# When connecting to UART, TX1 resetting itself...
**URL:** https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861
**Category:** Jetson TX1
**Created:** [July 23, 2017, 9:42am UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861 "2017-07-23T09:42:37Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@sems](https://forums.developer.nvidia.com/u/sems)
#### Post date: [July 23, 2017, 9:42am UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861/1 "2017-07-23T09:42:37Z")
I saw some tutorials about serial connections and level shifting with uart(at jetsonhacks). But i have a problem about TX1 and UART channels. When i wired all system it reset itself and the screen is going to black forever. I just want to communicate arduino and jetson tx1 using with the uart.
So i guess the problem is the arduino TX/RX output voltages, so i already ordered some [https://www.sparkfun.com/products/12009](https://www.sparkfun.com/products/12009) but i did a voltage divider circuit for reduce the voltage to 3.3v. The Jetson is set to 3.3v not 1.8v so i thought it’s going to be working, but no it’s still not working but there’s a good sign after making voltage divider there were no black screen or resetting itself. Just still can’t see on lsusb or can’t reach with minicom,cat commads etc.
I hope you guys can help me about this i’ve been working on this about 2 days … I have no hope … The only hope is you guys.
Thank you.
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### Author:  [@linuxdev](https://forums.developer.nvidia.com/u/linuxdev)
#### Post date: [July 23, 2017, 8:56pm UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861/2 "2017-07-23T20:56:42Z")
Which connector are you using for which UART? I wouldn’t think the Jetson would have any boot error on the screen unless it didn’t boot…if you use the J21 connector, then you’re connected to the serial console and any activity will halt U-Boot to wait for console commands.
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### Author:  [@sems](https://forums.developer.nvidia.com/u/sems)
#### Post date: [July 24, 2017, 6:35pm UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861/3 "2017-07-24T18:35:45Z")
> [@](#):
>
> Which connector are you using for which UART? I wouldn’t think the Jetson would have any boot error on the screen unless it didn’t boot…if you use the J21 connector, then you’re connected to the serial console and any activity will halt U-Boot to wait for console commands.
Yeah I need the conenct arduino board with J21. How can i accomplish that ?
Thank you, by the way I’m getting understand this board right now.
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### Author:  [@linuxdev](https://forums.developer.nvidia.com/u/linuxdev)
#### Post date: [July 24, 2017, 8:07pm UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861/4 "2017-07-24T20:07:34Z")
If you use the UART at J17 (“/dev/ttyTHS2”, also 3.3V logic level) it would be easier. The only qualification is that it goes to the camera module, so you’d probably want to remove that (it mounts with two screws). To disable J21 from serial console is easy once Linux boots, but this isn’t the issue…the issue is that disabling it in U-Boot is more difficult. You would probably have to adjust the U-Boot source and flash the changed boot loader. Are you using the camera?
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### Author:  [@sems](https://forums.developer.nvidia.com/u/sems)
#### Post date: [July 24, 2017, 10:33pm UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861/5 "2017-07-24T22:33:09Z")
> [@](#):
>
> If you use the UART at J17 (“/dev/ttyTHS2”, also 3.3V logic level) it would be easier. The only qualification is that it goes to the camera module, so you’d probably want to remove that (it mounts with two screws). To disable J21 from serial console is easy once Linux boots, but this isn’t the issue…the issue is that disabling it in U-Boot is more difficult. You would probably have to adjust the U-Boot source and flash the changed boot loader. Are you using the camera?
Actually, yes i’m going to use at least 2 camera on Jetson TX1. I want to run SCServo (Dynamixel Smart Servos) on TX1-TX2 while using camera. But these servos communicates on UART so i need some UARTS on TX1-TX2 to control SCservos.
Some information about dynamixel servos : [http://www.instructables.com/id/How-to-drive-Dynamixel-AX-12A-servos-with-a-Raspbe/](http://www.instructables.com/id/How-to-drive-Dynamixel-AX-12A-servos-with-a-Raspbe/)
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### Author:  [@linuxdev](https://forums.developer.nvidia.com/u/linuxdev)
#### Post date: [July 24, 2017, 10:55pm UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861/6 "2017-07-24T22:55:52Z")
The onboard sample camera mezzanine is the one connected to J17. If you don’t use that particular connector you can still use J17.
You have another option you may not have considered: You can get a USB serial UART. Mostly the FTDI serial USB UARTs are supported out of the box, and you can get versions directly supporting your I/O voltage, e.g., 1.8V or 3.3V.
You will need to find a way to not interact with the TX/RX line of the J21 serial UART during initial boot unless you go into the boot loader and figure out how to disable serial console there (I have not done this, someone else may have already done so and have advice). If you want to disable serial console once past the boot loader stage just edit “/boot/extlinux/extlinux.conf”. Just remove this part from the APPEND key/value’s value:
```auto
console=ttyS0,115200n8
```
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### Author:  [@TomNVIDIA](https://forums.developer.nvidia.com/u/TomNVIDIA)
#### Post date: [October 18, 2021, 6:59pm UTC](https://forums.developer.nvidia.com/t/when-connecting-to-uart-tx1-resetting-itself/51861/7 "2021-10-18T18:59:11Z")