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How use JTAG port as normal GPIO in C2000

yanzhen fu
Genius 4005 points


HI , maybethis question is not realy question. !

but.uestion is : if JATG port as GPIO, how can i debug program ? or I just can use scI download program?

is there other way to swich JATG and GPIO. ? example:  when I download program, it is JTAG. other time it is normal GPIO.?

  • 0
    Genius 4005 points

    I search some post, it  said " JTATDEBUG register bit JTAGDIS can configurate .  that opertaion need TRST pin high voltage. but , if JTAGDIS set '1'. that mean JATG disable . that is very dangerous. because if do it , cpu can not download program with JTAG.

    what should I do?

  • 0 in reply to yanzhen fu
    TI__Guru 57255 points

    Hello,

    Your understanding is correct. 

    On many C2000 devices you can configure most JTAG signals to be GPIO pins.  However, once programmed you won't be able to debug via JTAG anymore.  You'll instead need to use SCI or some other communication port to assist your debugging efforts.

    Note that it is possible to re-enable the JTAG port (once you've programmed the FLASH on your device to use the JTAG pins as GPIO pins) by changing to device's boot mode to 'Wait mode'.  After a power cycle, the JTAG pins will again be able to connect to your C2000 MCU.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Genius 4005 points

    hi: Brett

    thank you to reply this post. but "changing to device's boot mode to 'Wait mode'  , how operate can I do? "after a power cycle". what is mean?

    because I want use "clockin" function of pin. but it is in JTAG port . very urgent need to know these way. thanks !

  • 0 in reply to yanzhen fu
    TI__Guru 57255 points

    Hi,

    The boot mode can be changed by editing the default state of the 'boot pins' (via pull-up or pull-down resistors).

    For most Piccolo devices, the boot pins are GPIO34 and GPIO37(TDO).  However, the best place to get this information is from your device's datasheet.  In the datasheet you will also find which combination of pull-ups/pull-downs on these pins will correspond to which boot mode.

    If you are using Piccolo (such as the F28035) please note that GPIO19 can also be used for XCLKIN.  However, since you are talking about using GPIO38 for this I suppose that you are already using GPIO19 for some other purpose.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Genius 4005 points

    hi Brett:

    thanks alot for your reply.

    I use 28027F as MCU . when I confugurated  PWM,SCI. SPI. I2C . I find just one GPIO can used.  so I want use JTAG ports as normal GPIO, but I fraid if I use it .I will lose debug function.!