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LPC84x Watchdog does not always work

Question asked by Hasse Muller on Feb 11, 2019
Latest reply on Feb 11, 2019 by Erich Styger

We are having problems with the watchdog on a LPC845.

We are trying to force a watchdog reset on purpose because there is no other way to reset the LPC845. 

 

The problem:

On some hardware it works, on other equal hardware it simply does not trigger. Out of 50 PCB's we have about 10 failing on watchdog reset.

 

our code:

__disable_irq(); //Disable Interrupts

 

SYS_PeripheralEnableClock(SYS_PERIPHERAL_WWDT);
SYS_HardwareBlockPowerUp(SYS_POWER_HARDWARE_BLOCK_WDTOSC);

 

// The LPC_WWDT_T->TC value after reset (0xFF) is fine:
// that is the minimum value
LPC_WWDT->TC = 0xff; // not really needed

 

LPC_WWDT->MOD = 0x03; // Enable the watchdog and make it generate a
// chip reset at timeout

 

// Start the watchdog
LPC_WWDT->FEED = 0xAA;
LPC_WWDT->FEED = 0x55;


while (1); // on some hardware this triggers watchdog reset, on other hardware it simply stays here forever.

 

 

 

Hope someone knows a line of code that is required for getting the watchdog to work all the time... 

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