#Period counter vhdl serial
#Period counter vhdl full
#Period counter vhdl software
#Period counter vhdl code

Luckily, the software creates most of the test bench itself. In order to verify what I just said, a test bench is generated with the aid of the Xilinx ISE 13.1 software. The reset signal is an essential part in any digital system and its function in this component is to restart the counter. Since the counter begins at zero, the superior limit is 125000 - 1.

#Period counter vhdl serial

Why 124999 and not 250000? A clock signal is a square wave with a 50% of duty cycle (same time active and inactive) for this case, 125000 cycles active and 125000 cycles inactive. at 9:14 PM Using the VHDL ASSERT to give a synthesis error I wrote a counter using serial addition which uses generics to define the number of bits in the counters (which are held in SRL16Es), the period of the counter, and the positions of pulses during the period. The frequency_divider process, lines 16 to 28, generates the 200Hz signal by using a counter from 1 to 124999. The inputs and outputs of the system are declared between the lines 4 through 10. Lines 1 and 2 are equivalent to the C/C++ #include or the Python import statements. if(rst='1')thenĮdit: Post updated with the testbench, RTL Schematic, and Simulation Waveform by Deepak Joshi.Signal counter : integer range 0 to 124999 := 0 įrequency_divider: process (reset, clk_in) begin if (reset = ' 1') thenĮlsif rising_edge(clk_in) then if (counter = 124999) then Signal temp:std_logic_vector(3 downto 0) Īnother distinct yet obvious detail that you need to keep in mind is that since this is a down-counter, its reset state would be at “1111”. library IEEE Ĭount : out STD_LOGIC_VECTOR (3 downto 0)) The ‘temp’ variable signal is a placeholder for the output count. Since we are using a variable signal, we no longer need to declare the ‘COUNT’ output as ‘inout’. The entity architecture pair is just the same as it was for the 4-bit up-counter except for a minor change. Declaring it before initiating the process gives us the chance to use it in other processes. This is kind of like the global declaration concept. The variable signal is declared after the architecture statement. For example, in your FPGA, you have one system clock (clk) going in, but you want to use different frequencies, say clk/4 and clk/2 for different parts of the FPGA. In this example, we introduce the concept of generic into an entity declaration. Once its use is done, we will assign the values to the proper ports. Practical VHDL (4): A Clock Divider by N. The variable signal will be a placeholder for the circuit to remember its previous value. However, the only difference is that here, we will be using a variable signal.

#Period counter vhdl code

Here, we will code an almost similar program to the one above. Technically, we can recycle the code from above and replace COUNT=>COUNT+1 by COUNT=>COUNT-1. We are going to try a little something different over here.

And four outputs since its a 4-bit counter.Įxplanation of the VHDL code for synchronous down counter using the behavioral method.

It has two inputs of STD_LOGIC, Clock and Reset. You can see the logic circuit of the 4-bit synchronous up-counter above. The flip-flops in the synchronous counters are all driven by a single clock input. A VHDL timer is created by counting clock cycles we use the clock period as a. Synchronous means to be driven by the same clock. Counter and Clock Divider A lot of interesting things can be built by. How does the code work? 4-bit synchronous up counter Up-counter Explanation of the VHDL code for synchronous up-counter using behavioral modeling method.

#Period counter vhdl full

Full VHDL code for synchronous up-down counter using the behavioral method.

Explanation of the VHDL code for synchronous up-down counter using the behavioral modeling method.

Full VHDL code for synchronous down counter using behavioral modeling method.

Explanation of the VHDL code for synchronous down counter using the behavioral method.

Full VHDL code for synchronous up-counter using the behavioral method.

Explanation of the VHDL code for synchronous up-counter using behavioral modeling method.