[incubator-nuttx-apps] 02/02: examples/readme.txt: Added information about watcher example.

[ac...@apache.org]

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commit cb1a424bc155e92baa86cb25ad27867d12723481
Author: Sara Souza <sa...@espressif.com>
AuthorDate: Thu Dec 10 16:35:46 2020 -0300

    examples/readme.txt: Added information about watcher example.
---
 examples/README.md | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/examples/README.md b/examples/README.md
index 4480644..73c1915 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -1937,6 +1937,63 @@ Specific configuration options for this example include:
 - `CONFIG_EXAMPLES_WATCHDOG_TIMEOUT` – The watchdog timeout value in
   milliseconds before the watchdog timer expires. Default: `2000` milliseconds.
 
+## `watcher` Watcher & Watched
+
+The watcher and watched examples are designed to work together. The watched
+example will only appear after watcher is selected.
+The watcher is a task that will monitor other tasks that subscribe to be watched.
+If a watched task doesn't signal the watcher during the watchdog time period,
+the watchdog timer will expire and the watcher will print the tasks that did
+not signal and the ones that signaled. The tasks that did not signal will be printed
+as the tasks that starved the dog and the tasks that signaled will be printed as 
+the tasks that fed the dog.
+The watcher task will only feed the watchdog timer when all subscribed tasks have
+asked to feed dog.
+
+To start the watcher, just run:
+
+`watcher`
+
+The watched example is not required to use the watcher. The watched example is simply
+a task that creates 4 tasks that will subscribe to be watched. The first and fourth 
+will not feed the dog to expose the functionality. This example will show the user
+how to subscribe, to feed the dog and to unsubscribe. 
+
+To start the watched, just run:
+
+`watched` 
+
+P.S: This example will only be supported by the chips that support interrupt on
+timeout, i.e., which have the \"capture\" command implemented. 
+
+This test depends on these specific configurations settings (your
+specific watchdog hardware settings might require additional settings).
+
+- `CONFIG_EXAMPLES_WATCHER` – Includes this example.
+- `CONFIG_WATCHDOG` – Enables watchdog timer support.
+- `CONFIG_NSH_BUILTIN_APPS` – Build this example an NSH built-in
+  function.
+- `CONFIG_DRIVER_NOTE` and `CONFIG_SCHED_INSTRUMENTATION` – Allows the watcher
+  to get the tasks' names.   
+- `CONFIG_FS_FAT` – Allows the creation of a FAT filesystem on the ramdisk
+  to create a file with all the necessary info for the watched tasks. 
+
+Specific configuration options for the `watcher` example include:
+
+- `CONFIG_EXAMPLES_WATCHER_PRIORITY` – Watcher Task Priority.
+- `CONFIG_EXAMPLES_WATCHER_STACKSIZE` – Watcher Task Stack Size.
+- `CONFIG_EXAMPLES_WATCHER_DEVPATH` – The path to the Watchdog device used by
+  the Watcher. Default: `/dev/watchdog0`.
+- `CONFIG_EXAMPLES_WATCHER_TIMEOUT` – The watchdog timeout value in
+  milliseconds.
+- `CONFIG_EXAMPLES_WATCHER_SIGNAL` – This is the Signal Number used for 
+  communication between the watcher task and the watched tasks.
+
+Specific configuration options for the `watched` example include:
+
+- `CONFIG_EXAMPLES_WATCHED_PRIORITY` – Watched Task Priority.
+- `CONFIG_EXAMPLES_WATCHED_STACKSIZE` – Watched Task Stack Size.
+
 ## `webserver` Simple Webserver
 
 This is a port of uIP tiny webserver example application. Settings specific to