hi Richard:
Thanks for your response. Here is my debug test:
1. I create 2 tasks(idle task is not included), And put breakpoint in each of them(in task while(1){} body), So when task running, i can know it.
2. I put a breakpoint in tick interrupt handler, And disable the ' freeze bit ' to make sure it ticks in debug mode.
result
1. This 2 task run just for once. After create idle task. Freertos seems like stop task switch. Just run in idle task.
2. The tick interrupt executing frequently.
So does anything else i have ignored? Or maybe exists any other possibilities?