TM4C129ENCPDT: Create custom bootloader for EK-TM4C129EXL

Hi all,

First of all let me allow to thanks for all that the hard work what you are doing for us under the PANDEMIC.
I am opening this thread because of the following reason. We are developing SW for TM4C129ENCPDT and for MSP432E401Y, and we run into some problems.
I would like to create a custom bootloader for a EK-TM4C129EXL.
In a development stage i took the boot_emac_flash example from the TivaWare_C_Series-2.2.0.295. 
I modified the bl_config.h. Uncommented the #define BL_INIT_FN_HOOK and the #define BL_CHECK_UPDATE_FN_HOOK. 
I wrote my own functions.

First i just wanted to make sure these functions are running so used a simple blink function.

void MyInitFunc(void){


            volatile uint32_t ui32Loop;

           //
           // Enable the GPIO port that is used for the on-board LED.
           //
           ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);

           //
           // Check if the peripheral access is enabled.
           //
           while(!ROM_SysCtlPeripheralReady(SYSCTL_PERIPH_GPION))
           {
           }

           //
           // Enable the GPIO pin for the LED (PN0).  Set the direction as output, and
           // enable the GPIO pin for digital function.
           //
           ROM_GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE, GPIO_PIN_0);

           //
           // Loop forever.
           //

           volatile  uint16_t xi;

           for( xi = 0; xi <100; xi++)
           {
               //
               // Turn on the LED.
               //
               ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, GPIO_PIN_0);

               //
               // Delay for a bit.
               //
               for(ui32Loop = 0; ui32Loop < 500000; ui32Loop++)
               {
               }

               //
               // Turn off the LED.
               //
               ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, 0x0);

               //
               // Delay for a bit.
               //
               for(ui32Loop = 0; ui32Loop < 500000; ui32Loop++)
               {
               }
        }

}

In the first trials nothing happend. After that i tried to debug it but is a bit tricky and i realized that the bootloader stuck.
I tried some changes (used volatile) and the prev. inserted code can run in debug mode.

But when i try to run the device in standalone mode no blinking, noting happening. The device was fully ereased prev. 

More or less i was happy because in debug mode it worked. So made the second step in my tiny project.

Here is what i modified in the bl_config.h:

• #define BL_CHECK_UPDATE_FN_HOOK DetermineBootSeq
• #define BL_INIT_FN_HOOK MyStartFunc

I wrote the custom BL_CHECK_UPDATE_FN_HOOK to check the content of the eeprom at a specified address.

uint32_t DetermineBootSeq(void){

    uint32_t ui32EEPROMInit;
    uint32_t ReadCustomBLFlags[2];
    //
    // Enable the EEPROM module.
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_EEPROM0);
    //
    // Wait for the EEPROM module to be ready.
    //
    while (!SysCtlPeripheralReady(SYSCTL_PERIPH_EEPROM0))
    {
    }
    //
    // Wait for the EEPROM Initialization to complete
    //
    ui32EEPROMInit = EEPROMInit();
    //
    // Check if the EEPROM Initialization returned an error
    // and inform the application
    //
    if (ui32EEPROMInit != EEPROM_INIT_OK)
    {
        while (1)
        {
        }
    }
    //  //Get the EEPROMSize +
    //READ some data FROM THE LAST 2 WORD OF the EEPROM
    //
    //uint32_t EepromMaxSize = EEPROMSizeGet();
    EEPROMRead(ReadCustomBLFlags, BL_CUSTOME_FLAGS_ADDRESS,
               sizeof(ReadCustomBLFlags));

    if (ReadCustomBLFlags[BL_ALWAYS_RUN_ADDRESS] == BL_ALWAYS_RUN)
    {
        return (1);
    }
    else
    {
        if (ReadCustomBLFlags[BL_UPDATE_STATUS_ADDRESS] == BL_UPDATE_END)
        {
            //
            // See if the first location is 0xfffffffff or something that does not
            // look like a stack pointer, or if the second location is 0xffffffff or
            // something that does not look like a reset vector.
            //
          volatile  uint32_t *pui32App;
            pui32App = (uint32_t*) APP_START_ADDRESS;
            if ((pui32App[0] == 0xffffffff)
                    || ((pui32App[0] & 0xfff00000) != 0x20000000)
                    || (pui32App[1] == 0xffffffff)
                    || ((pui32App[1] & 0xfff00001) != 0x00000001))
            {
                return (1);
            }
            //a valid image exists
            // and no update is needed.
            // return(0)
            return (0);
        }
        else
        {
                        //If the update not complated run the bootloader for update

            return (1);
        }
    }

}

Also wrote the BL_INIT_FN_HOOK :

void MyStartFunc(void){


            volatile uint32_t ui32Loop;

           //
           // Enable the GPIO port that is used for the on-board LED.
           //
           ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);

           //
           // Check if the peripheral access is enabled.
           //
           while(!ROM_SysCtlPeripheralReady(SYSCTL_PERIPH_GPION))
           {
           }

           //
           // Enable the GPIO pin for the LED (PN0).  Set the direction as output, and
           // enable the GPIO pin for digital function.
           //
           ROM_GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE, GPIO_PIN_0);

           //
           // Loop forever.
           //

           volatile  uint32_t xi;

           for( xi = 0; xi <100; xi++)
           {
               //
               // Turn on the LED.
               //
               ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, GPIO_PIN_0);

               //
               // Delay for a bit.
               //
               for(ui32Loop = 0; ui32Loop < 500000; ui32Loop++)
               {
               }

               //
               // Turn off the LED.
               //
               ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, 0x0);

               //
               // Delay for a bit.
               //
               for(ui32Loop = 0; ui32Loop < 500000; ui32Loop++)
               {
               }
        }

}

Right now it is working only in debug mode, but if i change something in the code it is freezing and nothing happening. 

Where should i start to examine? 

So, 2 question lefts for me. 

Why it is only working in debuge mode?

• Should i modify something in the bl_link_css.cmd?

Why is that this code can run in debuge mode but if i change something it stuck

I read the SW-TM4C-BOOTLDR-UG-2.2.0.295.

Any helping hand is welcome.

Im using  CCS Version: 10.2.0.00009, TivaWare_C_Series-2.2.0.295.

I really appreciate that if we can start conversion with these problems and would be a great if you can suggest better ideas.

Stay safe and keep calm.