Problem with OS X and cu.usbmodem

[Marius Heil]

Hello,

not strictly an nrf question, but I am having trouble communicationg with the developer dongles under OS X. I am using screen to connect to my terminal and the input and output seem to work at first, but as soon as I copy and paste a longer command, it appends "USB" to that string. Don't know where it comes from. If my string gets longer, it will crash the serial port. Are there any specific drivers for the USB to Serial Bridge that I could install?

Thanks, Marius

[RK]

That's the most bizarre issue I've heard yet .. randomly appending 'USB' to something. The developer dongles support a standard USB CDC device for which the driver in OSX is one of the most mature around, I've run all sorts of different CDC devices over it and never had an issue. There used to be odd issues with FTDI based devices, but even those appear now to be fixed. So no you should need no special driver.

'screen' is a bit old however and not updated in a long time, and not perfect for straight serial communication. I use CoolTerm (freeware.the-meiers.org) which, despite being written by a guy who claims he's not a programmer, and in RealBasic too, is stable, has all the features I've ever needed and 'just works'. I also have something called 'SerialTools' which I think came free from the mac app store but mostly use CoolTerm. I've used that with serial devices from 300 to 115200 baud, with and without flow control, on nordic chips (really segger chips as they provide the serial interface), TI chips, Atmel chips and FTDI chips and had no problems.

Perhaps if you try a different serial program you'll have better success, either way I'd recommend giving that a go and seeing if it helps.

[David Smoot]

+1 to RK's answer and I will add one other serial tool I sometimes use on OS X. Cornflakes

[Marius Heil]

Thanks, the problem is that I want to communicate with the dongle with Java, I was using this library: code.google.com/.../ which works absolutely fine on Linux and Windows but seems to have a Problem on OS X 10.10. When I send long commands (longer than 70 chars it seems to send USB for whatever reason). I tested it on OS X 10.9 and did not have that problem.

[RK]

Ok so what has that got to do with 'screen' then? Do you have the problem with screen or with the java library or with both of them? The whole issue really doesn't make a lot of sense, what's appending 'USB' to the string, you're sending one string but the one on the other end ends 'USB' or 'USB' appears on the screen and is sent to the other end? If it's appearing on the screen, then it's more likely to have to do with the copy and paste operation.

Lots of us are using USB CDC devices as standard serial terminals with no issues, and at high speed, and for days on end (the ble sniffer just uses the serial port and transfers loads of data)

See if you can reproduce any issues with one of the serial programs just suggested.

[Marius Heil]

I'll try. So far I've reproduced the problem with the screen and the java library. minicom for example seemed to work. I've tested it on two OSX machines and had the same problem. My nrf51 implementation echos back the user input as soon as it receives something and apparently it is echoing back USB after a copy and paste operation,... After hours of testing, I've put this aside to be solved later.

A coworker had a problem with SUSE Linux once that stemmed from the serial port implementation in that it was often used as a modem. At some points, he got garbage on the uart port that was being sent to the nRF51 but he was able to swith it off. I am using the cu.usbmodem interface and I think it might be something similar, maybe OS X trying to access the serial port as a usb modem or sth. else...