I am using Eclipse Kelpler SD2 and GNU ARM 4.7 tool chain, plus GNU ARM Eclipse Plugin

and after download code into CM0
I got the warning

"The connected emulator does not support serial wire output (SWO)


My setup environment

1. Eclipse IDE for C/C++ Developers
Version: Kepler Service Release 2

2. GNU ARM tool chain 4.7

3. GNU ARM Eclipse plug-in

4. J-link V4.90d


What could be the cause of the problem?


=============== J-Link GDB Server Log ========================

SEGGER J-Link GDB Server V4.90d GUI Version

JLinkARM.dll V4.90d (DLL compiled Aug 29 2014 14:49:16)

-----GDB Server start settings-----
GDBInit file: none
GDB Server Listening port: 2331
SWO raw output listening port: 2332
Terminal I/O port: 2333
Accept remote connection: localhost only
Generate logfile: off
Verify download: off
Init regs on start: on
Silent mode: off
Single run mode: off
Target connection timeout: 5 sec.
------J-Link related settings------
J-Link Host interface: USB
J-Link script: none
J-Link settings file: none
------Target related settings------
Target device: nRF51822_xxAA
Target interface: SWD
Target interface speed: 1000kHz
Target endian: little

Connecting to J-Link...
J-Link is connected.
Firmware: J-Link OB-SAM3U128 V1 compiled Aug 22 2014 17:25:44
Hardware: V1.00
S/N: 480209778
Checking target voltage...
Target voltage: 3.30 V
Listening on TCP/IP port 2331
Connecting to target...Connected to target
Waiting for GDB connection...Connected to 127.0.0.1
Reading all registers
Read 4 bytes @ address 0x00000000 (Data = 0x00000708)
Target interface speed set to 1000 kHz
Resetting target
Halting target CPU...
...Target halted (PC = 0x00000630)
R0 = FFFFFFFF, R1 = FFFFFFFF, R2 = FFFFFFFF, R3 = FFFFFFFF
R4 = FFFFFFFF, R5 = FFFFFFFF, R6 = FFFFFFFF, R7 = FFFFFFFF
R8 = FFFFFFFF, R9 = FFFFFFFF, R10= FFFFFFFF, R11= FFFFFFFF
R12= FFFFFFFF, R13= 00000708, MSP= 00000708, PSP= FFFFFFFC
R14(LR) = FFFFFFFF, R15(PC) = 00000630
XPSR C1000000, APSR C0000000, EPSR 01000000, IPSR 00000000
CFBP 00000000, CONTROL 00, FAULTMASK 00, BASEPRI 00, PRIMASK 00
Reading all registers
Select auto target interface speed (2000 kHz)
Flash breakpoints enabled
Semi-hosting enabled (VectorAddr = 0x08)
Semihosting I/O set to TELNET Client
SWO disabled succesfully.
GDB closed TCP/IP connection




======================== ==================

If I use Keil MDK evaluation version 4.7,
it did not give any warning, from log file it seems using JTAG instead of SW

Keil Debug Output:


JLink info:
------------
DLL: V4.90d, compiled Aug 29 2014 14:49:16
Firmware: J-Link OB-SAM3U128 V1 compiled Aug 22 2014 17:25:44
Hardware: V1.00
S/N : 480209778

* JLink Info: Found SWD-DP with ID 0x0BB11477
* JLink Info: Found Cortex-M0 r0p0, Little endian.
* JLink Info: FPUnit: 4 code (BP) slots and 0 literal slots
ROMTableAddr = 0xE00FF003

Target info:
------------
Device: nRF51822_xxAA
VTarget = 3.300V
State of Pins: TCK: 0, TDI: 0, TDO: 1, TMS: 1, TRES: 1, TRST: 1
Hardware-Breakpoints: 4
Software-Breakpoints: 8192
Watchpoints: 2
JTAG speed: 2000 kHz


=========================================


If I launch Jlink-GDB server with target interface JTAG, I will get error: Could not connect to target