Verilog: Dual Seven Segment Display Driver

This is an expansion upon my SevenSegmentDisplayDriver module which will allow you to drive a dual seven segment display, specifically the add-on for the Spartan 3E but it should be quite easy to modify for other FPGA’s. The basic premise of this module is you have a dual seven segment display which activates the left or right display depending on whether the enable signal is high or low. So using the code below, when the clock signal is low (right display is active) we send the lower four bits of our number to the display so they show on the right hand side display. When the clock is high (left display is active) we send the upper four bit to the left hand display. By doing this a few hundred times a second both numbers apear be on the display at once. To use this module you must slow down the clock to an appropriate rate and assign it to the enable pin for the display and the CLK input on this module. bIn in the 8-bit number you wish to display and ssOut is the array of segments for the seven segment display (See the SevenSegmentDisplayDriver post for more details) Continue reading

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Verilog: n-Bit Adder

This is code is for an simple asynchronous wrapping n-bit adder. By changing the value of n you can make it a 2, 4, … bit adder where n = <number of bits> – 1. f is the output register that will have the current value of the counter, cOut is the carry output. a & b are the number inputs and cIn is the carry input. Both the number outputs and inputs are set by the value of n so you can add two n-bit numbers and a carry bit then get an n-bit number plus carry bit out. Continue reading

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State Machine for the Spartan 3E Knob (Rotary Encoder)

The following code is a simple state machine that determines the direction that the knob on the Spartan 3E is turning and outputs a clock signal (Count) as it turns. A & B are the inputs from the encoders on the knob, RST & CLK are the reset and clock obviously. Count is the clock signal that goes two cycle for each click of the knob. Dir is the current direction of the knob, 0 for clockwise and 1 for counter-clockwise. Be sure to de-bounce the A & B inputs from the knob as they will have lots of noise and cause the state machine to be unstable. Continue reading

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