TM4C129ENCPDT: Clock Watchdog1 from RTCOSC via ALTCLK?

Hi Brian,

  I have some update. What is missing in your code is that you did not output the hibernate clock to the system although you enable the hibernate clock. I happen to stumble on this too. This is why I don't see the RTC going to the watchdog module. Once I enable it, it is all good.  What you need is the HWREG(HIB_CC) = 0x1. 

//*****************************************************************************
//
// watchdog_rtcosc.c - Watchdog timer example.
//
// Copyright (c) 2013-2017 Texas Instruments Incorporated.  All rights reserved.
// Software License Agreement
// 
// Texas Instruments (TI) is supplying this software for use solely and
// exclusively on TI's microcontroller products. The software is owned by
// TI and/or its suppliers, and is protected under applicable copyright
// laws. You may not combine this software with "viral" open-source
// software in order to form a larger program.
// 
// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT
// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY
// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
// DAMAGES, FOR ANY REASON WHATSOEVER.
// 
// This is part of revision 2.1.4.178 of the EK-TM4C1294XL Firmware Package.
//
//*****************************************************************************

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include <time.h>
#include "inc/hw_hibernate.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/sysctl.h"
#include "driverlib/hibernate.h"
#include "driverlib/watchdog.h"
#include "driverlib/rom.h"
#include "driverlib/rom_map.h"
#include "drivers/buttons.h"
#include "driverlib/hibernate.h"

//*****************************************************************************
//
//! \addtogroup example_list
//! <h1>Watchdog (watchdog)</h1>
//!
//! This example application demonstrates the use of the watchdog as a simple
//! heartbeat for the system.  If the watchdog is not periodically fed, it will
//! reset the system.  Each time the watchdog is fed, the LED is inverted so
//! that it is easy to see that it is being fed, which occurs once every
//! second.  To stop the watchdog being fed and, hence, cause a system reset,
//! press the SW1 button.
//
//*****************************************************************************

//****************************************************************************
//
// System clock rate in Hz.
//
//****************************************************************************
uint32_t g_ui32SysClock;

//*****************************************************************************
//
// Flag to tell the watchdog interrupt handler whether or not to clear the
// interrupt (feed the watchdog).
//
//*****************************************************************************
volatile bool g_bFeedWatchdog = true;

//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, uint32_t ui32Line)
{
}
#endif

//*****************************************************************************
//
// The interrupt handler for the watchdog.  This feeds the dog (so that the
// processor does not get reset) and winks the LED connected to GPIO B3.
//
//*****************************************************************************
void
WatchdogIntHandler(void)
{
    //
    // If we have been told to stop feeding the watchdog, return immediately
    // without clearing the interrupt.  This will cause the system to reset
    // next time the watchdog interrupt fires.
    //
    if(!g_bFeedWatchdog)
    {
        return;
    }

    //
    // Clear the watchdog interrupt.
    //
    ROM_WatchdogIntClear(WATCHDOG1_BASE);

    //
    // Invert the GPIO PN0 value.
    //
    ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0,
                     (ROM_GPIOPinRead(GPIO_PORTN_BASE, GPIO_PIN_0) ^
                                     GPIO_PIN_0));
}

//*****************************************************************************
//
// This function is called when the SW1 button is pressed.
//
//*****************************************************************************
static int32_t
SW1ButtonPressed(void)
{
    //
    // Set the flag that tells the interrupt handler not to clear the
    // watchdog interrupt.
    //
    g_bFeedWatchdog = false;

    return(0);
}

//*****************************************************************************
//
// This example demonstrates the use of the watchdog timer.
//
//*****************************************************************************
int
main(void)
{
    //
    // Set the clocking to run directly from the crystal at 120MHz.
    //
    g_ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
                                             SYSCTL_OSC_MAIN |
                                             SYSCTL_USE_PLL |
                                             SYSCTL_CFG_VCO_480), 120000000);
    //
    // Setup PD1 as input pin with internal pullup enabled. Only when PD1 is
    // connected to ground will allow the code to continue execution.

    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
    while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOD)));
    GPIOPinTypeGPIOInput(GPIO_PORTD_BASE, GPIO_PIN_1);
    GPIOPadConfigSet(GPIO_PORTD_BASE, GPIO_PIN_1, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD_WPU);

    // wait here while PD1 is high. Need to connect PD1 to GND to continue the rest of
    // code execution. This is to prevent the device from being locked out unable to connect.
    while (GPIOPinRead(GPIO_PORTD_BASE, GPIO_PIN_1));

    //
    // Initialize the buttons driver.
    //
    ButtonsInit();

    //
    // Enable the peripherals used by this example.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_WDOG1);
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);

    //
    // Enable processor interrupts.
    //
    ROM_IntMasterEnable();

    //
    // Set GPIO PN0 as an output.  This drives an LED on the board that will
    // toggle when a watchdog interrupt is processed.
    //
    ROM_GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE, GPIO_PIN_0);
    ROM_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, 0);

    //
    // Enable the watchdog interrupt.
    //
    ROM_IntEnable(INT_WATCHDOG);

    //
    // Set the period of the watchdog timer to 1 second. The ALTCLK
    // is the RTCOSC which is 32.768kHz. Load 32668 to the watchdog
    // reload register for one second timeout
    //
    WatchdogReloadSet(WATCHDOG1_BASE, 32768);
    //
    // Enable reset generation from the watchdog timer.
    //
    ROM_WatchdogResetEnable(WATCHDOG1_BASE);

    // Enable stall during debug mode
    WatchdogStallEnable(WATCHDOG1_BASE);

    //
    // Enable the hibernate module.
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_HIBERNATE);

    //
    // Enable the Hibernation module for operation.
    //
    HibernateEnableExpClk(0);

    //
    // Wait for 32.768kHz clock to stabilize.
    //
    while(!(HWREG(HIB_RIS) & HIB_RIS_WC));

    //
    // Configure the drive strength for the crystal.
    //
    HibernateClockConfig(HIBERNATE_OSC_LOWDRIVE);

    //
    // Enable Hibernate RTC clock (32.768kHz) to output to the
    // the system.
    //
    HWREG(HIB_CC) = 0x1;

    //
    // Enable the Hibernate module RTC mode.
    //
    HibernateRTCEnable();

    //
    // Load initial RTC value.
    //
    HibernateRTCSet(0);

    //
    // Configure RTCOSC as the alternate clock source
    //
    SysCtlAltClkConfig(SYSCTL_ALTCLK_RTCOSC);

    //
    // Enable the watchdog timer.
    //
    ROM_WatchdogEnable(WATCHDOG1_BASE);

    //
    // Loop forever while the LED winks as watchdog interrupts are handled.
    //
    while(1)
    {
        //
        // Poll for the select button pressed
        //
        uint8_t ui8Buttons = ButtonsPoll(0, 0);
        if(ui8Buttons & USR_SW1)
        {
            SW1ButtonPressed();
            while(1)
            {
            }
        }
    }
}