{"id":8794,"date":"2016-08-15T05:10:49","date_gmt":"2016-08-15T04:10:49","guid":{"rendered":"https:\/\/sysprogs.com\/w\/?p=8794"},"modified":"2016-08-15T05:10:49","modified_gmt":"2016-08-15T04:10:49","slug":"introducing-the-new-real-time-watch","status":"publish","type":"post","link":"https:\/\/sysprogs.com\/w\/introducing-the-new-real-time-watch\/","title":{"rendered":"Introducing the new Real-time Watch"},"content":{"rendered":"

One of the toughest types of problems faced by embedded software developers is timing problems. Seeing what exactly happened before a problem popped up and being able to put multiple events on one scale could save hours of time. The previous version of VisualGDB included an embedded profiler<\/a> that could\u00a0collect\u00a0statistics on the runtime\u00a0of various functions. VisualGDB 5.2 takes this even further and introduces\u00a0Real-time watch<\/strong> – a framework for convenient recording and visualization of various real-time events in your program\u00a0that\u00a0works out-of-the-box with FreeRTOS and supports non-RTOS environments as well:\"rtw\"<\/a><\/p>\n

<\/p>\n

Supported platforms<\/h2>\n

Real-time watch works with any\u00a0ARM Cortex\u00a0microcontroller that can be debugged with either OpenOCD or Segger J-Link software.\u00a0It consists of a transparent framework that\u00a0sends timing information to VisualGDB over JTAG\/SWD and a\u00a0set of GUI\u00a0in VisualGDB that allows easily selecting what information to collect and presents it in a understandable form.<\/p>\n

Setup<\/h2>\n

We have made Real-time watch extremely easy to setup. Simply go to the Dynamic Analysis page of VisualGDB Project Properties and enable\u00a0it for the event types you want to trace:\"properties\"<\/a>In the pre-release version you will need to add the USE_FREERTOS macro to project properties (if you are using FreeRTOS) and call the initalization function from your main(), but once we\u00a0update our BSPs for the most popular platforms, this will be done automatically.<\/p>\n

Enabling real-time watch will\u00a0automatically add a reference to the Fast Semihosting and Profiler framework:\"framework\"<\/a><\/p>\n

The framework itself won’t\u00a0interfere with your program’s workflow unless you explicitly enable Visual Watch, but enabling it\u00a0will automatically\u00a0activate its full power\u00a0of recording and displaying what is going on in your program.<\/p>\n

Viewing function timing<\/h2>\n

Let’s start with something easy. Create a basic “Blinking LED” project, enable real-time watch in the VisualGDB Project Properties and get a nice graphical representation\u00a0of the\u00a0interrupt handler, delay function and the function that toggles the LED.<\/p>\n

Once you enabled it on the Dynamic Analysis page, simply start a normal debugging session, let it stop at a breakpoint, open the Real-time watch window and add the HAL_Delay<\/strong>, HAL_GPIO_WritePin<\/strong> and SysTick_Handler<\/strong> functions there:\"add\"<\/a><\/p>\n

VisualGDB will automatically do the instrumentation magic and once you hit F5 it will begin plotting the function run time in the real-time watch window:\"blink\"<\/a><\/p>\n

That’s exactly what would expect: HAL_Delay()<\/strong> taking most of the time, HAL_GPIO_WritePin()<\/strong> getting called every 500 ms, timer interrupt firing all the time. The window is fully interactive, so you can zoom in\/out and\u00a0measure precise\u00a0timing of various events:\"zoomin\"<\/a>Tracing every call of a function that gets executed too often can create a considerable overhead, so we made it easy to estimate and manage\u00a0it. First\u00a0of all, the statistics button displays the estimated overhead:\"overhead\"<\/a><\/p>\n

Second of all, VisualGDB goes smart about instrumenting the functions, so if you pause the recording for some of them, or remove them from Visual \u00a0Watch, the overhead will be reduced without restarting your program:
\n\"paused\"<\/a><\/p>\n

Finally, we have automated adding\/removing of functions via presets. Simply save a set of watched functions as a preset and you can get back to recording them any time you want:\"presets\"<\/a><\/p>\n

<\/h2>\n

RTOS integration<\/h2>\n

Real-time watch goes beyond just measuring the function run times.\u00a0It can seamlessly plot various events inside your RTOS:<\/p>\n