On Mac OSX (OSX 10.10) I have J-Link (V10) working with TI's CodeComposerStudio (CCS 7.3) and the Tiva launchpad TM4C123GH6PM (Tiva) - no problems there. I can run and debug the Tiva thru CCS or run standalone (powered through the J-Link).

By using the workaround in this Segger-forum post, I can get my simple blinky/RTT program to compile in CCS, and per the terminal output I see, can seemingly connect from a Mac Terminal to this running code via JLinkEXE and/or JLinkRTTClient but I cannot see any RTT output.

I have tried various combinations of the Tiva running under CCS debug and/or simply standalone (powered by the J-Link).

I will be happy to post any number of dumps for the various JLinkEXE and JLinkClient configurations I have tried, but first I thought I should verify some fundamentals:

1. Am I missing some compiler setting and/or fundamental concept? (why didn't my simple RTT program compile right out of the box? that is, why did I have to use the above-linked work around posted for SystemView?)
2. Is RTT supposed to work under OSX when the Tiva is flashed via the J-Link from the CCS IDE?

Thanks for any help,
JJ

Nino,
Thanks for responding.
In case there are any Mac OSX/Tiva/CodeComposerStudio(CCS) people following, especially anyone new to the world of SEGGER, here is what finally worked for me.

On the Mac, there is no JLinkRTTViewer; these notes are centered around using JLinkExe and JLinkRTTClient. I also punched through to JLinkRTTLogger but won't say much more about that here.

I got the JLinkRTTClient to work with and without the CCS Debugger running. The auto-location of the control block did not work at all for me - for example, within JLinkExe, I tried variations of the

J-Link> exec SetRTTSearchRanges 0x20000000 0x800

command, but could never make it work.

In hindsight, I spent too much time thinking i just had to get the address *close* since the documentation suggests that the controlBlock address is *usually* found automatically (JLink scanning for the id in certain memory spaces).
No.
Within my setup anyway, close didn't matter at all; 1 byte off wasn't close enough.

Nor could I ever get the SetRTTSearchRanges command to work.

Finally I focused on exactly specifying the address of the control block.
For anyone reading these notes, it can easily be found a few ways:

• The map file: CCS has it as (.common:_SEGGER_RTT)
  
• Looking at address of _SEGGER_RTT within debugger. Note that _SEGGER_RTT is instantiated within SEGGER_RTT.c
  
• Or more perversely you could even loop through memory yourself, searching for the initialized string "SEGGER RTT" in memory, as long as you make sure SEGGER_RTT_Init() has been called previously.
  

In any case, once you have the exact address, you can enter it within JLinkExe. For me, the control block was at 0x20000400.

J-Link> exec SetRTTAddr 0x20000400

Note that JLink provides no feedback about whether or not your JLink 'exec command' is good or bad, ie if it thinks there is actually an initialized control block at your address. It only complains on a parsing error.

So, in summary:

1) Ascertain the address of _SEGGER_RTT variable (the RTT control block).

2) In CCS, flash the Tiva via the JLink

3) In an OSX terminal shell, run the JLinkExe program, and connect. For example,
JLinkExe -device TM4C123GH6PM -speed 4000 -if SWD
_________ here's a shot from my screen _____________

OSX:/Applications/SEGGER/JLink_V622d> ./JLinkExe -device TM4C123GH6PM -speed 4000 -if SWD
SEGGER J-Link Commander V6.22d (Compiled Dec 14 2017 18:33:52)
DLL version V6.22d, compiled Dec 14 2017 18:33:43

Connecting to J-Link via USB...O.K.
Firmware: J-Link V10 compiled Dec 12 2017 16:37:47
Hardware version: V10.10
S/N: 260105980
License(s): FlashBP, GDB
OEM: SEGGER-EDU
VTref = 3.296V

Type "connect" to establish a target connection, '?' for help
J-Link>connect
Device "TM4C123GH6PM" selected.

Connecting to target via SWD
Found SW-DP with ID 0x2BA01477
Scanning AP map to find all available APs
AP[1]: Stopped AP scan as end of AP map has been reached
AP[0]: AHB-AP (IDR: 0x24770011)
Iterating through AP map to find AHB-AP to use
AP[0]: Core found
AP[0]: AHB-AP ROM base: 0xE00FF000
CPUID register: 0x410FC241. Implementer code: 0x41 (ARM)
Found Cortex-M4 r0p1, Little endian.
FPUnit: 6 code (BP) slots and 2 literal slots
CoreSight components:
ROMTbl[0] @ E00FF000
ROMTbl[0][0]: E000E000, CID: B105E00D, PID: 000BB00C SCS-M7
ROMTbl[0][1]: E0001000, CID: B105E00D, PID: 003BB002 DWT
ROMTbl[0][2]: E0002000, CID: B105E00D, PID: 002BB003 FPB
ROMTbl[0][3]: E0000000, CID: B105E00D, PID: 003BB001 ITM
ROMTbl[0][4]: E0040000, CID: B105900D, PID: 000BB9A1 TPIU
ROMTbl[0][5]: E0041000, CID: B105900D, PID: 000BB925 ETM
Cortex-M4 identified.
J-Link>

4) Run the exec command from within JLinkExe
J-Link> exec SetRTTAddr 0x20000400

5) In another OSX terminal shell, start the JLinkRTTClient (no command line args)
you should see your output from RTT writes in your code. For example:

SEGGER_RTT_Init();
// .... other code
SEGGER_RTT_WriteString(0, "blahblah WriteString(0,...) blahblah \n");
SEGGER_RTT_TerminalOut(1, "blah blah TerminalOut(1,..) blahblah \n");

Note that variations on (4) above can be tried while OSX Terminal processes (3) and (5) continue running... the JLinkRTTClient output will start and stop accordingly.

Cheers,
JJ