RISCV_Watchdog User Guide
REVISION HISTORY¶
| Revision No. | Description |
Date |
|---|---|---|
| 1.0 | 04/21/2023 |
1. OVERVIEW¶
The hardware watchdog provides a timeout reset system function, which consists of a timer and a reset function. Users can set a timeout period and perform a "feed dog" operation within the timeout period to reset its internal count. If its internal calculation reaches the set timeout period, the watchdog will reset the system and restart it.
2. KEYWORD DESCRIPTION¶
-
watchdog
A watchdog is a timer circuit that typically has an input called "kick the dog/service the dog" and an output to the RST terminal of the MCU. When the MCU is working normally, it outputs a signal to the dog feeding terminal at regular intervals to reset the WDT. If the WDT timer exceeds the specified time (usually when the program runs out), it will give a reset signal to the MCU to reset it. Prevent MCU from crashing The role of a watchdog is to prevent the program from looping or running away.
-
watchdog timeout
The timeout duration of the watchdog. If the watchdog is not fed after this duration, the WDT timer will exceed, and a reset signal will be sent to the MCU to reset it.
-
watchdog pretimeout
The pre timeout duration of the watchdog. Pretimeout is the length of time from the trigger time to the system restart time point. For example, if you set the timeout to 60, Pretimeout is 10, so the mechanism will be triggered at 50 seconds (10 seconds before restart).
3. FUNCTION DESCRIPTION¶
The Linux kernel supports softdogs based on hrtimer and hardware watchdogs based on hardware, creating/dev/watchdog* device files to interact with user space programs. The watchdog program in user space will feed dogs periodically through the/dev/watchdog* device.
4. HARDWARE CONNECTION INTRODUCTION¶
NA
5. Usage Introduction In RTOS¶
5.1. DRIVER PATH¶
sc/driver/sysdriver/watchdog/drv/mdrv_wdt_api.h
sc/driver/sysdriver/watchdog/drv/mdrv_wdt.c
sc/driver/sysdriver/watchdog/drv/mdrv_wdt_reg.h
sc/driver/sysdriver/watchdog/drv/mdrv_wdt_test.c
5.2. CONFIG Configuration¶
The config file is located at mak/options _pcupid_riscv _isw. mak, with CONFIG-WatchDOG_SUPPORT enabled`
# Feature_Name = [DRV] WATCHDOG driver support # Description = WATCHDOG driver support # Option_Selection = TRUE, FALSE CONFIG_WATCHDOG_SUPPORT = TRUE
5.3. SYSDESC Configuration¶
No configuration is required.
5.4. Padmux Configuration¶
No configuration is required.
5.5. Sample code¶
int watchdog_test(void)
{
int wdt_timeout = 10; /* 10s */
int i = 0;
if(sstar_wdt_probe()!=0)
{
CamOsPrintf("sstar_wdt_probe failed to execute\n");
return -1;
}
if (sstar_wdt_set_timeout(wdt_timeout)!=0) /*Set watchdog timeout*/
{
CamOsPrintf("sstar_wdt_set_timeout failed to execute\n", argc);
return -1;
}
if(sstar_wdt_start()!=0) /*Start watchdog*/
{
CamOsPrintf("sstar_wdt_start failed to execute\n");
return -1;
}
for(i = 0; i < 10; i++){
CamOsMsSleep(wdt_timeout*1000/2); /*Feed the watchdog every 5 seconds, 10 times */
if (sstar_wdt_ping()!=0)
{
return -1;
}
}
/*After 50 seconds, the system will no longer feed the dog. At the 60th second, the watchdog will trigger the system to be restarted*/
return 0;
}
5.6. UT case¶
Test case:
(1) Open the Watchdog macro CONFIG_WATCHDOG_SUPPORT and VER_WATCHDOG
(2) Test demo path: sc/driver/sysdriver/watchdog/drv/mdrv_wdt_test.c
(3) Perform testing
SS-RTOS # wdttest
argv must like start/reset xs,num must be 2, now is: 0
[start/reset] [time (s)]
- Do some tests about wdt'
Example:
# wdttest start 10 /* After starting watchdog, the system will continuously feed the watchdog, so the system will not restart after 10 seconds*/
# wdttest reset 10 /* After starting watchdog, the system will not feed the dog, so the system will restart after 10 seconds*/
6. API reference¶
This functional module provides the following interfaces:
| API Name | Function |
|---|---|
| sstar_wdt_probe | Initialize the watchdog |
| sstar_wdt_remove | Release watchdog |
| sstar_wdt_start | Start watchdog |
| sstar_wdt_stop | Stop watchdog |
| sstar_wdt_set_timeout | Set watchdog timeout |
| sstar_wdt_ping | Feed watchdog |
6.1. sstar_wdt_probe¶
-
Function
Initialize the watchdog
-
Grammar
int sstar_wdt_probe(void);
-
Parameters
Parameter Name Description NA NA -
Return value
Return value Description 0 Successful other Failed
6.2. sstar_wdt_remove¶
-
Function
Release watchdog, if watchdog is running, stop watchdog first
-
Grammar
int sstar_wdt_remove(void);
-
Parameters
Parameter Name Description NA NA -
Return value
Return value Description 0 Successful other Failed
6.3. sstar_wdt_start¶
-
Function
Start WDT according to the set or default timeout
-
Grammar
int sstar_wdt_start(void);
-
Parameters
Parameter Name Description NA NA -
Return value
Return value Description 0 Successful other Failed
6.4. sstar_wdt_stop¶
-
Function
Stop watchdog
-
Grammar
int sstar_wdt_stop(void);
-
Parameters
Parameter Name Description void NA -
Return value
Return value Description 0 Successful other Failed
6.5. sstar_wdt_set_timeout¶
-
Function
Set the length of the WDT timeout. If sstar_wdt_ping is not used periodically to "feed the dog" within this length of time, the system will reset, commonly known as "dog bite"
-
Grammar
int sstar_wdt_set_timeout(unsigned int timeout);
-
Parameters
Parameter Name Description timeout watchdog timeout -
Return value
Return value Description 0 Successful other Failed
6.6. sstar_wdt_ping¶
-
Function
Reset the WDT counter, commonly known as "feeding the dog"
-
Grammar
int sstar_wdt_ping(void);
-
Parameters
Parameter Name Description void NA -
Return value
Return value Description 0 Successful other Failed
7. FAQ¶
NA