TMS320F280049: How does the C28x detect a connected debugger?

Robin Liebfried

Part Number: TMS320F280049

Hi everyone,

How does the F280049 does detect the debugger (in my case an XDS110) physically?
In the technical reference for the F280049, I can find the register CPU_SYS_REGS.RESC.DCON (3.14.4.26), which provides this information, but I need to know how this bit is set. What GPIO or pin determines whether DCON is 1 or 0?

Thank you in advance and best regards,
Robin

over 5 years ago

0 KARTHIKEYAN RAJAMANICKAM over 5 years ago

TI__Genius 11645 points

This not decided by any external GPIO's directly.

Once the emulator attempts connection with the target, using some of the internal state-machines inside, this bit get's set.

0 Robin Liebfried over 5 years ago in reply to KARTHIKEYAN RAJAMANICKAM

Prodigy 115 points

Hello Karthik,

thank you for the quick response.
I am asking because I want to "emulate" a disconnected debugger, even though it is actually connected. I am using an ISO7241 between the XDS110 and the F280049. Therefore unplugging the debugger will lead to an undefined state at the TDI, TDO, and TMS pins. I hoped that I can get the disconnected signal by manipulating one pin.

So now I have to make sure, that the signals mentioned above are pulled high at the XDS side of the ISO7241?

Best regars,

Robin

0 KARTHIKEYAN RAJAMANICKAM over 5 years ago in reply to Robin Liebfried

TI__Genius 11645 points

That should suffice I guess. Let me reconfirm with our CCS/Driver experts on this once.

0 Vivek Singh over 5 years ago in reply to KARTHIKEYAN RAJAMANICKAM

TI__Guru** 115271 points

Robin,

In other post I have mentioned how you can emulate standalone boot with debugger connected. You can try that to debug the code.

Regards,

Vivek Singh

0 Robin Liebfried over 5 years ago in reply to KARTHIKEYAN RAJAMANICKAM

Prodigy 115 points

Hi Karthik,

I tried it with the pull-ups. It is not working at the moment. I will do some other tests to make sure it is not a software issue. I'll post the results here.

Best regards,
Robin

0 Edward Fewell over 5 years ago in reply to Robin Liebfried

TI__Intellectual 2515 points

The DCON or debug connected bit is set when the debug probe scans a specific value into a JTAG register of the F280049. In CCS though, the probe does not fully disconnect debug until you follow this sequence:

1) From Run menu select Free Run

2) Then Disconnect.

At that point, debug functionality will be disconnected from the C28x core.

0 KARTHIKEYAN RAJAMANICKAM over 5 years ago in reply to Edward Fewell

TI__Genius 11645 points

Thanks for confirming that Edward

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TMS320F280049: How does the C28x detect a connected debugger?