Hello, I have a problem I have been unable to solve for more than a week. I have searched as best I know how to no avail.
Windows 10, Segger Studio, Mbed studio, nRF Connect, JLink apps
I have four identical nRF52 DK eval boards purchased in the last month or so. Out of the box I had trouble getting any of the boards to connect via USB and map the JLINK drive. I installed updated J-Link drivers and the problem seemed to go away. All good I thought.
I was able to perform some development with on one board eventually deciding to switch to the MBed development studio to take advantage of a sample program. To do so, I followed the instructions to switch the interface MCU over to the Mbed debugger. I put the board in boot by holding the reset button while powering on. BOOTLOADER mapped in explorer and I copied the new firmware file onto the interface MCU. At first, I saw MBED map in explorer as expected and moved on with my development. For unknown reasons, I began having connectivity issues. Most times, the MBED drive wouldn't map at all. When I attempted to put the board back in boot to switch back to JLINK, it didn't work. Specifically, BOOTLOADER will map in explorer but disappears 10-15 seconds later. Additionally, it will not accept a file copy during this time. Even though BOOTLOADER is no longer mapped, LED5 continues to blink as though boot is active.
Here is where it gets weird...I eventually gave up on the current board and moved on to one of the others. However, all of the additional boards show the same behavior of no JLINK drive and only mapping BOOTLOADER for 10-15s. At this point I assume some sort of PC/config/driver issues. Keep in mind these other three boards are unmodified from how I received them.
What I have done so far:
uninstalled everything: J-Link components and drivers, Segger Studio, Mbed Studio and nRF Connect.
Reinstalled the latest J-Link drivers (6.92)
Tried multiple different USB cords
Finally, exasperated, I plugged the boards into a separate win 10 machine that has had none of the J-Link or other IDE software installed on it. I assumed the boards should map in explorer as mass storage devices at least. Unfortunately, I saw the same behavior....no mapping in normal mode and BOOTLOADER mapping for 10-15 seconds before disappearing in boot mode.
I have no idea what could be going on or what to try next.
Any ideas would be greatly appreciated.
