Learn Verilog by Example

This one is going to be a quick easy project. The objective here is to get use the 7-segment LED display on the board to display a scrolling text. it should be slow enough so that it can be easily read. I have made the delay between each word shift to be 1 second. This is long enough to read the text comfortably without missing anything. I have explained in my previous post how to create an accurate delay using verilog, you can read about it there: Create accurate delay in Verilog . Now since I need a 1 second delay here the counter monitoring this count must count to 50,000,000. And the register needed to hold this count must be 29 bits wide. Using this method you can scroll and display anything. Here I have chosen to display the text "Hello There" to scroll across the LED's and appear to be continuous without any stops. The concept is pretty simple. I create a separate counter that increments every time a count of 50,000,000 is reached. This counter will count till

A FIFO(First in First Out) buffer is an elastic storage usually used between two subsystems. As the name indicates the memory that is first written into the FIFO is the first to be read or processed. A FIFO has two control signals i.e. write and read. When write is enabled data is written into the buffer and when read is enabled data is "removed" from the buffer to make room for more data. This concept of write and read (remove) can be best understood from the conceptual diagram of a FIFO below: As can be seen, once the data is read, it can be considered as removed and thus allowing more data to be written into the buffer. Implementation of FIFO in Verilog To implement FIFO in verilog imagine the memory components to be arranged in a circular queue fashion with two pointers; write and read . The write pointer points to the start of the circle whereas the read pointer points to the end of the circle. Both these pointers increment themselves by one after each read or wr