CCS/TM4C123GH6PZ: XDS110 Error -1170 @ 0x0 unable to access DAP

Hi Ralph.

First, in answer to your question, No I didn't change the API.

Second, I've downloaded and installed UniFlash. I run it and select the TM4C123GH6PZ device and XDS110 debugger. I click the Start button and then go to the DebugPortUnlock section at the bottom of the window, select Tiva Class and press and hold the reset button down while I turn on power. Then release the reset button and click on Unlock. I get a Please Wait ... window and then a red Error! Module closed window pops up. Meanwhile, the window that says Please Wait ... is saying Executing startup scripts: CORTEX_M4_0. Am I doing something wrong?

Actually, I've just gone over that Settings and Utilities page more carefully and realise I didn't set the Clock frequency to 16 MHz (my crystal). I've just entered the clock frequency and tried again. After clicking on Unlock nothing seems to happen. What should happen? What is the purpose of the Finish Unlock button? When should I press that?

Hello Halo,

You should get prompts throughout the process:

Alternatively you can follow the process on page 24 of our JTAG User's Guide: http://www.ti.com/lit/an/spma075/spma075.pdf

Hi Ralph. Thanks for the help. Following the instructions in spma075 I have managed to reset the device and can execute the program upto main() again. I am a bit wary of going past this and executing the SysCtlClockSet() function until I can find some reason why it might have gone wrong in the first place. Do you have any suggestions?

int main(void)
{
  unsigned long ulLoop;

  for ( ulLoop = 1000; ulLoop > 0; ulLoop-- ) {
    ;
  }
  // Enable main clock
  SysCtlClockSet( SYSCTL_SYSDIV_25 | SYSCTL_USE_PLL |
                  SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ );
  // Enable peripheral clock
  //SysCtlPeripheralClockGating( 0xff );  // Only required for peripherals that need clocking
  //
  if ( SysCtlPeripheralPresent( SYSCTL_PERIPH_GPIOA ) ) {
    // Enable the relevant GPIO Module
    SysCtlPeripheralEnable( SYSCTL_PERIPH_GPIOA );
    // Loop until ready
    while ( !SysCtlPeripheralReady( SYSCTL_PERIPH_GPIOA ) ) {
    }
    //
    //PortA_Init();
  }
  //
  if ( SysCtlPeripheralPresent( SYSCTL_PERIPH_GPIOB ) ) {
    // Enable the relevant GPIO Module
    SysCtlPeripheralEnable( SYSCTL_PERIPH_GPIOB );
    // Loop until ready
    while ( !SysCtlPeripheralReady( SYSCTL_PERIPH_GPIOB ) ) {
    }
    //
    //PortB_Init();
  }
  //
  if ( SysCtlPeripheralPresent( SYSCTL_PERIPH_GPIOC ) ) {
    // Enable the relevant GPIO Module
    SysCtlPeripheralEnable( SYSCTL_PERIPH_GPIOC );
    // Loop until ready
    while ( !SysCtlPeripheralReady( SYSCTL_PERIPH_GPIOC ) ) {
    }
    //
    //PortC_Init();
  }

Hello Halo,

I am not sure either as I tried the full block you posted on my LaunchPad and it works fine.

Are you sure the crystal on your BOM has been correctly populated? That could cause an issue. Especially if the code bricks the board again.

You may want to check your programmer settings too just to be sure on that end.

Hi Ralph. I'm pretty sure the Xtal is the right way around. It's a 4-pad xtal and pad 1 is clearly labelled by having an odd trapezoidal shape rather than being rectangular, but I'll check up on that. I'm not sure what you mean by 'check your programmer'; what aspects of it should I check? I have altered the SysCtlClockSet() argument so that the main oscillator runs off the internal 16 MHz PIOSC and that works fine. I think the oscillator source is only going to matter when I try to get the USB to work; I believe USB needs a fairly accurate clock. Harry.