Assume that XTAL= 8MHz. Find the TCNT0 value needed to generate a time delay of 5ms. Use Normal Mode, and the largest prescaler possible.

To solve this problem, we need to follow these steps:

1. First, we need to identify the largest prescaler possible. For most AVR microcontrollers, the largest prescaler for Timer/Counter0 is 1024.

2. Next, we calculate the frequency of the timer clock, which is the crystal frequency divided by the prescaler. So, the frequency is 8MHz/1024 = 7812.5 Hz.

3. Then, we calculate the period of the timer clock, which is the reciprocal of the frequency. So, the period is 1/7812.5 = 0.000128 seconds, or 128 microseconds.

4. Now, we can calculate the number of timer clock periods in the desired delay. The desired delay is 5ms, or 0.005 seconds. So, the number of timer clock periods is 0.005/0.000128 = 39.0625.

5. Since the timer count (TCNT0) must be an integer, we round 39.0625 up to 40.

6. Finally, we calculate the TCNT0 value needed to generate the delay. The timer counts up from the TCNT0 value to 255, so the TCNT0 value is 255 - 40 = 215.

So, the TCNT0 value needed to generate a time delay of 5ms with a crystal frequency of 8MHz and a prescaler of 1024 is 215.