WatchDog Timer Driver

Overview

Watchdog driver API definitions.

The watchdog hardware is designed as following :

• There is a shared prescaler provide a periodic tick.
• There is one/multiple counters which increment when the prescaler overflow.
• Each of those counters will have its own "limit" register which will specify when it will generate its own interrupt.
• All counters and the "softPanic" can be cleared together by the software executing a heartbeat.
• Typicaly, the watchdog can be configured to have two counters:
• Counter 0 would provide an interrupt to let's the CPU handle the issue or shutdown the system cleanly.
• Counter 1, configured to trigger after counter 0, would be connected in hardware to reset the whole system in a hard way.

Usage & Initialization.

This is an example show how to instantiate WATCHDOG with watchdog_instance_t.

This implementation depends on PLIC Controller Driver for interrupt configuration.

#include "watchdog/watchdog.h"
#include "irq.h"
 
#define WDG_0 ((watchdog_hwreg_t *)SYSTEM_WATCHDOG_CTRL)
#define WATCHDOG_PRESCALER_CYCLE_PER_MS SYSTEM_CLINT_HZ/1000
#define WATCHDOG_TIMEOUT_MS 3000
 
  // Handle the WDG interrupt
int irq_m_watchDog0_handler(){}
 
watchdog_instance_t wdg_0 = {
    .hwreg          = WDG_0,
    .enable         = {0x1U, 0x1U},
    .prescaler      = WATCHDOG_PRESCALER_CYCLE_PER_MS-1,
    .counterLimit   = {WATCHDOG_TIMEOUT_MS, 2*WATCHDOG_TIMEOUT_MS},
    .heartbeat      = 0x0U,
};
 
plic_instance_t wdg_plic = {
 .target    = BSP_PLIC_CPU_0, 
 .gateway   = SYSTEM_WATCHDOG_INTERRUPTS_0, 
 .priority   = 0x1U, 
 .enable     = 0x1U, 
 .threshold  = 0x0U, 
};
 
void wdg_isr_init(){
    plic_applyConfig(&wdg_plic);
    watchdog_applyConfig(&wdg_0);
    irq_setTrapVector(trap_entry);
    irq_setType(IRQ_EXTERNAL);
    irq_enable();
}

See also

Example Watchdog Timer Demo - Learn how to use the driver for watchdog operations

Topics
	API Functions
	Function definitions for Watchdog driver.
	Data Structures
	Structs used by the driver.
	Data Types
	Enums used by the driver.