I am trying to use the watchdog interrupt on an NRF52832 but am unable to get it to fire; the watchdog fires, but as far as I can tell not the preceding interrupt. Here is some sample code to show the problem:
#include "mbed.h"
#include <SerialWireOutput.h>
// An unsigned int in an uninitialised RAM area
#if defined(__CC_ARM) || (defined(__ARMCC_VERSION) && (__ARMCC_VERSION >= 6010050))
__attribute__ ((section(".bss.uninitialised"),zero_init))
unsigned int gRetained;
#elif defined(__GNUC__)
__attribute__ ((section(".uninitialised")))
unsigned int gRetained;
#elif defined(__ICCARM__)
unsigned int gRetained @ ".uninitialised";
#endif
// Hook into the weak function to allow Serial Wire Output (because that's how my board speaks to the world)
namespace mbed {
FileHandle *mbed_target_override_console(int)
{
static SerialWireOutput swo;
return &swo;
}
}
// Watchdog interrupt handler
void WDT_IRQHandler(void)
{
gRetained++;
NRF_WDT->EVENTS_TIMEOUT = 0;
}
// Entry point
int main()
{
printf("\nStarting up and setting the watchdog timer to 5 seconds.\n");
// Setting watchdog to 10 seconds
// Set timeout value timeout [s] = ( CRV + 1 ) / 32768
NRF_WDT->CRV = (5 * 32768) - 1;
NVIC_SetPriority(WDT_IRQn, 7);
NVIC_ClearPendingIRQ(WDT_IRQn);
NVIC_EnableIRQ(WDT_IRQn);
NRF_WDT->INTENSET = 1;
NRF_WDT->TASKS_START = 1;
printf("Retained RAM variable is %d.\n", gRetained);
if (gRetained > 2) {
printf("Setting retained RAM variable to 0 and resetting...\n");
gRetained = 0;
wait_ms(1000);
NVIC_SystemReset();
}
gRetained++;
printf("Retained RAM variable incremented to %d.\n", gRetained);
if (gRetained < 2) {
printf("Resetting...\n");
wait_ms(1000);
NVIC_SystemReset();
} else {
printf("Now waiting for 10 seconds so that the watchdog goes off, which should increment the retained RAM variable to %d.\n",
gRetained + 1);
wait_ms(10000);
}
printf("Should never get here.\n");
while(1) {}
}
This code should show that the retained RAM variable is retained across a reset (so it really is being retained) and when the watchdog reset occurs, the retained RAM variable should be incremented by the watchdog interrupt. However the output (compiled under ARMCC) shows that it is not:
Starting up and setting the watchdog timer to 5 seconds.
Retained RAM variable is 0.
Retained RAM variable incremented to 1.
Resetting...
Starting up and setting the watchdog timer to 5 seconds.
Retained RAM variable is 1.
Retained RAM variable incremented to 2.
Now waiting for 10 seconds so that the watchdog goes off, which should increment the retained RAM variable to 3.
Starting up and setting the watchdog timer to 5 seconds.
Retained RAM variable is 2.
...
Can anyone spot what I'm doing wrong?
Rob
