J-link not find device(Info: Could not measure total IR len. TDO is constant high.)

[steven]

Dear all: Now,i have issue ,i can't fund device.(i have sure the hardware is OK) i think it is program overwrite the J-TAG register(TDO)? but i may not sure. have any experience about this error?

i try run J-Link commander to clear ,but

J-Link> r Info: Could not measure total IR len. TDO is constant high. Reset delay: 0 ms Reset type UNKNOWN: ??? Info: Could not measure total IR len. TDO is constant high. J-Link>r

****** Error: TCK (pin 9) low, but should be high. Please check target hardware. Reset delay: 0 ms Reset type UNKNOWN: ???

and i exe nrfjprog --recover to

it get C:\Users\steven>nrfjprog --recover Applying pin reset if debugger is not active. System off disabled until pin reset or power on reset is done. Halting device. ERROR: Cannot connect to the nRF51 device.

the nRFgo studio is also not found any device .(In the boot of the moment, nRFgo maybe detect the device) read back protected or not found device.

[Shane]

Thanks Paul! Your solution worked for me this morning. Not sure why this happens. Yesterday, everything was downloading fine but this morning I got the TDO error. I had not made any changes to the JLink settings.

It seems these settings somehow get switched around w/o the user doing it. I am running on a VM, though, so the JLink is being connected/reconnected through Parallels. Not sure why that would matter.