# Problems with USART1 **URL:** \ **Category:** General Discussion\ **Created:** [July 2, 2025, 3:48pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093 "2025-07-02T15:48:57Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 3:48pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/1 "2025-07-02T15:48:57Z")
### Basic Information: Printer Model: AnetA8 plus MCU / Printerboard: btt skr3 Host / SBC Raspberry pi1 klippy.log [klippy.log](https://klipper.discourse.group/uploads/short-url/gfa7eZT5c2O384SFz17eXVC8rrD.log) (105.7 KB) _Fill out above information and_ **_in all cases attach your_ `klippy.log` _file_** (use zip to compress it, if too big). _Pasting your_ `printer.cfg` _is **not** needed_ _ **Be sure to check our “Knowledge Base” Category first. Most relevant items, e.g. error messages, are covered there** _ Hello everyone, I have this problem. I used to connect the Raspberry Pi to the printer via USB, but then I decided to connect it through the TFT port USART1. I followed the Klipper instructions and have tried several times, but at the moment I can’t get the Raspberry Pi to connect to the SKR3. Can anyone help me?" ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [July 2, 2025, 4:22pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/2 "2025-07-02T16:22:38Z")
You’re going to need to provide more information. 1. What is the actual Main Controller Board are you using (“btt skr3” can mean quite a few different ones)? 2. You’re using a Raspberry Pi 1? You know that for Klipper, a Raspberry Pi 3 is considered the minimum. 3. Where did you get your information for making the connection? 4. How did you make your serial connection between the rPi and the skr3? Photos would be helpful here. Big question I have, is if you had a working USB connection between the rPi and the skr3, why did you change it? ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 6:34pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/3 "2025-07-02T18:34:21Z")
I’ll give you some answers to your questions: 1 The board is a BTT SKR3 with the SMT32H743 chip. 2 I’m not sure, maybe it’s because it lacks WiFi? I solved it with an external USB antenna. 3 I got the information from this website that was suggested to me [SKR-3/Firmware/Klipper/README.md at master · bigtreetech/SKR-3 · GitHub](https://github.com/bigtreetech/SKR-3/blob/master/Firmware/Klipper/README.md) 4 ![skr3 pin](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/0/d/0d3929358037b1e3b5fcc03d031f1b6051baae42.jpeg) I built a box for the printer to hold both the SKR3 and the Pi1, but the USB cable went around the outside, and if I accidentally bumped it, the Raspberry Pi would turn off. I hope I’ve been clearer so that you can help me in some way. ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [July 2, 2025, 8:00pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/5 "2025-07-02T20:00:58Z")
> [@hfintegrale](#): > > I’ll give you some answers to your questions Please answer all questions as completely as possible - providing more information and anything that you think might be helpful is never a problem. There is nothing that you can do that we haven’t seen before and we won’t embarrass you over bad wiring or whatever. Things will go smoother and faster if you don’t turn this into an episode of “House”. > [@hfintegrale](#): > > 1 The board is a BTT SKR3 with the SMT32H743 chip. Okay,. I’ve found the information on it. > [@hfintegrale](#): > > 2 I’m not sure, maybe it’s because it lacks WiFi? I solved it with an external USB antenna. Actually it’s because Raspberry Pi’s that are earlier than the 3 do not have sufficient computing power to handle Klipper. Can you confirm that you actually have a Raspbery Pi 1 - a picture of it would be nice. A picture including the Serial connection to the SKR 3 would be even better. This could be the cause of your problems - when I looked through your `klippy.log`, there are a lot of `mcu 'mcu': Timeout on connect` errors. > [@hfintegrale](#): > > 3 I got the information from this website that was suggested to me > [SKR-3/Firmware/Klipper/README.md at master · bigtreetech/SKR-3 · GitHub](https://github.com/bigtreetech/SKR-3/blob/master/Firmware/Klipper/README.md) This is three years old. Did you follow the instructions explicitly and what deviations did you make? It look like youi’ve built new Klipper firmware for your board using the Raspberry Pi - this is a good thing. Did you run `ls /dev/serial/by-id` to get your `serial = /dev/ttyAMA0` connection? Which pins on the Raspberry Pi are you connecting to? > [@hfintegrale](#): > > 4 → Image from a website Not what I was asking for. I wanted to see the cable and how it connects to the SKR 3 and the Raspberry Pi. * * * Serial connections are a lot harder to set up and get working reliably than USB ones; I can say that with experience. Please answer the questions above and let’s see what we can do about getting you up and running. I seriously suggest that you consider getting a Raspberrly Pi 4B+ as your host. The rPi 1 that you’re using may be the reason that you’re having the problems but you’ll find that things work better and run faster with the newer rPi. * * * > [@hfintegrale](#): > > I built a box for the printer to hold both the SKR3 and the Pi1, but the USB cable went around the outside, and if I accidentally bumped it, the Raspberry Pi would turn off. I hope I’ve been clearer so that you can help me in some way. I’ve seen people have this issue before a number of times and their solution to the issue, like you, is to go to a serial connection and the question that I always have to ask is: why don’t you design and print a bigger box that gives better protection to the USB cable? As I said, USB connections are a lot simpler with no need to make your own cables. You should also take a look at [Thingiverse.com](http://Thingiverse.com) and see if somebody has had the same issue and have designed an enclosure that you can print and use. ---
**Author:** ![hcet14](https://avatars.discourse-cdn.com/v4/letter/h/ecd19e/32.png) [@hcet14](https://klipper.discourse.group/u/hcet14)\ **Post date:** [July 2, 2025, 8:08pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/6 "2025-07-02T20:08:10Z")
> [@mykepredko](#): > > Please answer all questions as completely as possible Sorry, I didn’t read the post from hfintegrale carefully. My bad! @hfintegrale Did you try to swap PA10 and PA9" Meaning swapping TX and RX when your RPi is working? > [@hfintegrale](#): > > the Raspberry Pi would turn off. How old is your RPi 1? Could be, there is a hardware defect on that board or with the power supply. ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 9:07pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/7 "2025-07-02T21:07:19Z")
My fault, the Raspberry is a Pi 2 from 2014. I just found out now that I took the picture. ![IMG_20250702_223506](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/0/3/0318675faee98d13fc13de76470fd7aaef060fec.jpeg) ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 9:07pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/8 "2025-07-02T21:07:52Z")
![IMG_20250702_223707](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/d/3/d3c15ed78a0121ed9a6d9215b4ef2c5559e87a0b.jpeg) ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 9:08pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/9 "2025-07-02T21:08:24Z")
![IMG_20250702_223437](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/0/8/08f98a94e120b980fea50ca186154fb1a7bb724d.jpeg) ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 9:08pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/10 "2025-07-02T21:08:55Z")
![IMG_20250702_223715](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/0/c/0c22da4ba61af365e265e18ed05ac561dee5dc54.jpeg) ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 9:09pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/11 "2025-07-02T21:09:30Z")
![IMG_20250702_223756](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/f/8/f81504893561e997aeb46f54132261b2f61881fd.jpeg) ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 9:10pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/12 "2025-07-02T21:10:01Z")
![IMG_20250702_223718](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/a/5/a5707b0361c68694542cb2c022b6eb4ba4f7fe16.jpeg) ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 2, 2025, 9:10pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/13 "2025-07-02T21:10:55Z")
![IMG_20250702_224122](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/f/2/f2314ec7a018e035a8021e1b7df9998179a7c6e9.jpeg) ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [July 3, 2025, 1:43am UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/14 "2025-07-03T01:43:55Z")
That’s really helpful - that’s what I’m looking for. Now, it looks like you’re powering the Raspberry Pi 2 from the BTT SKR 3 board. Is that correct? If it is, could you disconnect the 5V line to the rPi and power it from a Raspberry Pi power supply? Leave the other three lines (GND, RX & TX) in place. I am wondering about the draw the Raspberry Pi 2 (and WiFi adapter) has on the SKR 3 5V power supply. If it’s too great, then it may cause the MCU on SKR 3 to brown out, leading to the problems that you’re having. ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 16, 2025, 3:27pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/15 "2025-07-16T15:27:15Z")
Sorry for the delay, I was traveling. MIKEPREDKO, I did as you suggested: I disconnected the 5V pin coming from the SKR3 and used an external power supply, but the result didn’t change. ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [July 17, 2025, 2:28am UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/16 "2025-07-17T02:28:42Z")
Could you go through the process you’re using to get the connection between the rPi and the SKR 3? Also, the reference that you’re using as well. Apologies, it’s been two weeks since I last heard from you and I’m trying to remember everything we were discussing. If I remember correctly, we’re: - Confident that your Firmware image has been built correctly - Reasonably confident that you have a good connection between your rPi and SKR 3 What I believe I haven’t seen is the process you’re following and what you get when you execute: ```auto ls /dev/serial/by-id ``` ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 24, 2025, 10:41am UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/17 "2025-07-24T10:41:37Z")
Problem solved, with the help of a good mentor who found that the uart port had to be enabled with two strings to be added to the config.xtx file ![Screenshot_2025-07-24-12-38-00-304_com.google.android.googlequicksearchbox](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/0/5/05ff329824f147b69858df46a58bdbb325d17131.jpeg) ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 24, 2025, 10:58am UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/18 "2025-07-24T10:58:19Z")
thank you so much to everyone who tried to help me out ---
**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\ **Post date:** [July 24, 2025, 11:22am UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/19 "2025-07-24T11:22:33Z")
Thank you for sharing the solution. ---
**Author:** ![hcet14](https://avatars.discourse-cdn.com/v4/letter/h/ecd19e/32.png) [@hcet14](https://klipper.discourse.group/u/hcet14)\ **Post date:** [July 24, 2025, 6:36pm UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/20 "2025-07-24T18:36:51Z")
Could you post the text from the picture above? I guess it’s Italian. Go\*gle translator might help 😉 ---
**Author:** ![hfintegrale](https://avatars.discourse-cdn.com/v4/letter/h/71e660/32.png) [@hfintegrale](https://klipper.discourse.group/u/hfintegrale)\ **Post date:** [July 25, 2025, 7:02am UTC](https://klipper.discourse.group/t/problems-with-usart1/24093/21 "2025-07-25T07:02:13Z")
You are right UART Connection Setup on Raspberry Pi The Raspberry Pi 2B+ has a UART interface (GPIO 14 TXD and GPIO 15 RXD) that needs to be enabled and configured. - Disable serial console and enable serial port: - Connect to your Raspberry Pi via SSH. - Edit the config.txt file: sudo nano /boot/config.txt - Add the following lines to the end of the file: enable\_uart=1 dtoverlay=miniuart-bt - Look for any line that might disable the serial port and comment it out or remove it: - Save the file (Ctrl+O, Enter, Ctrl+X). - Edit the cmdline.txt file: sudo nano /boot/cmdline.txt - Locate the text console=serial0,115200 or console=ttyAMA0,115200 and remove it completely. Your line should look something like this: console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles - Save the file (Ctrl+O, Enter, Ctrl+X). - Reboot your Raspberry Pi: sudo reboot [Next page](https://klipper.discourse.group/t/problems-with-usart1/24093.md?page=2)