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Jetson Nano RoboClaw Control

Posted: Mon Feb 03, 2020 12:07 pm
by scubadiv3r
Hello!
I'm currently attempting to control a chain of 2x30 roboclaws using my Jetson Nano over UART communications. Only having one in the bus isn't a problem, but once you add more to the bus it starts sending packets super slow and it leads to erratic motor control. I've gotten it working with a bunch chained together on Raspberry Pi using this tutorial just fine: https://resources.basicmicro.com/packet ... erry-pi-3/


I'm really struggling to figure out why it won't work on the Jetson Nano, there were some settings that needed to be configured on the Pi to do this, but I haven't found a way to do so on the Jetson, if it's even necessary: https://resources.basicmicro.com/config ... rial-port/


Anyone work with a Jetson Nano before? Thanks a ton

Re: Jetson Nano RoboClaw Control

Posted: Tue Feb 04, 2020 10:25 am
by Basicmicro Support
After talking with you on the phone yesterday I think we determined it was how the Jetson is using the timeout argument in the Open function in the python library. In the Open function we set a packet timeout of 1 second and a byte timeout(the char timeout) to .01seconds. The char timeout appears to always have priority on RPi and Windows systems.

After testing on the Jetson, we determined the packet timeout was triggering. This was set to a default of 1 second since it had no effect under previous testing. However on the Jetson this should be set much lower. Equal to the char timeout is probably appropriate(eg 0.01seconds).

Re: Jetson Nano RoboClaw Control

Posted: Thu Feb 06, 2020 2:46 pm
by scubadiv3r
There were two things wrong with our Jetson Nano: the mA on a pin of a Jetson Nano was like, 1mA, way lower than a Pi or an Arduino. The Roboclaw UART line needs between 5-25mA, so we had barely enough to control one Roboclaw, but once we added more to the bus it just didn't have enough amps. Additionally we did need to change the timeout in the library to .01. We used a USB-TTYL converter to boost the amps of the UART line and it worked. Thanks a ton!

Re: Jetson Nano RoboClaw Control

Posted: Thu Feb 27, 2020 5:25 am
by haj
Hey there, I am currently also trying to get my Jetson Nano to control 2 RoboClaws (Multi-Unit) over UART.

What was your setup like, @scubadiv3r? Did you have an external power source connected to each of the roboclaws or did you try to power them all over the jetson nano and was that the reason you didn't have enough current or was it that only the UART communication would require a higher current than 1mA?

I'm powering my roboclaws over an external battery and I am just wondering if I should setup the communication with the jetson nano via the J41 RXD and TXD pins or if I also should go for the USB-TTL solution.

Thanks in advance!

Re: Jetson Nano RoboClaw Control

Posted: Mon Mar 09, 2020 9:28 am
by scubadiv3r
They were all powered externally from a known good power source, we've also tried powering the Jetson via barrel jack vs pins with no real change in results

Re: Jetson Nano RoboClaw Control

Posted: Mon Mar 09, 2020 10:46 am
by Basicmicro Support
Input power to the Jetson wont determine the output power of a single I/O pin. So how you power the board as long as it is reasonable for the power draw shouldnt matter. Teh above post mentions the Jetson has a drive current of 1ma. That is very low. In those cases you may need a buffer chip to convert the 1ma signal into something with a bit more oomph(usually 25ma).

Re: Jetson Nano RoboClaw Control

Posted: Fri Sep 25, 2020 8:13 pm
by astronav
Sorry to bring this back alive, but there are very few resources out there for this! I am using a Jetson NX, but the boards are about the same (except my UART is coming out of ttyTHS0). I have verified my UART connection with a simple serial test. I have also configured my Roboclaw to use packetized serial at 115200 baud. I made the modification with regards to the timeout in the previous comments as well. I am not sure if the low current issue is my problem, but do you have information about how you boosted the power with a USB-TTL cable? That is the last thing I can think to try. Thanks!

Re: Jetson Nano RoboClaw Control

Posted: Mon Sep 28, 2020 8:17 am
by Basicmicro Support
What is the Serial signal from the Nanos, Voltage amplitude. Eg 3.3v? If it is 1.8v then you will need to add a buffer/level converter between the Nano and the Roboclaw(eg from the Nano TX to Roboclaw S1 pin). Roboclaw can only ready logic down to around 2v. 1.8v signals will not be "seen".

Re: Jetson Nano RoboClaw Control

Posted: Sun Oct 04, 2020 7:17 am
by astronav
The Jetson NX has all signals at 3.3v. I did test with a level logic converter in the mix brining it up to 5v. Through multiple iterations of testing, I have gotten it working without adding the converter in the middle but am having inconsistent behavior.

On the bench, I am using a 2x15A. I am now able to consistently communicate with it just doing simple python commands to get status and version. But when I switch over to the 2x7A that I am using, I am not getting valid responses. I have restored default settings on the controller and both the 2x15A and 2x7A are programmed to be the same. I am not sure what the difference is and why it is inconsistent at times. Any thoughts?

Re: Jetson Nano RoboClaw Control

Posted: Mon Oct 05, 2020 9:03 am
by Basicmicro Support
Electrically there is no difference in the logic circuits of the 2x7A and 2x15A. Perhaps there is something wrong with the 2x7A? Have you confirmed both are on the same firmware version?