TMS320F28035: failed to enter main() with TMS/GPIO36 and TDI/GPIO35 pulled low

Aki Li

My customer used the JTAG signals( TCK, TDI, TMS and TDO) also with GPIO functions, due to the IO amount limitation. They used TMS/GPIO36 and TDI/GPIO35 as input signals in their application. However, they found if the voltage at GPIO35 and GPIO36 was low during the power up, the firmware seemed not be able to enter main(). Could you please help check the possible reason? Thank you.

over 3 years ago

0 Peter Luong over 3 years ago

TI__Mastermind 23441 points

Hi Aki,

Our JTAG expert is out of office this week. Please expect a reply by beginning of next week

Regards,

Peter

0 Aki Li over 3 years ago in reply to Peter Luong

TI__Genius 10115 points

Hi Peter,

Thank you for the help. Could you please help follow up this question? Customer waited for our feedback to solve this urgent issue.

0 Marlyn Rosales Castaneda20 over 3 years ago in reply to Aki Li

TI__Mastermind 27050 points

Hi Aki,

Do you know what the status of the TRST signal is and the JTAGDEBUG register? I'd like to make sure that the GPIOs are indeed configured for GPIO mode.

Best Regards,

Marlyn

0 Aki Li over 3 years ago in reply to Marlyn Rosales Castaneda20

TI__Genius 10115 points

Marlyn,

Customer confirmed the the TRST pin was pulled down by 10k resistor.

0 Marlyn Rosales Castaneda20 over 3 years ago in reply to Aki Li

TI__Mastermind 27050 points

Aki,

A stronger pull down might be needed. If its possible, could TRST be tied to ground just for debugging purposes to see if a stronger pull down will do the trick.

Best Regards,

Marlyn

C2000™︎ microcontrollers

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TMS320F28035: failed to enter main() with TMS/GPIO36 and TDI/GPIO35 pulled low