diff --git a/components/esp32/include/esp_int_wdt.h b/components/esp32/include/esp_int_wdt.h index 4387400396..b32d0219fb 100644 --- a/components/esp32/include/esp_int_wdt.h +++ b/components/esp32/include/esp_int_wdt.h @@ -41,9 +41,6 @@ This uses the TIMERG1 WDT. * @brief Initialize the interrupt watchdog. This is called in the init code if * the interrupt watchdog is enabled in menuconfig. * - * @param null - * - * @return null */ void esp_int_wdt_init(); diff --git a/components/esp32/include/esp_task_wdt.h b/components/esp32/include/esp_task_wdt.h index bbc4995674..eb77377009 100644 --- a/components/esp32/include/esp_task_wdt.h +++ b/components/esp32/include/esp_task_wdt.h @@ -42,9 +42,6 @@ This uses the TIMERG0 WDT. * @brief Initialize the task watchdog. This is called in the init code, if the * task watchdog is enabled in menuconfig. * - * @param null - * - * @return null */ void esp_task_wdt_init(); @@ -52,9 +49,6 @@ void esp_task_wdt_init(); * @brief Feed the watchdog. After the first feeding session, the watchdog will expect the calling * task to keep feeding the watchdog until task_wdt_delete() is called. * - * @param null - * - * @return null */ void esp_task_wdt_feed(); @@ -63,9 +57,6 @@ void esp_task_wdt_feed(); /** * @brief Delete the watchdog for the current task. * - * @param null - * - * @return null */ void esp_task_wdt_delete(); diff --git a/docs/Doxyfile b/docs/Doxyfile index 6ff4c45860..d5970ee5e9 100644 --- a/docs/Doxyfile +++ b/docs/Doxyfile @@ -1,6 +1,8 @@ PROJECT_NAME = "ESP32 Programming Guide" -INPUT = ../components/esp32/include/esp_wifi.h ../components/driver/include/driver ../components/bt/include ../components/nvs_flash/include ../components/log/include ../components/vfs/include +INPUT = ../components/esp32/include/esp_wifi.h ../components/driver/include/driver ../components/bt/include \ + ../components/nvs_flash/include ../components/log/include ../components/vfs/include \ + ../components/esp32/include/esp_int_wdt.h ../components/esp32/include/esp_task_wdt.h WARN_NO_PARAMDOC = YES diff --git a/docs/api/wdts.rst b/docs/api/wdts.rst new file mode 100644 index 0000000000..1b476f2f79 --- /dev/null +++ b/docs/api/wdts.rst @@ -0,0 +1,72 @@ +Watchdogs +========= + +Overview +-------- + +Esp-idf has support for two types of watchdogs: a task watchdog as well as an interrupt watchdog. Both can be +enabled using ``make menuconfig`` and selecting the appropriate options. + +Interrupt watchdog +^^^^^^^^^^^^^^^^^^ + +The interrupt watchdog makes sure the FreeRTOS task switching interrupt isn't blocked for a long time. This +is bad because no other tasks, including potentially important ones like the WiFi task and the idle task, +can't get any CPU runtime. A blocked task switching interrupt can happen because a program runs into an +infinite loop with interrupts disabled or hangs in an interrupt. + +The default action of the interrupt watchdog is to invoke the panic handler. causing a register dump and an opportunity +for the programmer to find out, using either OpenOCD or gdbstub, what bit of code is stuck with interrupts +disabled. Depending on the configuration of the panic handler, it can also blindly reset the CPU, which may be +preferred in a production environment. + +The interrupt watchdog is built around the hardware watchdog in timer group 1. If this watchdog for some reason +cannot execute the NMI handler that invokes the panic handler (e.g. because IRAM is overwritten by garbage), +it will hard-reset the SOC. + +Task watchdog +^^^^^^^^^^^^^ + +Any tasks can elect to be watched by the task watchdog. If such a task does not feed the watchdog within the time +specified by the task watchdog timeout (which is configurable using ``make menuconfig``), the watchdog will +print out a warning with information about which processes are running on the ESP32 CPUs and which processes +failed to feed the watchdog. + +By default, the task watchdog watches the idle tasks. The usual cause of idle tasks not feeding the watchdog +is a higher-priority process looping without yielding to the lower-priority processes, and can be an indicator +of badly-written code that spinloops on a peripheral or a task that is stuck in an infinite loop. + +Other task can elect to be watched by the task watchdog by calling ``esp_task_wdt_feed()``. Calling this routine +for the first time will register the task to the task watchdog; calling it subsequent times will feed +the watchdog. If a task does not want to be watched anymore (e.g. because it is finished and will call +``vTaskDelete()`` on itself), it needs to call ``esp_task_wdt_delete()``. + +The task watchdog is built around the hardware watchdog in timer group 0. If this watchdog for some reason +cannot execute the interrupt handler that prints the task data (e.g. because IRAM is overwritten by garbage +or interrupts are disabled entirely) it will hard-reset the SOC. + +JTAG and watchdogs +^^^^^^^^^^^^^^^^^^ + +While debugging using OpenOCD, if the CPUs are halted the watchdogs will keep running, eventually resetting the +CPU. This makes it very hard to debug code; that is why the OpenOCD config will disable both watchdogs on startup. +This does mean that you will not get any warnings or panics from either the task or interrupt watchdog when the ESP32 +is connected to OpenOCD via JTAG. + +API Reference +------------- + +Header Files +^^^^^^^^^^^^ + + * `esp32/include/esp_int_wdt.h `_ + * `esp32/include/esp_task_wdt.h `_ + + +Functions +--------- + +.. doxygenfunction:: esp_int_wdt_init +.. doxygenfunction:: esp_task_wdt_init +.. doxygenfunction:: esp_task_wdt_feed +.. doxygenfunction:: esp_task_wdt_delete diff --git a/docs/index.rst b/docs/index.rst index 1ca6e28eec..c19fc52c9a 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -42,9 +42,9 @@ Contents: 1.2. Application startup flow - TBA 1.3. Flash encryption and secure boot: how they work and APIs - TBA 1.4. Lower Power Coprocessor - TBA - 1.5. Watchdogs + 1.5. Watchdogs 1.6. ... - 2. Memeory - TBA + 2. Memory - TBA 2.1. Memory layout of the application (IRAM/IROM, limitations of each) - TBA 2.2. Flash layout and partitions - TBA 2.3. Flash access APIs - TBA @@ -92,6 +92,7 @@ Contents: Wi-Fi Bluetooth + Watchdogs api/gpio api/uart