IWR6843ISK: Uniflash not able to connect to serial port although I went through all recommended troubleshooting steps.

Jan Jessen

Part Number: IWR6843ISK
Other Parts Discussed in Thread: UNIFLASH, IWR6843, , IWRL6432

Tool/software:

I just got the IWR6832ISK and want to run the out-of-the-box example on Windows 10. For this I need to flash the board using Uniflash.

I installed Uniflash as well as the CP210x_VCP_Windows drivers and configured the DIP-Switches to flashing mode (1-0-1-1-0-0). Both COM-Ports appear in Windows Device Manager (Enhanced as COM3, Standard as COM4), however if I try to flash it, I get an output like this.

[9/15/2025, 2:04:45 PM] [INFO] Cortex_R4_0: Initialization complete.

[9/15/2025, 2:04:45 PM] [INFO] Cortex_R4_0: Flashing process starting...

[9/15/2025, 2:04:45 PM] [INFO] Cortex_R4_0: Connecting to COM Port COM3...

[9/15/2025, 2:04:45 PM] [INFO] Cortex_R4_0: Reset connection to device

[9/15/2025, 2:04:45 PM] [ERROR] Cortex_R4_0: Serial port COM3 specified does not exist, is already open, or permission is denied!!

[9/15/2025, 2:04:45 PM] [ERROR] Cortex_R4_0: !! Aborting operation!!

[9/15/2025, 2:04:45 PM] [ERROR] Cortex_R4_0: Not able to connect to serial port. Recheck COM port selected and/or permissions.

[9/15/2025, 2:04:45 PM] [INFO] Cortex_R4_0: Flashing instance clean-up initiated...

[9/15/2025, 2:04:45 PM] [INFO] Cortex_R4_0: Instance deinitialized!

The file I'm trying to flash is C:\ti\rdt\radar_toolbox_3_20_00_04\source\ti\examples\Out_Of_Box_Demo\prebuilt_binaries\out_of_box_6843_isk.bin

Troubleshooting steps I tried:

Uninstalled and reinstalled the CP210x drivers. Also tried the Windows Universal and the VCP_Windows variant.
Tried to initialize the flashing with both COM3 or COM4 selected
Reboot to clear potential other process blocking the comPort
Tried selecting IWR6843ISK as well as pure IWR6843 in Uniflash
Tried running Uniflash with Administrator privileges
Verified with procexp that no other process is accessing the COM-Port
Tried a different USB-Cable
Physically moved all DIP-switches to ensure they register in the proper orientation
Toggling the NRST-switch multiple times, also directly before a flashing attempt
Tried all permutations of plugging in the USB and then starting up Uniflash or vice versa
Switched to a different Machine, went through all steps clean again, same problem.
Verified I have the correct revision of IWR6832ISK board (678A on the board)