Analyze the Current Configuration
- Start by reviewing your MCU's hardware datasheet or reference manual to understand the watchdog timer (WDT) functionality and configuration registers.
- Identify the part of your firmware where the watchdog timer is configured. Look for initialization routines or configuration functions.
- Evaluate the time limits set within your watchdog timer register configurations. Compare them to the requirements specified in your project.
Correct the Configuration Code
- Locate the code where the watchdog timer is initialized. This might be in a specific function, such as `init_watchdog()`, or within your main routine setup.
- Ensure the time-out period is set accurately to suit your application's needs. Adjust the WDT configuration registers accordingly. For instance, if you need to adjust the time-out period in your code, modify lines similar to the following example:
```c
// Example for an arbitrary microcontroller
// Set the watchdog timeout period
WDTCSR = (1 << WDP2) | (1 << WDP1); // Example: sets a specific timeout value
// Enable WDT
WDTCSR |= (1 << WDE);
```
Ensure the bit positions and register names align with your microcontroller's documentation.
Incorporate a mechanism to refresh or "pet" the watchdog timer periodically within your code. This can typically be done within your main loop or critical operational routines:
```c
// Example: Clear WDT to prevent reset
wdt_reset();
```
Modify according to your toolchain or architecture specifics.
Validate the Changes
- Compile and flash the firmware onto your hardware, ensuring your toolchain is set up to utilize the recent code changes you've made.
- Test the watchdog functionality by simulating scenarios where the main loop would encounter delays or hang up. Confirm that the watchdog triggers as expected if the system becomes unresponsive.
- Observe the newly set watchdog timeouts in action. You may want to use a debugger or console output to ensure the WDT reset is only called appropriately and within the required intervals.
Optimize WDT Usage
- Fine-tune the watchdog timer configuration. After initial validation, adjust the timeout duration to the minimal acceptable period that provides adequate error detection without causing false resets.
- Implement exception handling or state logging to help identify the cause of a watchdog reset when it occurs. Logging resets can help diagnose underlying issues with tasks that overrun their time allocation.
- Consider using a multi-stage watchdog if available. Some architectures allow for warnings before a hard reset, providing additional time for corrective actions when the system is under duress.
