Keil accurately measures code execution time

In the project settings, under "Debug", select Hardware Simulation on the right, click the drop-down box to select "J-LINK/J-TRACE", and then click "Setting"

In the pop-up window, under "Debug", select "JTAG" or "SW", and then select the download rate.

Click on the Trace tab, if you select SW

Check the "Enable" option, enter the actual working clock frequency of the MCU in the "Core" box (that is, the frequency at which the microcontroller executes instructions, which MDK will use to calculate the time), and then check "Autodetect max SW0 Clock"

If you select "JTAG",

First check "Enable", set the clock frequency in "Core", and finally remove the "Enable" just checked.

Because the "JTAG" mode does not support the "Trace" function, the simulation will report an error if "Enable" is not removed.

Next, click to enter the simulation, and there will be a time window in the lower right corner of the interface

If you right-click the mouse on it, you will see:

The top two are for resetting "t1" and "t2", and the bottom three are for selecting which time to display on the status bar.

"t0" indicates the time from the start of the program to the present, and cannot be reset. The other two can be reset at will, and can be used to measure the running time of a specific function or a line of program.

The specific operation is: add a breakpoint before the code to be tested. When the program runs to the target line, it will stop, then reset "t1" or "t2", and add a breakpoint before the next line of code. Then continue running the program. The program will stop before the next line of code. At this time, the value of "t1" is the running time of the target line program.