STM32 Embedded

SEGGER_RTT当调试串口输出

jlink，swd，Tracealyzer

Views:  times Posted by elmagnifico on September 3, 2021

Foreword

最近看到有人用 JLink 直接当串口用，发现还不错的样子。

SEGGER_RTT

https://www.segger.com/products/debug-probes/j-link/technology/about-real-time-transfer/

简单说 JLink 连了那么多线，如果不用岂不是浪费。就算用SWD接口也能正常使用。

要使用 RTT 也非常简单，JLink 中自带了需要包含的文件，可能需要解压一下

如图所示，解压以后所有可能需要的文件都在RTT里面

主要就是这么几个文件

SEGGER_RTT.c
SEGGER_RTT.h
SEGGER_RTT_ASM_ARMv7M.S,这个平常不需要，如果是汇编里使用RTT可以加上他
SEGGER_RTT_Conf.h
SEGGER_RTT_printf.c，如果要用printf，需要包含，不用的话，完全可以不要

将需要的文件加入以后，加上头文件，就可以玩耍了。

#include "SEGGER_RTT.h"
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
	// 初始化
	SEGGER_RTT_Init();
	// 将hello world 输出到通道0
	SEGGER_RTT_printf(0, "hello world\n");  
}

用起来就像printf一样

RTT本身可以分通道输出，每个通道里看到的只有相同通道的内容，相当于是一个分包，或者分级输出。

config

需要注意默认的RTT的buffer大小和默认是非阻塞模式的

#ifndef   SEGGER_RTT_MAX_NUM_DOWN_BUFFERS
  #define SEGGER_RTT_MAX_NUM_DOWN_BUFFERS           (3)     // Max. number of down-buffers (H->T) available on this target  (Default: 3)
#endif

#ifndef   BUFFER_SIZE_UP
  #define BUFFER_SIZE_UP                            (1024)  // Size of the buffer for terminal output of target, up to host (Default: 1k)
#endif

#ifndef   BUFFER_SIZE_DOWN
  #define BUFFER_SIZE_DOWN                          (16)    // Size of the buffer for terminal input to target from host (Usually keyboard input) (Default: 16)
#endif

#ifndef   SEGGER_RTT_PRINTF_BUFFER_SIZE
  #define SEGGER_RTT_PRINTF_BUFFER_SIZE             (64u)    // Size of buffer for RTT printf to bulk-send chars via RTT     (Default: 64)
#endif

#ifndef   SEGGER_RTT_MODE_DEFAULT
  #define SEGGER_RTT_MODE_DEFAULT                   SEGGER_RTT_MODE_NO_BLOCK_SKIP // Mode for pre-initialized terminal channel (buffer 0)
#endif

颜log

//
// Control sequences, based on ANSI.
// Can be used to control color, and clear the screen
//
#define RTT_CTRL_RESET                "\x1B[0m"         // Reset to default colors
#define RTT_CTRL_CLEAR                "\x1B[2J"         // Clear screen, reposition cursor to top left

#define RTT_CTRL_TEXT_BLACK           "\x1B[2;30m"
#define RTT_CTRL_TEXT_RED             "\x1B[2;31m"
#define RTT_CTRL_TEXT_GREEN           "\x1B[2;32m"
#define RTT_CTRL_TEXT_YELLOW          "\x1B[2;33m"
#define RTT_CTRL_TEXT_BLUE            "\x1B[2;34m"
#define RTT_CTRL_TEXT_MAGENTA         "\x1B[2;35m"
#define RTT_CTRL_TEXT_CYAN            "\x1B[2;36m"
#define RTT_CTRL_TEXT_WHITE           "\x1B[2;37m"

#define RTT_CTRL_TEXT_BRIGHT_BLACK    "\x1B[1;30m"
#define RTT_CTRL_TEXT_BRIGHT_RED      "\x1B[1;31m"
#define RTT_CTRL_TEXT_BRIGHT_GREEN    "\x1B[1;32m"
#define RTT_CTRL_TEXT_BRIGHT_YELLOW   "\x1B[1;33m"
#define RTT_CTRL_TEXT_BRIGHT_BLUE     "\x1B[1;34m"
#define RTT_CTRL_TEXT_BRIGHT_MAGENTA  "\x1B[1;35m"
#define RTT_CTRL_TEXT_BRIGHT_CYAN     "\x1B[1;36m"
#define RTT_CTRL_TEXT_BRIGHT_WHITE    "\x1B[1;37m"

#define RTT_CTRL_BG_BLACK             "\x1B[24;40m"
#define RTT_CTRL_BG_RED               "\x1B[24;41m"
#define RTT_CTRL_BG_GREEN             "\x1B[24;42m"
#define RTT_CTRL_BG_YELLOW            "\x1B[24;43m"
#define RTT_CTRL_BG_BLUE              "\x1B[24;44m"
#define RTT_CTRL_BG_MAGENTA           "\x1B[24;45m"
#define RTT_CTRL_BG_CYAN              "\x1B[24;46m"
#define RTT_CTRL_BG_WHITE             "\x1B[24;47m"

#define RTT_CTRL_BG_BRIGHT_BLACK      "\x1B[4;40m"
#define RTT_CTRL_BG_BRIGHT_RED        "\x1B[4;41m"
#define RTT_CTRL_BG_BRIGHT_GREEN      "\x1B[4;42m"
#define RTT_CTRL_BG_BRIGHT_YELLOW     "\x1B[4;43m"
#define RTT_CTRL_BG_BRIGHT_BLUE       "\x1B[4;44m"
#define RTT_CTRL_BG_BRIGHT_MAGENTA    "\x1B[4;45m"
#define RTT_CTRL_BG_BRIGHT_CYAN       "\x1B[4;46m"
#define RTT_CTRL_BG_BRIGHT_WHITE      "\x1B[4;47m"

如果在类linux的终端中输出，可以支持带颜色的log信息，结合上面的颜色信息，使用下面的头文件即可。

/*
 * Author: Jayant Tang
 * Email: jayant97@foxmail.com
 */

#ifndef _LOG_H_
#define _LOH_H_
#include "SEGGER_RTT.h"

#define LOG_DEBUG 1

#if LOG_DEBUG


#define LOG_PROTO(type,color,format,...)            \
        SEGGER_RTT_printf(0,"  %s%s"format"\r\n%s", \
                          color,                    \
                          type,                     \
                          ##__VA_ARGS__,            \
                          RTT_CTRL_RESET)

/* 清屏*/
#define LOG_CLEAR() SEGGER_RTT_WriteString(0, "  "RTT_CTRL_CLEAR)

/* 无颜色日志输出 */
#define LOG(format,...) LOG_PROTO("","",format,##__VA_ARGS__)

/* 有颜色格式日志输出 */
#define LOGI(format,...) LOG_PROTO("I: ", RTT_CTRL_TEXT_BRIGHT_GREEN , format, ##__VA_ARGS__)
#define LOGW(format,...) LOG_PROTO("W: ", RTT_CTRL_TEXT_BRIGHT_YELLOW, format, ##__VA_ARGS__)
#define LOGE(format,...) LOG_PROTO("E: ", RTT_CTRL_TEXT_BRIGHT_RED   , format, ##__VA_ARGS__)

#else
#define LOG_CLEAR()
#define LOG
#define LOGI
#define LOGW
#define LOGE

#endif

#endif // !_LOG_H_

花里胡哨得就玩起来了。

上位机

JLinkRTT开头的程序有不少，各有各的作用

  • JLinkRTTViewer，独立可视化界面，连接之后会实时显示内容
  • JLinkRTTClient，终端中显示，无法直接连接，需要先用JLink连接上板子或者是IDE中开启调试以后，才能正常显示
  • JLinkRTTLogger，直接以log文件的形式进行输出

JLinkRTTViewer 看着比较好一点

局限

基本没啥人说这个有啥局限，我就来说一下。

速度有限

由于我之前用过 Tracealyzer ,而如果有注意的话，其实可以看到 Tracealyzer 中直接就包含了下面的三个文件

SEGGER_RTT.c
SEGGER_RTT.h
SEGGER_RTT_Conf.h

而 Tracealyzer 就是以RTT的通道作为实时分析的log输出的。

由于我们系统比较大，Tracealyzer 毫无意外的不能直接输出所有进程的信息，只能分段输出。而这个限制本质上就是RTT本身带来的限制，实际带宽大概是1.5mbps左右（我的环境下），提高SWD的速度可以一定程度上提高带宽，具体要看实际的buffer大小，输出频率等等(总的来说带宽和内存只能二选一)

如果以JLinkRTTViewer来显示，基本可以看到速度过快的时候，JLinkRTTViewer也会提示他只有4KB的缓存，不足以支撑输出速度。

不过由于本身就是拿来做debug用的，最好也不要用在一些速度特别快的场合里。

需要注意的是 RTT 本身和 JLink调试占用的是同一根线，也就是说，要边调试边输出debug信息的话，你就不能太快，得留一部分宽度给 JLink 用。

支持芯片有限

有的系列是不支持的，所以…

内存存储

在开启JLinkRTTViewer 的时候都有让选择过控制块在哪里，其实就是说对应的Buffer存储在了哪里。如果只有一片内存之类的可能问题不大，但是对于内存有多片，而且有一些特殊划分之类的，这里就需要制定以下具体的内存位置。

// This can be used to place the RTT control block in the right memory range, if no found automatically.
// This example is for NXP LPC54018, needs to be adapted for each MCU family.
//#define SEGGER_RTT_SECTION ".data.$RAM2"

同理，他的优先级设置也是，默认是最高的，所以他能在中断中使用

//
// Target is not allowed to perform other RTT operations while string still has not been stored completely.
// Otherwise we would probably end up with a mixed string in the buffer.
// If using  RTT from within interrupts, multiple tasks or multi processors, define the SEGGER_RTT_LOCK() and SEGGER_RTT_UNLOCK() function here.
// 
// SEGGER_RTT_MAX_INTERRUPT_PRIORITY can be used in the sample lock routines on Cortex-M3/4.
// Make sure to mask all interrupts which can send RTT data, i.e. generate SystemView events, or cause task switches.
// When high-priority interrupts must not be masked while sending RTT data, SEGGER_RTT_MAX_INTERRUPT_PRIORITY needs to be adjusted accordingly.
// (Higher priority = lower priority number)
// Default value for embOS: 128u
// Default configuration in FreeRTOS: configMAX_SYSCALL_INTERRUPT_PRIORITY: ( configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )
// In case of doubt mask all interrupts: 1 << (8 - BASEPRI_PRIO_BITS) i.e. 1 << 5 when 3 bits are implemented in NVIC
// or define SEGGER_RTT_LOCK() to completely disable interrupts.
//

Summary

总的来说好用还是非常好用的

Quote

https://blog.csdn.net/a369000753/article/details/51192707/

https://zhuanlan.zhihu.com/p/163771273

https://www.cnblogs.com/chen0207/p/12641055.html

CATALOG
    FEATURED TAGS
    RaspberryPi 嵌入式 Git 脚本 python LeetCode C++ APM FreeRTOS Markdown Embedded Linux Vim Ubuntu Tools STM32 Maya LPWAN Graph Theory Algorithm PathFind OMPL VPS QT Router JS Chrome Tampermonkey API Java Spring MySql Springboot Docker V2ray TTRSS Nintendo Switch Trace Crack BLHeli DSHOT ESC Music C# EasyCon Blog 杂谈 Proxy NAS 群晖 ZeroTier Typora Map Log JSON Cython Equip Goods Share DMX512 Blender Game AP Network CloudFlare DIY WIFI Camera Diablo Sensor SES QQ Bot Python Vmq Jenkins ESP32 Software C MT793x NXP CH32 OpenWrt Onion Copilot Investment ChatGPT Debug RouterOS Mikrotik Drone OpenAI 米家
    FRIENDS