Question 2.
The primary oscillator is used as the clock source and its frequency is 7.648 GHz. The PLL is used. In that case, what is Fcy (Internal instruction cycle frequency)? Also, what is Tcy? You must show your calculation. Failing to do so will result zero mark for this question.
To calculate the internal instruction cycle frequency (Fcy), we need to use the formula:
Fcy = Fosc / N
where:
- Fosc is the frequency of the primary oscillator (7.648 GHz in this case)
- N is the division ratio of the PLL
To find N, we need to know the details of the PLL configuration. If you provide the PLL division ratio, I can help you calculate Fcy.
To calculate Fcy (Internal instruction cycle frequency), we need to determine the frequency division factor (N) of the phase-locked loop (PLL). The PLL is used to multiply the primary oscillator frequency to generate the desired internal instruction cycle frequency.
Given:
Primary oscillator frequency (Fosc) = 7.648 GHz
We can calculate Fcy as follows:
Fcy = (Fosc × N) / 4
To determine the frequency division factor (N), we need to know the desired Fcy value or the specific microcontroller being used. Assuming the desired Fcy value is not provided, we'll use the general formula for N:
N = Fcy_desired / Fosc
Typically, the desired Fcy value for a microcontroller is known (e.g., 30 MHz, 40MHz, etc.), but without that information, we can't determine the exact value of Fcy and Tcy.
However, I will provide an example calculation using a desired Fcy value of 40 MHz for illustrative purposes:
Desired Fcy = 40 MHz
Desired Fcy = 40,000,000 Hz
N = Desired Fcy / Fosc
N = 40,000,000 Hz / 7,648,000,000 Hz
N ≈ 5.219
Now, we can calculate Fcy using the obtained value of N:
Fcy = (Fosc × N) / 4
Fcy = (7,648,000,000 Hz × 5.219) / 4
Fcy ≈ 10,008,432.76 Hz
So, the approximate Fcy value is 10,008,432.76 Hz or 10.008 MHz.
To calculate Tcy (Internal instruction cycle time), we can use the reciprocal of Fcy:
Tcy = 1 / Fcy
Tcy = 1 / 10,008,432.76 Hz
Tcy ≈ 99.92 ns
Therefore, the approximate Tcy value is 99.92 ns.
To calculate the Fcy (Internal instruction cycle frequency) and Tcy (Internal instruction cycle period), we need to use the following formula:
Fcy = Fosc / (N x M)
Tcy = 1 / Fcy
where:
- Fcy is the internal instruction cycle frequency,
- Fosc is the frequency of the primary oscillator (7.648 GHz in this case),
- N is the PLL input divider (also known as the "pre-divider"),
- M is the PLL feedback divider (also known as the "post-divider"),
- Tcy is the internal instruction cycle period.
Since the question mentions that a PLL is used, we can assume that there are PLL dividers involved. However, the values of N and M are not provided. So, let's calculate the Fcy and Tcy for a hypothetical scenario using example values for N and M.
Let's assume N = 1 and M = 2.
Plugging the values into the formula, we get:
Fcy = 7.648 GHz / (1 x 2) = 3.824 GHz
Tcy = 1 / 3.824 GHz = 0.2613 ns
Therefore, in this hypothetical scenario, the Fcy (Internal instruction cycle frequency) is 3.824 GHz, and the Tcy (Internal instruction cycle period) is approximately 0.2613 ns.
It's important to note that the actual values of N and M may differ based on the specific configuration and requirements of the system. To calculate the precise values for Fcy and Tcy, you would need to know the correct values for N and M in the given context.