ST-LINK_V2引脚定义与使用注意事项_SWO

Introduction

The ST-LINK/V2 is an in-circuit debugger/programmer for the STM8 and STM32 microcontrollers. The single wire interface module (SWIM) and the JTAG/serial wire debugging (SWD) interfaces facilitate the communication with any STM8 or STM32 microcontroller operating on an application board.

硬件

JTAG接口针脚布局

我们关注的是STM32，JTAG接口针脚布局见下图，注意缺口位置：

JTAG debugging flat ribbon layout.png

各针脚的名称及功能

Table 4 summarizes the signals names, functions, and target connection signals of the standard 20-pin JTAG flat ribbon.

JTAG_SWD cable connections.png

ST-LINK/V2 status LED 灯光状态信号

The LED labeled ‘COM’ on top of the ST-LINK/V2 shows the ST-LINK/V2 status (whatever the connection type). In detail:

LED is blinking RED: the first USB enumeration with the PC is taking place
LED is RED: communication between the PC and ST-LINK/V2 is established (end of enumeration)
LED is blinking GREEN / RED: data being exchanged between the target and the PC
LED is GREEN: the last communication has been successful
LED is ORANGE: ST-LINK/V2 communication with the target has failed.

几个重要针脚 1、7、9、20

山寨ST-LINK.png

当板子上没有JTAG接口时，我们可以使用SWD接线方式，以前使用盗版的ST-link时，只需要四根线（SWIO,SWCLK,3V3,GND）就可以轻松实现目标板连接，简单小巧，可谓是嵌入式攻城狮的最爱！如果板子有独立供电3V3可以不接，这时只需接三根线就能搞定。

但是换成正版的ST-link/V2，还是四线（SWIO,SWCLK,3V3,GND）连接的话，就会出现No target connected的问题。

ST-LINK No target connected 问题.png

TVCC Target borad VCC，也就是目标板的VCC。用来监测目标板的信号电平，是5V还是3.3V，从而输出相应的调试电平。

所以我们需要连五根线（SWIO,SWCLK,3V3,GND,TVCC），但有的情况下芯片只有四根引脚，只能使用四根线的话，那么可以将3V3和TVCC连接到一起使用，现在可以尽情的使用速度快、性能稳定的正版下载器了！

13针脚 SWO

见注释 “Optional: for Serial Wire Viewer (SWV) trace.” 这是一个调试相关的针脚。

The ITM interface (short for Instrumentation Trace Macrocell) allows the Tracealyzer recorder library to transmit software-generated trace data via the debug probe, either using the SWO pin (Serial Wire Output) which is supported by the regular I-Jet model, or over the ETM trace port if you have an IAR I-Jet Trace. However, SWO on a regular I-Jet gives more than sufficient speed.