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TM4c123gh6pm UART0 and UART1 problem

Sriram Venkatachalam
Prodigy 30 points
Other Parts Discussed in Thread: TM4C123GH6PM, LMFLASHPROGRAMMER

Hi guys, I am using TM4c123gh6pm arm processor. I am using both uart0 and uart1 (uart1 along with interupts) in my project. I face a problem when I include the following line in my code;

GPIO_PORTC_PCTL_R = GPIO_PCTL_PC5_U1TX | GPIO_PCTL_PC4_U1RX;

The following error occurs whenever I type the above mentioned line in my code ( I am pasting the error msgs here for ur reference);

"CORTEX_M4_0: Can't Run Target CPU
CORTEX_M4_0: Error
CORTEX_M4_0: Unable to determine target status after 20 attempts
CORTEX_M4_0: Failed to remove the debug state from the target before disconnecting. There may still be breakpoint op-codes embedded in program memory. It is recommended that you reset the emulator before you connect and reload your program before you continue debugging."

 I had to use lmflashprogrammer whenever this error pops up. I know that the UART1 functionality would completely fail if I remove this line. The reason why I say that this particular line causes this error is because, no errors occured when I removed this line (all though the UART1 didn't work when I removed this line). Guys pls help.  

     

  • 0
    Guru 26105 points

    Hi,

    Modify your setting as this:

    GPIO_PORTC_PCTL_R |= (GPIO_PCTL_PC5_U1TX | GPIO_PCTL_PC4_U1RX);

    This is because PCTL of port C is by default started with value 0x1 (JTAG enabled), and this is changed by your expression. See page 685 of user manual for more info. 

    Petrei

  • 0 in reply to Petrei
    Guru 47900 points

    Poster Petrei's first identified - then solved - your "murder of JTAG."

    Yet - use of Direct Register instead of far simpler & tested & example-laden Driver Library is not, "best/brightest" means of development.

    Driver Lib. will speed, ease & enhance your development efforts - Direct Register (as you've found) - not so much.

  • 0 in reply to Petrei
    Prodigy 30 points

    Hi petrei,

    Thanks a lot. That was very a very silly mistake. Thanks once again.  

  • 0 in reply to cb1
    Prodigy 30 points

    Thanks cb1, I will definitely take ur advice.