keil no debug unite is selected

This error message typically occurs when you try to start a debug session in Keil without selecting a debug unit. To resolve this issue, follow these steps:

1. In the Keil IDE, go to the "Project" menu and select "Options for Target."

2. In the "Target" tab, select the "Debug" category.

3. Under the "Use" section, select the appropriate debug unit for your target hardware. This may be a hardware debugger like J-Link or a simulator like the Keil Simulator.

4. Click "OK" to save your changes.

5. Now you can start a debug session by clicking on the "Start/Stop Debug Session" button in the toolbar or by pressing F5 on your keyboard.

If you still encounter issues, make sure that your target hardware is properly connected and powered on. You may also need to check your debug settings and make sure that they are configured correctly for your specific hardware.