OVMS3-idf/components/log
xiehang d71ac521cf esp_wifi: backport some wifi bugs 0323
1,Reduce WiFi bin size
2,Add TX packets size check
3,Fix scan get rssi error
4,Add wifi stop check at WiFi deinit entry
5,coex adjust scheme when bt is connected status
6,Return fail when setting AP's channel is out of range
7,Fix the bug for setting channel when WiFi in NULL mode
2020-03-24 15:10:31 +08:00
..
include esp_wifi: backport some wifi bugs 0323 2020-03-24 15:10:31 +08:00
CMakeLists.txt components: use new component registration api 2019-06-21 19:53:29 +08:00
component.mk remove executable permission from source files 2018-05-29 20:07:45 +08:00
Kconfig Correct Kconfigs according to the coding style 2019-01-29 13:37:01 +01:00
log.c esp_wifi: backport some wifi bugs 0323 2020-03-24 15:10:31 +08:00
README.rst Review log.rst and index.rst files in api-reference/system 2019-04-11 15:33:38 +08:00

Logging library
===============

Overview
--------

The logging library provides two ways for setting log verbosity:

- **At compile time**: in menuconfig, set the verbosity level using the option :envvar:`CONFIG_LOG_DEFAULT_LEVEL`. All logging statements for verbosity levels higher than :envvar:`CONFIG_LOG_DEFAULT_LEVEL` will be removed by the preprocessor.
- **At runtime**: all logs for verbosity levels lower than :envvar:`CONFIG_LOG_DEFAULT_LEVEL` are enabled by default. The function :cpp:func:`esp_log_level_set` can be used to set a logging level on a per module basis. Modules are identified by their tags, which are human-readable ASCII zero-terminated strings.

There are the following verbosity levels:

- Error (lowest)
- Warning
- Info
- Debug
- Verbose (highest)

.. note::

    The function :cpp:func:`esp_log_level_set` cannot set logging levels higher than specified by :envvar:`CONFIG_LOG_DEFAULT_LEVEL`. To increase log level for a specific file at compile time, use the macro `LOG_LOCAL_LEVEL` (see the details below).


How to use this library
-----------------------

In each C file that uses logging functionality, define the TAG variable as shown below:

.. code-block:: c

   static const char* TAG = "MyModule";

Then use one of logging macros to produce output, e.g:

.. code-block:: c

   ESP_LOGW(TAG, "Baud rate error %.1f%%. Requested: %d baud, actual: %d baud", error * 100, baud_req, baud_real);

Several macros are available for different verbosity levels:

* ``ESP_LOGE`` - error (lowest)
* ``ESP_LOGW`` - warning
* ``ESP_LOGI`` - info
* ``ESP_LOGD`` - debug
* ``ESP_LOGV`` - verbose (highest)

Additionally, there are ``ESP_EARLY_LOGx`` versions for each of these macros, e.g., :c:macro:`ESP_EARLY_LOGE`. These versions have to be used explicitly in the early startup code only, before heap allocator and syscalls have been initialized. Normal ``ESP_LOGx`` macros can also be used while compiling the bootloader, but they will fall back to the same implementation as ``ESP_EARLY_LOGx`` macros.

To override default verbosity level at file or component scope, define the ``LOG_LOCAL_LEVEL`` macro.

At file scope, define it before including ``esp_log.h``, e.g.:

.. code-block:: c

   #define LOG_LOCAL_LEVEL ESP_LOG_VERBOSE
   #include "esp_log.h"

At component scope, define it in the component makefile:

.. code-block:: make

   CFLAGS += -D LOG_LOCAL_LEVEL=ESP_LOG_DEBUG

To configure logging output per module at runtime, add calls to the function :cpp:func:`esp_log_level_set` as follows:

.. code-block:: c

   esp_log_level_set("*", ESP_LOG_ERROR);        // set all components to ERROR level
   esp_log_level_set("wifi", ESP_LOG_WARN);      // enable WARN logs from WiFi stack
   esp_log_level_set("dhcpc", ESP_LOG_INFO);     // enable INFO logs from DHCP client

Logging to Host via JTAG
^^^^^^^^^^^^^^^^^^^^^^^^

By default, the logging library uses the vprintf-like function to write formatted output to the dedicated UART. By calling a simple API, all log output may be routed to JTAG instead, making logging several times faster. For details, please refer to Section :ref:`app_trace-logging-to-host`.