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.

[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...