<p>I also have an ender 3 pro that I added a bl touch to. I set mine up with removing the z limit switch and connecting the bl touch using those pins along with the z probe pins. You need to verify which board you have (probably a v4.2.2) and which cpu is on your board,mine was STM32F103 RET6 CPU there are some using a different model. I was never able to get marlin to build and work with the bl touch, however I was able to flash <a href="https://github.com/zisismaras/ender_3_4.2.2_firmware" rel="nofollow noreferrer">https://github.com/zisismaras/ender_3_4.2.2_firmware</a> which worked fine. A 4.2.2 board with the RET6 cpu is required. You / someone could do a config side by side and figure out which flag(s) you are missing in your configuration or you could just flash whichever probe grid you are comfortable with and use these auto builds.</p>

CC BY-SA 4.0
2024-02-16T00:40:31.600Z
I've got the RET6, luckily, so this should work for me. I'll give it a shot in the next couple of days; if this pre-built image works then I'll figure out what's missing in my config. Thanks!
ttshaw1
CC BY-SA 4.0
2024-02-17T01:34:30.450Z
Well, the 5x5 auto probe firmware didn't work. I verified that Creality's firmware is working as expected; I'll have to see if I can get them to fork over their source code so I can figure out what they're doing differently
ttshaw1
CC BY-SA 4.0
2024-02-15T22:29:20.833Z
2024-02-15T22:29:20.833Z
Gwazh
<p>I think this is an issue with Marlin v2.1.2.2, which I was trying to use. <a href="https://github.com/MarlinFirmware/Marlin/issues/26809" rel="nofollow noreferrer">https://github.com/MarlinFirmware/Marlin/issues/26809</a> this issue points to another bug with probing. My issue is different, but downgrading to 2.1.1 solved it.</p>

CC BY-SA 4.0
2024-03-12T04:48:30.507Z
2024-03-12T04:48:30.507Z
ttshaw1
<p>I have an Ender 3 Pro, board version 4.2.2, and a CR Touch with 5 pin connector. I also removed the z-axis endstop connector at the endstop.</p>
<p>I've been building and flashing Marlin 2.1.2.2, but I haven't found a configuration that makes the CRTouch work as expected. Typically, during auto homing, the machine will ignore the probe triggering and drive Z into the bed either 100% of the time or most of the time. I didn't take detailed enough notes to know for sure.</p>
<p>As a test case, I tried following along with <a href="https://3dprinting.stackexchange.com/questions/19617/configuring-marlin-2-x-with-ender-3-4-2-2-and-bltouch">this answer</a> exactly and still had the same problem. Configuration changes from the Marlin Ender 3 Pro default:</p>
<ul>
<li>Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN commented out</li>
<li>USE_PROBE_FOR_Z_HOMING uncommented</li>
<li>Z_MIN_PROBE_PIN uncommented and set to PB1</li>
<li>BLTOUCH uncommented</li>
<li>NOZZLE_TO_PROBE_OFFSET set to { -44, -9, -0.9 } (here I differ slightly from the { -44, -9, 0 } in the answer)</li>
<li>AUTO_BED_LEVELING_UBL uncommented</li>
<li>ENABLE_LEVELING_AFTER_G28 uncommented</li>
<li>Z_SAFE_HOMING uncommented (not in the answer, but in a comment)</li>
</ul>
<p>On my first boot after inserting the SD card with firmware:</p>
<ol>
<li>The probe deployed and retracted a couple of times, ending retracted with the red LED on</li>
<li>The machine seemingly flashed the firmware as it sat on a blue screen for a while</li>
<li>The CRTouch LED turned purple I think when flashing ended, though I can't tell from my video</li>
<li>When I got to the main menu, I started auto homing</li>
<li>X and Y axes worked as expected</li>
<li>For the Z axis, the probe centered on the build plate, deployed, and the LED turned blue</li>
<li>The probe started lowering, contacted the plate and retracted. The LED turned to blinking red, maybe steady red first. The Z motor kept driving down so I killed the power</li>
</ol>
<p>The extruder fan also made a loud buzzing noise that gradually grew quieter. In the past I've noticed the buzzing seemingly get quieter when the probe is deployed or retracted.</p>
<p>Anyone know what could be causing this, or how to troubleshoot it? Creality's firmware works as expected, so it's not a hardware problem. I was thinking maybe PB1 is wrong for the Ender 3 Pro, but from what I see online I gather it's the same mainboard between both printers.</p>

CC BY-SA 4.0
2024-02-15T13:44:46.460Z
You modified the hardware in a degree that it does not match the original hardware expected by the firmware. Of course you need a custom firmware now. The Z-Probe isn't a simple toggle though.
Trish
CC BY-SA 4.0
2024-02-15T16:54:39.953Z
@Trish I'm not expecting stock Marlin to work. My question is what I need to play around with in my configuration to get the expected behavior, as miming someone with presumably the same hardware configuration isn't working
ttshaw1
CC BY-SA 4.0
2024-02-15T17:08:12.563Z
Ahhh! So the question is basically "How do I properly enable the BL touch in Marlin 2.1.2.2 using the ender3 chip? We might need to know the exact model of sensor.
Trish
CC BY-SA 4.0
2024-02-16T00:39:17.693Z
@Trish It's a CR Touch, not a BL Touch. I'm not aware of there being more than one model of the CR Touch
ttshaw1
<creality-ender-3><marlin><bltouch><z-probe><crtouch>
What do I need to configure to get Marlin to run an Ender 3 Pro with CR Touch?
ttshaw1
# What do I need to configure to get Marlin to run an Ender 3 Pro with CR Touch?

(Asked by: username_0 on 2024-02-15)

I have an Ender 3 Pro, board version 4.2.2, and a CR Touch with 5 pin connector. I also removed the z-axis endstop connector at the endstop.

I've been building and flashing Marlin 2.1.2.2, but I haven't found a configuration that makes the CRTouch work as expected. Typically, during auto homing, the machine will ignore the probe triggering and drive Z into the bed either 100% of the time or most of the time. I didn't take detailed enough notes to know for sure.

As a test case, I tried following along with [this answer](https://3dprinting.stackexchange.com/questions/19617/configuring-marlin-2-x-with-ender-3-4-2-2-and-bltouch) exactly and still had the same problem. Configuration changes from the Marlin Ender 3 Pro default:

* Z\_MIN\_PROBE\_USES\_Z\_MIN\_ENDSTOP\_PIN commented out
* USE\_PROBE\_FOR\_Z\_HOMING uncommented
* Z\_MIN\_PROBE\_PIN uncommented and set to PB1
* BLTOUCH uncommented
* NOZZLE\_TO\_PROBE\_OFFSET set to { -44, -9, -0.9 } (here I differ slightly from the { -44, -9, 0 } in the answer)
* AUTO\_BED\_LEVELING\_UBL uncommented
* ENABLE\_LEVELING\_AFTER\_G28 uncommented
* Z\_SAFE\_HOMING uncommented (not in the answer, but in a comment)

On my first boot after inserting the SD card with firmware:

1. The probe deployed and retracted a couple of times, ending retracted with the red LED on
2. The machine seemingly flashed the firmware as it sat on a blue screen for a while
3. The CRTouch LED turned purple I think when flashing ended, though I can't tell from my video
4. When I got to the main menu, I started auto homing
5. X and Y axes worked as expected
6. For the Z axis, the probe centered on the build plate, deployed, and the LED turned blue
7. The probe started lowering, contacted the plate and retracted. The LED turned to blinking red, maybe steady red first. The Z motor kept driving down so I killed the power

The extruder fan also made a loud buzzing noise that gradually grew quieter. In the past I've noticed the buzzing seemingly get quieter when the probe is deployed or retracted.

Anyone know what could be causing this, or how to troubleshoot it? Creality's firmware works as expected, so it's not a hardware problem. I was thinking maybe PB1 is wrong for the Ender 3 Pro, but from what I see online I gather it's the same mainboard between both printers.

**Tags:** creality-ender-3, marlin, bltouch, z-probe, crtouch
> **Comments:**
> **username_1**: You modified the hardware in a degree that it does not match the original hardware expected by the firmware. Of course you need a custom firmware now. The Z-Probe isn't a simple toggle though.  
> **username_0**: @Trish I'm not expecting stock Marlin to work. My question is what I need to play around with in my configuration to get the expected behavior, as miming someone with presumably the same hardware configuration isn't working  
> **username_1**: Ahhh! So the question is basically "How do I properly enable the BL touch in Marlin 2.1.2.2 using the ender3 chip? We might need to know the exact model of sensor.  
> **username_0**: @Trish It's a CR Touch, not a BL Touch. I'm not aware of there being more than one model of the CR Touch  

---

## 2 answers

### Answer by username_0 on 2024-03-12. Score: 2 | Accepted answer

I think this is an issue with Marlin v2.1.2.2, which I was trying to use. <https://github.com/MarlinFirmware/Marlin/issues/26809> this issue points to another bug with probing. My issue is different, but downgrading to 2.1.1 solved it.


---

### Answer by username_2 on 2024-02-15. Score: 0

I also have an ender 3 pro that I added a bl touch to. I set mine up with removing the z limit switch and connecting the bl touch using those pins along with the z probe pins. You need to verify which board you have (probably a v4.2.2) and which cpu is on your board,mine was STM32F103 RET6 CPU there are some using a different model. I was never able to get marlin to build and work with the bl touch, however I was able to flash <https://github.com/zisismaras/ender_3_4.2.2_firmware> which worked fine. A 4.2.2 board with the RET6 cpu is required. You / someone could do a config side by side and figure out which flag(s) you are missing in your configuration or you could just flash whichever probe grid you are comfortable with and use these auto builds.

> **Comments:**
> **username_0**: I've got the RET6, luckily, so this should work for me. I'll give it a shot in the next couple of days; if this pre-built image works then I'll figure out what's missing in my config. Thanks!  
> **username_0**: Well, the 5x5 auto probe firmware didn't work. I verified that Creality's firmware is working as expected; I'll have to see if I can get them to fork over their source code so I can figure out what they're doing differently  

---

