# Can't connect BTT PI to CR200b motherboard through uart

**URL:** <https://klipper.discourse.group/t/cant-connect-btt-pi-to-cr200b-motherboard-through-uart/13517>\
**Category:** General Discussion\
**Created:** [January 26, 2024, 9:43am UTC](https://klipper.discourse.group/t/cant-connect-btt-pi-to-cr200b-motherboard-through-uart/13517 "2024-01-26T09:43:19Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yar](https://avatars.discourse-cdn.com/v4/letter/y/858c86/32.png) [@Yar](https://klipper.discourse.group/u/Yar)\
**Post date:** [January 26, 2024, 9:43am UTC](https://klipper.discourse.group/t/cant-connect-btt-pi-to-cr200b-motherboard-through-uart/13517/1 "2024-01-26T09:43:19Z")

</div>

### Basic Information:

Printer Model: Creality CR200-B  
 MCU / Printerboard: Creality V4.2.5, BTT PI 1.2  
 `klippy.log`

I already flashed printer mother board with klipper compiled for serial (on USART1 PA10/PA9),  
Changed console=display to console=serial in /boot/BoardEnv.txt .  
Changed [mcu] serial: /dev/ttyS0 also tried with /dev/ttyAMA0  
In printer cfg,  
Connected pins 3, 4 of diplay port to rx and tx gpio pins,  
Checked continuity of this pins to STM32 PA10/9 pins

Rechecked everything for many times, still nothing happens, getting can’t connect to Klipper error in mainsail.  
It worked fine through usb, but i intending to put pi inside printer chasis, so connecting through usb would require drilling hole, and sticking usb cable outside.

I see  
mcu ‘mcu’: Unable to open serial port: [Errno 2] could not open port /dev/serial/by-id/usb-1a86\_USB\_Serial-if00-port0: [Errno 2] No such file or directory: ‘/dev/serial/by-id/usb-1a86\_USB\_Serial-if00-port0’  
In klipper log, does that mean PI still trying to connect through USB ?

What else can i try ?

[klippy (4).log](https://klipper.discourse.group/uploads/short-url/pNyg5INFtqd7XBBLehtlEu6LiU4.log) (209.8 KB)

…

---

<div class="post-metadata">

**Author:** ![Yar](https://avatars.discourse-cdn.com/v4/letter/y/858c86/32.png) [@Yar](https://klipper.discourse.group/u/Yar)\
**Post date:** [January 26, 2024, 9:47am UTC](https://klipper.discourse.group/t/cant-connect-btt-pi-to-cr200b-motherboard-through-uart/13517/2 "2024-01-26T09:47:06Z")

</div>

I’m not able to add more than 1 attachemnt per reply, so for now will add only printer.cfg, please ask, if other files or photos would be helpful.  
[printer (1).cfg](https://klipper.discourse.group/uploads/short-url/crPlWI0GobNf1vPZGhMoiB42vBM.cfg) (6.0 KB)

---

<div class="post-metadata">

**Author:** ![Yar](https://avatars.discourse-cdn.com/v4/letter/y/858c86/32.png) [@Yar](https://klipper.discourse.group/u/Yar)\
**Post date:** [January 26, 2024, 10:18am UTC](https://klipper.discourse.group/t/cant-connect-btt-pi-to-cr200b-motherboard-through-uart/13517/3 "2024-01-26T10:18:10Z")

</div>

Just figured, i had been overriding mcu cobfig in printer cfg all that time. Delering second entry fixed the problem

 ![image](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/9/9c3fa7985c84e3f362956106620fb1a6a64b08b1.png)

---

<div class="post-metadata">

**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\
**Post date:** [February 25, 2024, 8:18pm UTC](https://klipper.discourse.group/t/cant-connect-btt-pi-to-cr200b-motherboard-through-uart/13517/4 "2024-02-25T20:18:14Z")

</div>

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.