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62 lines
1.9 KiB
Markdown
62 lines
1.9 KiB
Markdown
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```eval_rst
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.. include:: /header.rst
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:github_url: |github_link_base|/porting/log.md
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```
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# Logging
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LVGL has built-in *log* module to inform the user about what is happening in the library.
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## Log level
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To enable logging, set `LV_USE_LOG 1` in *lv_conf.h* and set `LV_LOG_LEVEL` to one of the following values:
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- **LV_LOG_LEVEL_TRACE** A lot of logs to give detailed information
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- **LV_LOG_LEVEL_INFO** Log important events
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- **LV_LOG_LEVEL_WARN** Log if something unwanted happened but didn't cause a problem
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- **LV_LOG_LEVEL_ERROR** Only critical issue, when the system may fail
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- **LV_LOG_LEVEL_NONE** Do not log anything
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The events which have a higher level than the set log level will be logged too. E.g. if you `LV_LOG_LEVEL_WARN`, *errors* will be also logged.
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## Logging with printf
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If your system supports `printf`, you just need to enable `LV_LOG_PRINTF` in *lv_conf.h* to send the logs with `printf`.
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## Custom log function
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If you can't use `printf` or want to use a custom function to log, you can register a "logger" callback with `lv_log_register_print_cb()`.
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For example:
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```c
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void my_log_cb(lv_log_level_t level, const char * file, uint32_t line, const char * fn_name, const char * dsc)
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{
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/*Send the logs via serial port*/
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if(level == LV_LOG_LEVEL_ERROR) serial_send("ERROR: ");
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if(level == LV_LOG_LEVEL_WARN) serial_send("WARNING: ");
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if(level == LV_LOG_LEVEL_INFO) serial_send("INFO: ");
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if(level == LV_LOG_LEVEL_TRACE) serial_send("TRACE: ");
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serial_send("File: ");
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serial_send(file);
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char line_str[8];
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sprintf(line_str,"%d", line);
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serial_send("#");
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serial_send(line_str);
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serial_send(": ");
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serial_send(fn_name);
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serial_send(": ");
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serial_send(dsc);
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serial_send("\n");
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}
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...
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lv_log_register_print_cb(my_log_cb);
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```
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## Add logs
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You can also use the log module via the `LV_LOG_TRACE/INFO/WARN/ERROR(description)` functions.
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