I have a K64 project with multi-task using FreeRTOS, I noticed that some of tasks I can make BPs and step into it for debugging and MCUXpresso works properly, but some of the tasks I can make BP and the SW execution will stop at the BP but there is no any indication at all, so I am not able to do anything. I am using Tera Term to monitor system working condition so I know how the system is working.
If I suspend the program running (clicking the yellow double-bar button), I will get a warning of "Interrupt failed". At this point, if I click on Task List for Kernel Awareness, there is nothing come out. There is no interrupt handling in these tasks and it happens repeatably 100% even with single BP in the project.
Figure 1. Normal BP setting
Figure 2. Task stopped with not indication
After finished preliminary testing and debugging of my project on a brand new custom board, I am able to investigate the BP No Indication issue further, and here is the update:
First thing I have done was to check all the static tasks in the project to see which ones were having the issue, the result indicated that there were only two tasks presented the issue. For the two tasks, one handles most of IOs in the system and another one handles all the control related activities, they were the most important tasks in the system and had higher priorities than rest of the tasks, and they were the tasks that I really needed to use Breakpoints and Step-Through functionalities for testing and debugging. With the assistance of a set of terminal VT100 screens and a log system I developed, I was able to finish the testing and debugging the project.
Compared the two tasks with the rest from implementation aspect, nothing standout, then I looked over the task properties, noticed these two tasks have priorities 11 or 14, while other no issue tasks had their task priorities lower than or equal to 10.
In FreeRTOSConfig.h file, I had defined the MAX task priority(configMAX_PRIORITIES) as 16, so I can set task priorities between 1 to 15 in the project. As I had seen in the debugging and testing, all the tasks, including the two tasks with the given task priorities, worked just fine. Please refer to the screenshot attached:
Note: The runtime is recorded as a task has waken up and done something.
Note: task 7 is an event driven task, it is only idle in normal operation.
For testing purpose, I lowered the priorities of the two tasks to 9 or 10, and found out the BPs set in these tasks worked just fine.
Also, I imported a couple of SDK projects, and changed their MAX priority level to 16 and changed the task’s priority level to 15, and found they both worked fine without the BPs issue seen in my project.
These two tasks are the tasks that use periodic timer plus event driven to wake up, I thought the issue may be related to the timer’s interrupt level priority, so I changed the priority of a no issue task which is waked up by event only, the testing shown the issue existed. So it is only related task's priority.
The magic number 10 seems to me are related to project setting in MCUXpresso, but cannot find anything related to that.
For now with the IDE and PE Multilink, I can set the tasks’ priority to 10 or less for debugging if I need to, then recover the tasks priorities later.
