# Ender 3 Max + Cr touch: want to make sure I won't break my printer

**URL:** <https://klipper.discourse.group/t/ender-3-max-cr-touch-want-to-make-sure-i-wont-break-my-printer/2520>\
**Category:** General Discussion\
**Created:** [April 6, 2022, 1:51pm UTC](https://klipper.discourse.group/t/ender-3-max-cr-touch-want-to-make-sure-i-wont-break-my-printer/2520 "2022-04-06T13:51:27Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![cribbageSTARSHIP](https://avatars.discourse-cdn.com/v4/letter/c/ba9def/32.png) [@cribbageSTARSHIP](https://klipper.discourse.group/u/cribbageSTARSHIP)\
**Post date:** [April 6, 2022, 1:51pm UTC](https://klipper.discourse.group/t/ender-3-max-cr-touch-want-to-make-sure-i-wont-break-my-printer/2520/1 "2022-04-06T13:51:27Z")

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I’d like to switch over from the stock Creality firmware to klipper. As I’m already using Octoprint on my Pi4-8gb I’ll be using octoklipper. I self host spaghetti detective so I have to use octoprint regardless.

I have a few questions to make sure I won’t cause irreparable damage when I first start up the printer.

Printer is an Ender 3 max with a 4.2.2 board, and the 522K STM32F103 RET6 CPU.

Q1: My CR-Touch is already hooked up and I know my z-offset. I’ll be measuring the X and Y offsets via a manual measurement. The concern I have is if I dont have the code correct my printhead will smash into the build plate when I turn on my printer and try to Home it. As well, how do I verify the pins mentioned in the example below to that of my board?

```
[bltouch]
sensor_pin: ^PB1
control_pin: PB0
x_offset: -42
y_offset: -10
z_offset: 0

[safe_z_home] 
home_xy_position: 150,150 # Change coordinates to the center of your print bed
z_hop: 10 # Move up 10mm z_hop_speed: 5

```

I know the ^ means pullup resistor, but below there is a ^! and I dont know what the ! means.

Q2: The screen. I have a 12864 LCD screen and would like to use it. After a lot of searching I was able to find a post somewhere that said the following:

```
Try using the klipper code below. I'm pretty sure it's for the Max.

[display]
lcd_type: st7920
cs_pin: EXP1_7
sclk_pin: EXP1_6
sid_pin: EXP1_8
encoder_pins: ^EXP1_5, ^EXP1_3
click_pin: ^!EXP1_2

[output_pin beeper]
pin: EXP1_1
 
Make sure you have an aliases section in your config to alias the EXP port

```

I’m used to alias usage from Bash alias’. I’m just unclear as to how to make it work for klipper configs.

I found a marlin page for the [STM32F1 boards](https://github.com/MarlinFirmware/Marlin/blob/2.0.x/Marlin/src/pins/stm32f1/pins_CREALITY_V4.h) but I’m not sure if its the right board as it states v4.h. I found [This pic](https://images.app.goo.gl/3hCjXEdjonVX6m2p9) where it shows some pinouts for the display on the board but I’ve no idea where to put them in the config.

Any assistance would be appreciated. Thank you

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**Author:** ![jakep\_82](https://avatars.discourse-cdn.com/v4/letter/j/ea666f/32.png) [@jakep\_82](https://klipper.discourse.group/u/jakep_82)\
**Post date:** [April 6, 2022, 3:32pm UTC](https://klipper.discourse.group/t/ender-3-max-cr-touch-want-to-make-sure-i-wont-break-my-printer/2520/2 "2022-04-06T15:32:10Z")

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For homing, it doesn’t matter what the initial z\_offset is set to, the printer will stop when the bltouch triggers. Once the printer is homed, you need to run `PROBE_CALIBRATE` to establish the correct z\_offset. See the documentation [here](https://www.klipper3d.org/Probe_Calibrate.html#calibrating-probe-z-offset).

Using a ! inverts the logic, so trigger low or trigger high.

Klipper provides a sample config for the Ender 3 Max that has all the pins you need pre-configured, including the display. See [this link](https://github.com/Klipper3d/klipper/blob/master/config/printer-creality-ender3max-2021.cfg).

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**Author:** ![cribbageSTARSHIP](https://avatars.discourse-cdn.com/v4/letter/c/ba9def/32.png) [@cribbageSTARSHIP](https://klipper.discourse.group/u/cribbageSTARSHIP)\
**Post date:** [April 6, 2022, 4:28pm UTC](https://klipper.discourse.group/t/ender-3-max-cr-touch-want-to-make-sure-i-wont-break-my-printer/2520/3 "2022-04-06T16:28:51Z")

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Thank you so much. This was very informative.

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**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:** [May 7, 2024, 6:26am UTC](https://klipper.discourse.group/t/ender-3-max-cr-touch-want-to-make-sure-i-wont-break-my-printer/2520/4 "2024-05-07T06:26:56Z")

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