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.

[Paul]

This is what I did to solve the problem:

Go to Cortex Jlink/Jtrace target driver setup.

In Debug Tab: Make sure the Port is set to SW, NOT JTAG. (Sometime copy/paste project will get this setting switch to JTAG).

In Flash Download Tab: Make sure nRF51xxx is selected in the programming algorithm.

After these two step. the TDO high problem is gone.

[Shane]

Yup, verified it this morning. Running WinXP on Parallels (8.0.18615) on OSX and relinking the JLink to the WinXP VM USB ->sometimes<- causes the Port to flick back to JTag within the debug/use panel w/o me doing anything to the setting.

Not sure what Parallels is doing, but a little annoying.

[Paul]

Must be the Jlink driver somehow decided to reset/change its setting automatically. Could be a setting somewhere (regedit?) to "lock" the setting, or disable the "auto mode".

[Sébastien Despont]

Great answer. Thanks

[Lionel Sacks]

Just to add to the noise ... I also had this for the first time just now, although this was not the first time I'd copied a project from one folder to another!

Not to mention that it's a 'shame' that Keil mVision can't use environment variables...