# Help with RPi Zero 2w UART connection **URL:** \ **Category:** General Discussion\ **Created:** [May 6, 2024, 11:52am UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292 "2024-05-06T11:52:19Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![ProControl](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@ProControl](https://klipper.discourse.group/u/ProControl)\ **Post date:** [May 6, 2024, 11:52am UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/1 "2024-05-06T11:52:19Z")
### Basic Information: Printer Model: ender 3 Pro MCU / Printerboard: creality 4.2 7 Host / SBC : **Host** (aarch64, 64bit) OS: Debian GNU/Linux 12 (bookworm) RPi Zero 2w klippy.log : attached [klippy.log](https://klipper.discourse.group/uploads/short-url/2cAeGbHb5APUmuDDFrE90XbyFqW.log) (509.3 KB) * * * Hi I tried to use Klipper on my Ender 3 Pro connection over UART I do everything but I am Unable to connect to MCU 🙃🥲 ```auto [mcu] serial: /dev/ttyAMA0 # For UART Connection # serial: /dev/serial/by-path/platform-3f980000.usb-usb-0:1:1.0-port0 # USB Connection restart_method: command ``` ![Schematic](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/3/394e3e96aa652026692d2c11bda93ad159fc84d7.png) ![Screenshot 2024-05-06 135639](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/6/674a52ed0e8e64d04cca0db0b0e704283f84996b.png) ![Screenshot 2024-05-06 135829](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/a/a33083c5235d5a678bdc2023a37f8e87847c9a5f.png) ![Screenshot 2024-05-06 140106](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/b/b9d4fdcb65cab08a728c554852ccb89c6b165d1b.png) Note: I know I can use it over USB but I prefer to use this setup for compact size Also, I followed this [Klipper and the RPI-zero](https://www.youtube.com/watch?v=AtW3GqkKUz8) but It’s old, things have changed What do I miss ? Thanks ---
**Author:** ![TheFuzzyGiggler](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/thefuzzygiggler/32/12313_2.png) [@TheFuzzyGiggler](https://klipper.discourse.group/u/TheFuzzyGiggler)\ **Post date:** [May 6, 2024, 12:14pm UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/2 "2024-05-06T12:14:00Z")
Before we get too far, Two very important things. 1.) Most importantly, are you sure the UART pins on your printer control board are 3.3V? Raspberry Pi’s are not 5v tolerant, you’ll kill your GPIO pins if you apply 5v to it. 2.) Are you sure your board has enough current to power the Pi Zero that way? The recommended power supply for the Pi Zero 2W is 5V/2.5A which I’d be very surprised if those two pins can put out. ---
**Author:** ![ProControl](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@ProControl](https://klipper.discourse.group/u/ProControl)\ **Post date:** [May 6, 2024, 3:50pm UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/3 "2024-05-06T15:50:25Z")
@TheFuzzyGiggler > [@TheFuzzyGiggler](#): > > 1.) Most importantly, are you sure the UART pins on your printer control board are 3.3V? Raspberry Pi’s are not 5v tolerant, you’ll kill your GPIO pins if you apply 5v to it. > > Suer by 5V 3.3V DC Logic Level Converter Bi-Directional > > ![Screenshot 2024-05-06 184359](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/4/46c2a2197dd663d922698982cde642ebdcde8d6b.png) > > 2.) Are you sure your board has enough current to power the Pi Zero that way? The recommended power supply for the Pi Zero 2W is 5V/2.5A which I’d be very surprised if those two pins can put out. > Sure by DC-DC Step-Down Module > ![Screenshot 2024-05-06 184851](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/b/bb2edee2f5e7daabe8527883387a53484fe727e8.png) 1 ---
**Author:** ![TheFuzzyGiggler](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/thefuzzygiggler/32/12313_2.png) [@TheFuzzyGiggler](https://klipper.discourse.group/u/TheFuzzyGiggler)\ **Post date:** [May 6, 2024, 4:39pm UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/4 "2024-05-06T16:39:05Z")
You say a Step-Down module, are you pulling power from the power input of the controller board or from the pins in the diagram? And this is me just kind of nitpicking, so take it with a grain of salt cause it’s your setup not mine… All this is easier than just using a usb cable? But to get back on subject… [https://www.raspberrypi.com/documentation/computers/configuration.html#primary-uart](https://www.raspberrypi.com/documentation/computers/configuration.html#primary-uart) > Primary UART > On the Raspberry Pi, one UART is selected to be present on **GPIO 14 (transmit) and 15 (receive) - this is the primary UART**. By default, this will also be the UART on which a Linux console may be present. Note that GPIO 14 is pin 8 on the GPIO header, while GPIO 15 is pin 10. > . ![image](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/5/5abafb974e1d3f2bff7c89743bc9f2978c803443.png) ![image](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/f/f2e4610715b389943d0e71ad5206e2da20141e97.png) Primary UART on the Pi Zero 2 is ```auto /dev/serial0 ``` The one you have in your config is for the PL011 UART which is the secondary on the Pi Zero 2. ---
**Author:** ![ProControl](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@ProControl](https://klipper.discourse.group/u/ProControl)\ **Post date:** [May 6, 2024, 9:53pm UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/5 "2024-05-06T21:53:41Z")
@TheFuzzyGiggler > [@TheFuzzyGiggler](#): > > You say a Step-Down module, are you pulling power from the power input of the controller board or from the pins in the diagram? \> form PSU > > And this is me just kind of nitpicking, so take it with a grain of salt cause it’s your setup not mine… All this is easier than just using a usb cable? > Sure , I know that I want to use a USB port for the cam with Otg without using hub for both cam and printer what is your suggestion to modify config or other to get work ? ---
**Author:** ![TheFuzzyGiggler](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/thefuzzygiggler/32/12313_2.png) [@TheFuzzyGiggler](https://klipper.discourse.group/u/TheFuzzyGiggler)\ **Post date:** [May 6, 2024, 11:24pm UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/6 "2024-05-06T23:24:32Z")
Try changing your config to this so it points to the right UART ```auto [mcu] serial: /dev/serial0 Connection restart_method: command ``` Also, you might have some issues trying to use a Pi Zero for Klipper and a Webcam. I haven’t tried it myself but from what I’ve read it bogs down the system quite a bit. Also be careful on your power draw if you try to use a webcam as well. The Pi Zero 2 skirts the line on jusssst being powerful enough to possibly get away with it though. ---
**Author:** ![ProControl](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@ProControl](https://klipper.discourse.group/u/ProControl)\ **Post date:** [May 14, 2024, 10:52am UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/7 "2024-05-14T10:52:27Z")
> [@TheFuzzyGiggler](#): > > `/dev/serial0` finally back to USB ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\ **Post date:** [July 13, 2024, 10:53am UTC](https://klipper.discourse.group/t/help-with-rpi-zero-2w-uart-connection/16292/8 "2024-07-13T10:53:03Z")
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