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Setting GPIO H3 as output causes memory overwright

yanki schon
Prodigy 40 points

Hello all,

I'm using LM4F232H5QD on a custom board.

compiler: IAR, Embedded Workbench 6.4

The system runs with clock of 80Mhz

During HW init procedure, GPIO H3 is configured as output as following:

ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOH);
ROM_GPIOPinTypeGPIOOutput(GPIO_PORTH_BASE, GPIO_PIN_3);
ROM_GPIODirModeSet(SYSCTL_PERIPH_GPIOH, GPIO_PIN_3, GPIO_DIR_MODE_OUT);

When ROM_GPIODirModeSet is executed, memory ovewrite occurs on address: 0x200004A0.

This address holds data of a global variable.

I get this behaviour when using both debuggers I-Jet and J-Link, and also when running free without debugger and loading the FW using the boot loader through UART0 using LM Flash Programmer.

The variable, which is being overwritten is a cell in array of pointers.

The array is defined as follow:

static char *ptSystemBIT[]=
{
"\r\nSystem Diagnostics\r\n",
"------------------\r\n",
"1. General BIT\r\n",
"2. R&D Internal\r\n",
"3. Keyboard\r\n",
"4. Mouse\r\n",
"5. Face\r\n",
"6. Back to main menu\r\n\r\n"
};

Map file allocation is as follow:

ptSystemBIT             0x20000490   0x20  Data  Lc  UserInterface.o [1]

I don't understand how GPIO setting can cause this problem. I tried other GPIO and it was ok (or it could be I get memory overwrite in a place I didn't find).

I'll appreciate any help.

Thank you all in advance,

Yanki

  • 0
    Guru 26105 points

    Hi,

    I think you are passing a wrong parameter (the first one) when calling GPIODirModeSet() - this should be GPIO_PORTH_BASE instead SYSCTL_xxxx - the library code shows for this parameter : ui32Port.

    Petrei

  • 0 in reply to Petrei
    Prodigy 40 points

    Hi Petrei,

    Thank you for your fast response.

    Accordinh to ROM user guide document, the parameter should be SYSCTL_PERIPH_..., but I also noticed the note there:

    It takes five clock cycles after the write to enable a peripheral before the the peripheral is
    actually enabled. During this time, attempts to access the peripheral will result in a bus fault.
    Care should be taken to ensure that the peripheral is not accessed during this brief time period.

    I entered a delay using ROM_SysCtlDelay and it seems to be o.k now.

    I hope this solves my problem.

    Yanki

  • 0 in reply to yanki schon
    Prodigy 40 points

    Hello again,

    Petrei, I apologize. You are right. I mixed up with ROM_SysCtrlPeripheralEnable.

    I wish you all the best.

    Yanki