<p>The <a href="https://reprap.org/mediawiki/images/2/24/RRD-RUMBA_SCHEMATICS.png" rel="nofollow noreferrer" title="RUMBA schematic">RUMBA schematic</a> is available on the <a href="https://reprap.org/wiki/RUMBA" rel="nofollow noreferrer">RUMBA wiki</a>.  </p>

<blockquote>
  <p><a href="https://reprap.org/mediawiki/images/2/24/RRD-RUMBA_SCHEMATICS.png" rel="nofollow noreferrer" title="RUMBA schematic"><img src="https://reprap.org/mediawiki/images/2/24/RRD-RUMBA_SCHEMATICS.png" alt="RUMBA schematic" title="RUMBA schematic"></a></p>
</blockquote>

<p>From the schematic, I see that UART3 (with +5V logic levels, not RS232) is presented on the EXP3 connector.  I don't know if Marlin firmware can be controlled through a UART other than UART0, which is converted to USB through an FDDI chip.  The Arduino bootloader is not expecting another UART, so you may still need to program it through the USB port (and UART0).</p>

CC BY-SA 4.0
2019-06-06T07:28:18.483Z
Did you mean FTDI (i.e. [FT232RL](https://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf)) and not FDDI? Also, the RUMBA appears to use a 16U2 to implement USB, not an FTDI.
Greenonline
CC BY-SA 4.0
2019-06-06T11:11:57.597Z
Yes to both.  I didn't spend enough time with the schematic.  Thank you.
cmm
CC BY-SA 4.0
2019-06-07T02:52:31.330Z
Sorry i didn't put in there that i wanted to use uart for my tmc2208 drivers sorry about that... But are you saying that the chip only expects uart from the usb does that mean i cant use uart for my drivers?
lolatron
CC BY-SA 4.0
2019-06-07T03:20:54.237Z
You can use those pins as you wish, if they are otherwise free.  In Arduino, it will be Serial3.begin(baud_rate) to start it.  The other port will work as it normally works.
cmm
CC BY-SA 4.0
2019-06-07T03:43:10.750Z
how do i setup the pins.h to tell the Arduino that those pins will be used for uart connections for the stepper drivers?
lolatron
CC BY-SA 4.0
2019-06-07T10:57:44.807Z
If they are using the Arduino libraries and have not changed things, all you should need to do is Serial3.begin(baud_rate_you_need);
cmm
CC BY-SA 4.0
2019-06-07T12:11:08.607Z
Of you are using the new motor drivers for real-time motion control, you may face significant challenges adapting the firmware.  This discussion should probably be moved to another forum, as comments are not intended for ongoing discussion.
cmm
CC BY-SA 4.0
2019-06-05T20:16:35.337Z
2019-06-06T07:34:27.637Z
2019-06-06T07:34:27.637Z
cmm
<p>I have been looking in the Marlin firmware for about an hour or two now to find what pins I should use for UART for my tmc2208 drivers and I have come up with nothing.</p>

<p>Does anyone know what they are or how to assign them? BTW, I am using the regular version of the RUMBA board not the RUMBA+ version.</p>

<p>For somereason i didn't put that i want to control my stepper motor drivers through uart they are tmc2208</p>

CC BY-SA 4.0
2019-06-05T22:41:01.583Z
Why do you need the UART? What are you trying to achieve? Do you want to reflash the firmware?
Greenonline
CC BY-SA 4.0
2019-06-06T07:57:50.763Z
Is it a genuine RUMBA or a Chinese clone. I have both RUMBA boards and found that the Chinese clones cut corners and as such some things don't work. E.g. the exposed USB pin header on the RUMBA+ is totally unusable when you properly connect it, the board stops working...
0scar
CC BY-SA 4.0
2019-06-07T02:56:08.400Z
sorry i didn't put that i wanted to use uart for my tmc2208 drivers my bad.
lolatron
<marlin><troubleshooting><electronics><stepper-driver>
What pins do I use for UART control on a RUMBA board for tmc2208?
lolatron
# What pins do I use for UART control on a RUMBA board for tmc2208?

(Asked by: username_0 on 2019-06-05)

I have been looking in the Marlin firmware for about an hour or two now to find what pins I should use for UART for my tmc2208 drivers and I have come up with nothing.

Does anyone know what they are or how to assign them? BTW, I am using the regular version of the RUMBA board not the RUMBA+ version.

For somereason i didn't put that i want to control my stepper motor drivers through uart they are tmc2208

**Tags:** marlin, troubleshooting, electronics, stepper-driver
> **Comments:**
> **username_1**: Why do you need the UART? What are you trying to achieve? Do you want to reflash the firmware?  
> **username_2**: Is it a genuine RUMBA or a Chinese clone. I have both RUMBA boards and found that the Chinese clones cut corners and as such some things don't work. E.g. the exposed USB pin header on the RUMBA+ is totally unusable when you properly connect it, the board stops working...  
> **username_0**: sorry i didn't put that i wanted to use uart for my tmc2208 drivers my bad.  

---

## 1 answers

### Answer by username_3 on 2019-06-05. Score: 3 | Accepted answer

The [RUMBA schematic](https://reprap.org/mediawiki/images/2/24/RRD-RUMBA_SCHEMATICS.png "RUMBA schematic") is available on the [RUMBA wiki](https://reprap.org/wiki/RUMBA).

> [![RUMBA schematic](https://reprap.org/mediawiki/images/2/24/RRD-RUMBA_SCHEMATICS.png "RUMBA schematic")](https://reprap.org/mediawiki/images/2/24/RRD-RUMBA_SCHEMATICS.png "RUMBA schematic")

From the schematic, I see that UART3 (with +5V logic levels, not RS232) is presented on the EXP3 connector. I don't know if Marlin firmware can be controlled through a UART other than UART0, which is converted to USB through an FDDI chip. The Arduino bootloader is not expecting another UART, so you may still need to program it through the USB port (and UART0).

> **Comments:**
> **username_1**: Did you mean FTDI (i.e. [FT232RL](https://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf)) and not FDDI? Also, the RUMBA appears to use a 16U2 to implement USB, not an FTDI.  
> **username_3**: Yes to both.  I didn't spend enough time with the schematic.  Thank you.  
> **username_0**: Sorry i didn't put in there that i wanted to use uart for my tmc2208 drivers sorry about that... But are you saying that the chip only expects uart from the usb does that mean i cant use uart for my drivers?  
> **username_3**: You can use those pins as you wish, if they are otherwise free.  In Arduino, it will be Serial3.begin(baud_rate) to start it.  The other port will work as it normally works.  
> **username_0**: how do i setup the pins.h to tell the Arduino that those pins will be used for uart connections for the stepper drivers?  
> **username_3**: If they are using the Arduino libraries and have not changed things, all you should need to do is Serial3.begin(baud_rate_you_need);  
> **username_3**: Of you are using the new motor drivers for real-time motion control, you may face significant challenges adapting the firmware.  This discussion should probably be moved to another forum, as comments are not intended for ongoing discussion.  

---

