I got the exactly same issue as yours, and it has not been solved yet.
if I type 'hwinfo' command in J-link commander, i noticed that 'target power is disabled'.
Also, as other threads mentioned, i typed command 'speed 8000' and 'rx 0' , but got 'arm core is not halted', I think this is the reason why jtag couldn't get control of the core.
However, i don't know how to 'halt' the core.
Posted By dwills on 29 May 2008 6:30 PM
Here are the JTAG messages:
J-Link>r
Reset delay: 50 ms
Reset type NORMAL: Using RESET pin, halting CPU after Reset
Info: TotalIRLen = 3, IRPrint = 0x01
Info: Resetting target using RESET pin
WARNING: RESET (pin 15) high, but should be low. Please check target hardware.
Info: Halting CPU core
Info: Resetting target using RESET pin
WARNING: RESET (pin 15) high, but should be low. Please check target hardware.
Info: Halting CPU core
Info: Resetting target using BP@0.
****** Error: Too few devices on the JTAG bus. IRPos: 0, TotalIRLen: 3
J-Link>