LAUNCHXL-CC2650: Cannot open serial port with Launchpad

Sean Reihani

Part Number: LAUNCHXL-CC2650
Other Parts Discussed in Thread: CC2650, , FLASH-PROGRAMMER, UNIFLASH, CCSTUDIO

I flashed the UART echo example to a CC2650 Launchpad, but I cannot establish a serial connection using PuTTY. Based on the printf statements and Board_LED1, I know that main() is executed. In PuTTY, I set the serial settings to match those specified in the example's ReadMe, i.e.

Baud-rate:    9600
    Data bits:       8
    Stop bits:       1
    Parity:       None
    Flow Control: None

But when I try to open the terminal, I get an error saying "Unable to open connection to COM3  Unable to open serial port" 
(In device manager, COM3 shows up as XDS Class Application/User UART (COM3)

over 5 years ago

0 YiKai Chen over 5 years ago

Guru 735685 points

Make sure you don’t have CCS opened at the same time when you test UART echo example.

0 Ryan Brown1 over 5 years ago

TI__Guru**** 218357 points

Hi Sean,

The behavior you've described indicates an issue with the XDS110 as compared to operation of the firmware. If this or the backchannel UART communication lines were faulty then the PuTTY terminal would open but remain blank. However, you were able to use the XDS110 to program the CC2650 so the situation is quite abnormal. What are your PuTTy and system OS versions? Have you tried a different terminal program? Try restarting your PC and power-cycling the LAUNCHXL-CC2650.

Regards,
Ryan

0 Sean Reihani over 5 years ago in reply to Ryan Brown1

Prodigy 220 points

Hi Ryan,

My PuTTY release number appears to be 0.72, and my OS is Windows 10 Home, build 19041.508. I tried using RealTerm, and it could not even detect the COM port (yet again, it is present in device manager). Restarting and power cycling does not seem to help.

One detail that may be helpful: when I first tried flashing the board I received the message "Texas Instruments XDS110 USB Debug Probe/Cortex_M3_0 : Target must be connected before loading program." To fix this, I went to Project -> Properties -> Debug -> Auto Run and Launch and enabled "Connect to the target on debugger startup"

Thanks,

Sean

0 Sean Reihani over 5 years ago in reply to YiKai Chen

Prodigy 220 points

Hi YiKai,

I tried this, but I could still not establish a connection

0 Ryan Brown1 over 5 years ago in reply to Sean Reihani

TI__Guru**** 218357 points

Hi Sean,

The versions are fine, thank you for providing that information. This still appears to be a problem with the XDS110. What version of CCSTUDIO are you using and have you tried loading the program with UNIFLASH or FLASH-PROGRAMMER? https://software-dl.ti.com/ccs/esd/documents/xdsdebugprobes/emu_xds110.html

Regards,
Ryan

0 Sean Reihani over 5 years ago in reply to Ryan Brown1

Prodigy 220 points

Hi Ryan,

I tried restarting my computer, and strangely enough now it seems to be working.

Thanks!

-Sean

0 YiKai Chen over 5 years ago in reply to Sean Reihani

Guru 735685 points

Yes, restarting desktop sometimes help for such issue.

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LAUNCHXL-CC2650: Cannot open serial port with Launchpad