日志输出的后端多样化，可支持例如：串口、网络，文件、闪存等后端形式。
日志输出被设计为线程安全的方式，并支持异步输出模式。
日志系统高可靠，在中断 ISR 、Hardfault 等复杂环境下依旧可用。
日志支持运行期 / 编译期设置输出级别。
日志内容支持按关键词及标签方式进行全局过滤。
API 和日志格式可兼容 linux syslog。
支持以 hex 格式 dump 调试数据到日志中。
兼容 rtdbg （RTT 早期的日志头文件）及 EasyLogger 的日志输出 API。
RT-Thread官方提供了对瑞萨 RA6M4的BSP支持，应用日志模块十分简单，使用RT-Thread Studio创建工程，打开软件包管理器，选中ulog：
打开软件模拟RTC，方便查看系统时间戳：
ulog配置：
连接 UART7 （TX:P613; RX:P614）,波特率 115200。此路串口用于 RT-Thread 系统命令行交互。
终端软件可以看到RTT运行起来了：
测试代码使用自带的demo：
/* * Copyright (c) 2006-2021, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2018-08-02 armink the first version */ #include <stdlib.h> #include <rtthread.h> #ifndef ULOG_USING_SYSLOG #define LOG_TAG "example" #define LOG_LVL LOG_LVL_DBG #include <ulog.h> #else #include <syslog.h> #endif /* ULOG_USING_SYSLOG */ void ulog_example(void) { int count = 0; #ifdef ULOG_USING_SYSLOG openlog("example1", 0, 0); #endif while (count++ < 50) { #ifndef ULOG_USING_SYSLOG /* output different level log by LOG_X API */ LOG_D("LOG_D(%d): RT-Thread is an open source IoT operating system from China.", count); LOG_I("LOG_I(%d): RT-Thread is an open source IoT operating system from China.", count); LOG_W("LOG_W(%d): RT-Thread is an open source IoT operating system from China.", count); LOG_E("LOG_E(%d): RT-Thread is an open source IoT operating system from China.", count); ulog_d("test", "ulog_d(%d): RT-Thread is an open source IoT operating system from China.", count); ulog_i("test", "ulog_i(%d): RT-Thread is an open source IoT operating system from China.", count); ulog_w("test", "ulog_w(%d): RT-Thread is an open source IoT operating system from China.", count); ulog_e("test", "ulog_e(%d): RT-Thread is an open source IoT operating system from China.", count); #ifdef ULOG_USING_FILTER if (count == 20) { /* Set the global filer level is INFO. All of DEBUG log will stop output */ ulog_global_filter_lvl_set(LOG_LVL_INFO); /* Set the test tag's level filter's level is ERROR. The DEBUG, INFO, WARNING log will stop output. */ ulog_tag_lvl_filter_set("test", LOG_LVL_ERROR); } else if (count == 30) { /* Set the example tag's level filter's level is LOG_FILTER_LVL_SILENT, the log enter silent mode. */ ulog_tag_lvl_filter_set("example", LOG_FILTER_LVL_SILENT); /* Set the test tag's level filter's level is WARNING. The DEBUG, INFO log will stop output. */ ulog_tag_lvl_filter_set("test", LOG_LVL_WARNING); } else if (count == 40) { /* Set the test tag's level filter's level is LOG_FILTER_LVL_ALL. All level log will resume output. */ ulog_tag_lvl_filter_set("test", LOG_FILTER_LVL_ALL); /* Set the global filer level is LOG_FILTER_LVL_ALL. All level log will resume output */ ulog_global_filter_lvl_set(LOG_FILTER_LVL_ALL); } #endif /* ULOG_USING_FILTER */ #else /* output different priority log by syslog API */ syslog(LOG_INFO, "syslog(%d) LOG_INFO: RT-Thread is an open source IoT operating system from China.", count); syslog(LOG_DEBUG, "syslog(%d) LOG_DEBUG: RT-Thread is an open source IoT operating system from China.", count); syslog(LOG_WARNING, "syslog(%d) LOG_WARNING: RT-Thread is an open source IoT operating system from China.", count); syslog(LOG_ERR, "syslog(%d) LOG_ERR: RT-Thread is an open source IoT operating system from China.", count); syslog(LOG_INFO | LOG_MAIL, "syslog(%d) LOG_INFO | LOG_MAIL: RT-Thread is an open source IoT operating system from China.", count); syslog(LOG_DEBUG | LOG_DAEMON, "syslog(%d) LOG_DEBUG | LOG_DAEMON: RT-Thread is an open source IoT operating system from China.", count); syslog(LOG_WARNING | LOG_AUTH, "syslog(%d) LOG_WARNING | LOG_AUTH: RT-Thread is an open source IoT operating system from China.", count); syslog(LOG_ERR | LOG_SYSLOG, "syslog(%d) LOG_ERR | LOG_SYSLOG: RT-Thread is an open source IoT operating system from China.", count); if (count == 20) { /* Set log priority mask. Only output ERR and WARNING log. */ setlogmask(LOG_MASK(LOG_ERR) | LOG_MASK(LOG_WARNING)); } else if (count == 40) { /* Set log priority mask. The log which level is less than ERROR will stop output. */ setlogmask(LOG_UPTO(LOG_ERR)); } #endif /* ULOG_USING_SYSLOG */ rt_thread_delay(rt_tick_from_millisecond(rand() % 1000)); } } MSH_CMD_EXPORT(ulog_example, run ulog example)
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