Problem using watchdog to wake up from standby

Jesper Vestergaard

Prodigy 80 points

Hi all,

I want to use the watchdog to periodic wake up from standby, check the adc and then go back to sleep.

The watchdog is set to WAKEINT and works when system is not in standby.

I can wake from standby by pressing a button attached to GPIO14.

I have tried executing the code with and without the debugger attached and there is no difference.

What am i missing?

My standby procedure looks like this:

void LPM_gotoSleep(void)

{

// The wakeup signal should be (2+QUALSTDBY) OSCCLKs wide.
SysCtrlRegs.LPMCR0.bit.QUALSTDBY = 0;

// enable watchdog in standby
SysCtrlRegs.LPMCR0.bit.WDINTE = 1;

EALLOW;

GpioIntRegs.GPIOLPMSEL.all = 0;

// Wake up on control panel press
GpioIntRegs.GPIOLPMSEL.bit.GPIO14 = 1;

if (SysCtrlRegs.PLLSTS.bit.MCLKSTS != 1) // Only enter Standby mode when PLL is not in limp mode.
{
// Write the LPM code value
SysCtrlRegs.LPMCR0.bit.LPM = 0x0001; // LPM mode = Standby
}
EDIS;

// use watchdog to periodic wake from sleep

SysCtrlRegs.WDCR = 0x002F;
WDT_reset();

EALLOW;

SysCtrlRegs.CLKCTL.bit.WDCLKSRCSEL = 1; // Switch Watchdog Clk Src to external

EINT; // Global Enable all Interrupts

// Force device into STANDBY

asm(" IDLE");

}

over 13 years ago

0 Tim Love over 13 years ago

TI__Expert 5340 points

Hello Jesper,

Is the watchdog disabled by default? The reason I ask is because of this particular block of code:

Jesper Vestergaard said:

// use watchdog to periodic wake from sleep

SysCtrlRegs.WDCR = 0x002F;
WDT_reset();

You are attempting to enable the watchdog. However, the WDCR is EALLOW protected and directly before this block of code you have the EDIS command which disables this register from being written to. You can check if this is the issue by wrapping this code in EALLOW and EDIS or just removing the EDIS before the write to the WDCR. Can you test this and let me know if this resolves the issue?

Regards,

Tim Love

0 Tim Love over 13 years ago in reply to Tim Love

TI__Expert 5340 points

I forgot another line of code as well:

// enable watchdog in standby
SysCtrlRegs.LPMCR0.bit.WDINTE = 1;

This register is EALLOW protected but it doesn't appear from this block of code that you have initiated the EALLOW.

Regards,

Tim Love

0 Jesper Vestergaard over 13 years ago in reply to Tim Love

Prodigy 80 points

Thanks Tim,

That was the problem. Now the watchdog wakes up the system just fine.

Regards

Jesper

0 Tim Love over 13 years ago in reply to Jesper Vestergaard

TI__Expert 5340 points

Glad to hear this is working now.

Regards,

Tim

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Problem using watchdog to wake up from standby