DWT, Debug Watchpoint and Trace which usually used for system debugging and tracking
The purpose of this utilities is to achived precision millis and micro second timer with DWT
This utilities provide millis and micro second delay and interval measurement
Delay in HAL/LL is not accurate and there is always additional 1ms delay(refer to below)
There is some discussion on this issue in ST community forum : Here
Delay using HAL_Delay:
Delay using LL_mDelay:
Delay using DwtDelay_ms: