Reading a serial device from Jetson TK1

I know that the serial port on the Jetson board is meant to be used as a serial console, but is it possible to use it to read data from a serial device instead?

What kind of a serial device? I think it should be possible but I also think that Jetson prints some “debug prints” there from the early boot and you can’t disable them. So those might complicate things.

There’s a separate UART on the expansion board and that might be more suitable for communicating with other devices. That is not an RS232 as the logic level is 1.8V (IIRC) so you may need some extra components there depending on what you want to connect there.

The device is a Keithley 2001 digital multimeter which I am using to monitor the Jetson power consumption… it provides a RS232 port for data readout, so it would be really interesting to be able to import readings about power usage in the running software…

I think it should be possible to stop the kernel from printing to serial and disable the shell from the serial port. Then you could use that in your application on Jetson. But still something would be printed from Jetson to the serial line during the Jetson boot.

I might be easier to connect something like this to Jetson instead:

I also use a serial UART/USB cable like what Kulve mentions. Then you still have the serial console and don’t have to mess with it. Serial UART USB cables more or less “just work”.

Going off of kulve’s post, the USB to serial converter “works” (with USB being plugged into jetson and DB-9 to your device). And by “works” i mean it sends messages, but there are random hiccups if you send a continuous stream of data. In my case, im using a roboteq motor controller on the ‘device’ end of the cable, and communication is made, messages are being sent, but not consistently, causing the motor’s to not have a continous motion.

I posted a question about this a while back and linuxdev gave some answers, but the hacked solution wouldnt work in my scenario.

It isn’t unusual to need to turn off any kind of sleep or suspend on the USB. The other thing is that some of the serial UART USB cables are quite different in quality of how they work. One I use which works well is this:

Using some form of “adapter” will never be as good as straight-through, but the speed ability under USB should be so far beyond the DB-9 serial port that when it works right it won’t have any noticeable glitches. Testing of course is the only way to know if it will work under the specific circumstances.

Hello, I manage to do it simply by running this command before using the serial port :

sudo stop ttyS0

So the serial console is still enable at startup if needed.