TM4C1290NCPDT: GPIOPinWrite not working as expected

Priya Nadathur70

Expert 2795 points

Part Number: TM4C1290NCPDT

I am trying to setup a debug pin for the application. The scope is not triggering a pulse on

the pin write. Is there anything wrong with the code pasted below?

Thanks,

Priya

void Debug_GPIO_Initialise(Bool debugGpioInitialise)
{

//Set Pins as Output

    if (debugGpioInitialise == TRUE)
    {
        ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOL);
        ROM_GPIOPinTypeGPIOOutput(HW_DEBUG_GPIO_PORT_BASE, HW_DEBUG_GPIO_PIN);
        GPIOPadConfigSet(HW_DEBUG_GPIO_PORT_BASE,HW_DEBUG_GPIO_PIN, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD);
        ROM_GPIOPinWrite(HW_DEBUG_GPIO_PORT_BASE, HW_DEBUG_GPIO_PIN, 0);
    }

}

ROM_GPIOPinWrite (HW_DEBUG_GPIO_PORT_BASE, HW_DEBUG_GPIO_PIN, HW_DEBUG_GPIO_PIN);
PRINTHEAD_Delay1us(10);
ROM_GPIOPinWrite (HW_DEBUG_GPIO_PORT_BASE, HW_DEBUG_GPIO_PIN, 0);

over 6 years ago

0 Ralph Jacobi over 6 years ago

TI__Guru*** 135355 points

Hello Priya,

Can you post the defines for HW_DEBUG_GPIO_PORT_BASE and HW_DEBUG_GPIO_PIN?

Also if you debug your code and pause it, do you end up in a FaultISR at any point? If so you may need to use

while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOL))
{
}

before calling ROM_GPIOPinTypeGPIOOutput

0 Priya Nadathur70 over 6 years ago in reply to Ralph Jacobi

Expert 2795 points

//PN
#define HW_DEBUG_GPIO_PORT_BASE GPIO_PORTL_BASE
#define HW_DEBUG_GPIO_PIN GPIO_PIN_3 //PL3
//PN

Adding the while statement didn't change anything.

Appreciate pointers.

Thanks,

PRiya

0 Ralph Jacobi over 6 years ago in reply to Priya Nadathur70

TI__Guru*** 135355 points

Hello Priya,

The only thing I can think at this point is that your PRINTHEAD_Delay1us(10); function is causing an issue.

I took your code and ran it on my LaunchPad but substituted the PRINTHEAD_Delay1us(10); with a SysCtlDelay as I don't have access to the PRINTHEAD_Delay1us function and it toggled the GPIO without any modifications.

Also make sure you properly connected your o-scope to PL3 and that it is set with the right trigger levels.

0 Priya Nadathur70 over 6 years ago in reply to Ralph Jacobi

Expert 2795 points

I put in SysCtlDelay(g_ui32SysClock/200000);

The only time a faint trigger was seen was when the GPIOPadSet was set to WPU.

Is there a combination of pad set and external pull up resistor that might trigger better?

Thanks,

Priya

0 Ralph Jacobi over 6 years ago in reply to Priya Nadathur70

TI__Guru*** 135355 points

Hello Priya,

That is a very small delay, what do you see if you use something like:

SysCtlDelay(g_ui32SysClock/20000);

Though with SysClock running at 120 MHz and using your setup for SysCtlDelay, I am still able to observe the high for 15 uSec with my logic state analyzer while using:

GPIOPadConfigSet(GPIO_PORTL_BASE, GPIO_PIN_3, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD);

0 Priya Nadathur70 over 6 years ago in reply to Ralph Jacobi

Expert 2795 points

Yes, the delay has been changed. To see the pulse, weak pull up with 8mA strength seemed to help. With this, the pulse is a little less than a volt. Are you seeing a good 3.3 V pulse?

Thanks,

Priya

0 Ralph Jacobi over 6 years ago in reply to Priya Nadathur70

TI__Guru*** 135355 points

Hello Priya,

See attached scope shot for SysCtlDelay(g_ui32SysClock/200000);

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TM4C1290NCPDT: GPIOPinWrite not working as expected