When I started working with VHDL and FPGAs, the first ever project that came to my mind was blinking an LED. But since we all know that most of the development boards have high frequency clocks from around 20MHz to as high you can get. So if we directly connect that clock to LED the blink rate will be so high that it will not be visible to our naked eye.

To blink an LED the simplest method is dividing a clock. I have used a simple counter which counts up to certain maximum value and flips the output signal. For this project I am using Altera DE-1 board. Following is the logic to blink an LED.

This is a clock divider code, just set the max-count value as per your requirenment.

For ex. If I want 1Hz freq. set the max count to i/p freq value viz. 1sec = 1Hz

Then, to get time period of 1sec i.e. 1 Hz frequency set max-count to 240000 as shown below:

1sec = 24000000 -- for i/p frequency of 24 MHz

To get your desired frequency just calculate the maxcount with the formula given below:

max_count = 24000000 * (1/your required frequency)

Code:

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