avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00

This error message indicates that avrdude, a software tool used for programming AVR microcontrollers, is not able to communicate with the programmer. There are several possible causes for this error, including:

1. Incorrect programmer settings: Ensure that the programmer is properly connected to the computer and that the correct port and settings are selected in the avrdude command.

2. Faulty connections: Check all connections between the programmer and the target device, including power supply, ground, and data lines. Make sure that all pins are properly connected.

3. Incorrect fuse settings: If the target device has incorrect fuse settings, it may not respond to programming commands. Check the fuse settings and make sure they are correct for the target device.

4. Damaged hardware: There may be damage to either the programmer or the target device that is preventing communication. Try using a different programmer or target device to see if the issue persists.

5. Wrong clock speed: Ensure that the clock speed of the target device is correctly set in the avrdude command. If the clock speed is too high or too low, the device may not respond.

Overall, the best way to troubleshoot this error is to systematically check all connections and settings, and eliminate possible causes one by one.