 250000
port: /dev/ttyACM0

However, you need to use the OTG cable, without OTG the /dev/ttyACM0 port will not show up.

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