Watchdog Reset

[lpcware]

Content originally posted in LPCWare by pcalton on Thu Nov 07 11:18:08 MST 2013
I have been trying to add the watchdog to my application to reset the processor if the software hangs using the following setup routine

#define MHz(x) (x * 1000000)

#define WDT_MAX_TIME 5000 // 5 seconds (Max 5592)
#define WDT_MIN_TIME 1 // 1 millisecond

void Board_WWDT_Init(void)
{
// Windowed watchdog runs from internal RC osc at 12MHz with fixed div by 4 prescale.
// 24 bit counter decremented from timeout value to zero (reset core at zero)
// feed resets counter to timeout value
// feed with counter above window value results in a core reset
const uint32_t wdt_count_per_ms = (MHz(12) / 4) / 1000;
const uint32_t wdt_timeout = WDT_MAX_TIME * wdt_count_per_ms;
const uint32_t wdt_window = (WDT_MAX_TIME - WDT_MIN_TIME) * wdt_count_per_ms;

Chip_WWDT_Init(LPC_WWDT);
Chip_WWDT_SetTimeOut(LPC_WWDT, wdt_timeout);
Chip_WWDT_SetOption(LPC_WWDT, WWDT_WDMOD_WDRESET);
Chip_WWDT_ClearStatusFlag(LPC_WWDT, WWDT_WDMOD_WDTOF | WWDT_WDMOD_WDINT);
Chip_WWDT_SetWindow(LPC_WWDT, wdt_window);
Chip_WWDT_Start(LPC_WWDT);
}

To test my setup I purposefully allowed the watchdog to expire, expecting the software to reset and restart. The software certainly stopped after 5 seconds, but didnt restart.

To check whether I had missed anything I loaded up the keil lpcopen peripheral example for the watchdog on a clean un-modded MCB4357 board

That application allows interaction via usart3 with the option to disable the feed and reset the device. When I selected this option the flashing led that indicated program life stopped and then to my surprise the LCD lit up showing MCB4300 Demo Example.

If I press the external reset button, the watchdog example starts again and runs until I select the option to disable feeding at which point the MCB4300 Demo Example appears. I can only assume that following the watchdog reset the processor is booting out of external memory even though there is a valid application in the internal flash.

Could someone please explain what is happening and how to rectify it so that the internal flash application starts following a watchdog reset?

[lpcware]

Content originally posted in LPCWare by pcalton on Wed Nov 20 11:14:39 MST 2013
For anyone facing a similar problem, I managed to get the following response from NXP support

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Quote:
That looks like an issue with the MCB4350 board.
Remove C97 (in parallel to the ISP pushbutton).

When populated, C97 charges to a level which depends on A9 address line activity.
After a watchdog reset, the device almost immediately checks P2_7 (=A9). If low, the device boots depending on the four boot switches on the board. These may well be in the position to boot the demo code from external memory.

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Removing C97 fixed my problem

[lpcware]

Content originally posted in LPCWare by pcalton on Wed Nov 13 11:20:10 MST 2013
Is anyone able to provide any feedback on this please?