3-bit synchronous counter 3-bit synchronous counter amisophie (TechnicalUser) (OP) 19 May 06 23:44. VHDL: (vcom-1136: std_logic_vector undefined) syntax,vhdl. This blog post is part of the Basic VHDL Tutorials series. Hey there people, I am just working on this lab. Eight-bit register with enable and asynchronous reset 342 15. Verilog code for a 4-bit unsigned up/down counter with an asynchronous clear module counter (clk, clr, up_down, qout); input clk, clr, up_down; output [3: 0] qout; reg [3: 0] temp; always @. all; entity counter is Port ( rst,clk : in STD_LOGIC; up: in bit; z : out STD_LOGIC_vector( 2 downto 0 )); end counter; architecture Behavioral of Counter is signal zint: STD. Open a new VHDL Device Design file (File > New) by highlighting VHDL File. In a counter, the destination and first operand is a signal or variable and the other operand is a constant equal to 1: 4-bit Unsigned Up Accumulator with Asynchronous Clear Data Input. Go to top Go to VHDL index. The counter has two modes: binary and decade. An up/down counter is written in VHDL and implemented on a CPLD. This type of counter can be constructed only with flip-flops. library ieee; use ieee. 5 : Asynchronous Up-Down Counter In certain applications a counter must be able to count both up and down. Then we can see that the output from the D-type flip-flop is at half the frequency. Synchronous counters can also be implemented with hardware finite state machines, which are more complex but allow for smoother, more stable transitions. It counts up or down depending on the status of the control signals UP and DOWN. We used VHDL to build a 24 bit counter with two inputs--Clock and Reset--and 8 outputs to represent the time in tens of milliseconds. Asynchronous counter circuit design is based on the fact that each bit toggle happens at the same time that the preceding bit toggles from a "high" to a "low" (from 1 to 0). Counters Design in VHDL. The circuit is special type of shift register where the complement output of the last flipflop is fed back to the input of first flipflop. 1 Synchronous Counter 10. Verilog code for counter with testbench Verilog projects, VHDL projects // Verilog code for up counter with testbench // Testbench Verilog code for up counter module upcounter_testbench(); reg clk, In this V erilog project , Verilog code for a 16-bit RISC processor is presented. 3) VHDL Code 4-bit Up Counter with Enable and Asynchronous Reset : library IEEE; use IEEE. When we deal with FPGA, the most used counters are the binary counter. Asynchronous 4-bit DOWN counter. · Implement comparator that compares two 2-bit numbers A and B. Edit, save, simulate, synthesize SystemVerilog, Verilog, VHDL and other HDLs from your web browser. (c) Reset, then count up five more pulses. Asynchronous Counters. all; use ieee. 4 Bit Binary Synchronous Reset Counter Verilog Code. Here Q0 depend on clock hence change when clock goes from 0 to 1 or at positive clock edge. I need it to be Up'/Down = 0 then the circuit should behave as an up counter. The block diagram of 3-bit Asynchronous binary down counter is shown in the following figure. Verilog code for a 4-bit unsigned up accumulator with an asynchronous clear. You must be logged in to read the answer. Clock input of flip-flop 1 (FF1) is driven by external clock pulses while those of the second and third (FF2 and FF3) are driven by respectively. 5 — 13 August 2019 Product data sheet 1. The task is to write a VHDL module that implements a 4 bit counter that can count up and down. Asynchronous Up-Counter with T Flip-Flops Figure 1 shows a 3-bit counter capable of counting from 0 to 7. What Is a VHDL Test Bench (TB)? • VHDL test bench (TB) is a piece of code meant to verify the functional correctness of HDL model • The main objectives of TB is to: 1. Behavioral Verilog code using Boolean equations to implement the FSM control logic procedure of your 4-bit Up/Down Counter FSM design. Verilog Codes for different COUNTERS Verilog code for a 4-bit unsigned up counter with asynchronous clear. These are the following steps to design a 4 bit synchronous up counter using T flip flop: Step 1: To design a synchronous up counter, first we need to know what number of flip flops are required. To change the modulus of the counter we just assign a new value to that constant. You will model several ways of modeling registers and counters. This is a treasure box of blogs and your folks are like leprechauns! Phenomenal read on VHDL code for BCD to 7-segment display converter! We have a t2. There are four basic steps to using the development kit. The VHDL Cookbook First Edition Peter J. The inputs are a clock signal CLK, enable EN, U that determines if the counter counts up or down, and an active low asynchronous reset ClrN. We have to take care of some things, such as the VHDL code may have some non-synthesizable snippets, take care of FPGA constraints etc. The counter should also have an asynchronous active-low preset signal PreN that sets all flip-flops to 1. Verilog HDL: Counter with Asynchronous Reset This example describes an 8-bit counter with asynchronous reset and count enable inputs in Verilog HDL. And four, load the project to the development kit. The counting output across four output pin is incremental from 0 to 15, in binary 0000 to 1111 for 4-bit Synchronous up counter. Here Q0 depend on clock hence change when clock goes from 0 to 1 or at positive clock edge. When found, the 16x baud counter is reset, which re-aligns the baud ticks with the start bit. The block diagram of 3-bit Asynchronous binary down counter is shown in the following figure. General description The 74HC191 is an asynchronously presettable 4-bit binary up/down counter. VHDL CODE FOR D-FLIPFLOP USING WAIT STATEMENTS; VHDL CODE FOR CONVERTERS; VHDL Code for Synchronous and Asyncronous counter; VHDL CODE for 8 bit comparator using two 4 bit c Package body Declaration in VHDL February (1) 2013 (5) August (5). From Wikibooks, open books for an open world VHDL for FPGA Design. VHDL Code For Up-Counter. Here Q0 depend on clock hence change when clock goes from 0 to 1 or at positive clock edge. Operation: A 2-Bit Asynchronous Binary Counter Fig1-1 shows a 2-bit counter connected for asynchronous operation. 74HC191D - The 74HC191 is an asynchronously presettable 4-bit binary up/down counter. 4 Synchronous Up/Down Counter - Behavioral Model163 only what you need to know to quickly get up and running in VHDL. An up/down counter is written in VHDL and implemented on a CPLD. In this diagram, "start" is an input which tells the system to start the. The diagram of a 2-bit asynchronous counter is shown below. VHDL Operator Operation + Addition - Subtraction * Multiplication* / Division* MOD Modulus* REM Remainder* & Concatenation - used to combine bits. 2 LCALL DELAY CLR P3. For this reason, the final circuit below includes an output carry bit. For a ripple up counter, the Q output of preceding FF is connected to the clock input of the next one. The falling edge of the start bit is always sampled at the system clock, in my case, 50MHz. Verilog code for a 4-bit unsigned up counter with an asynchronous clear and a clock enable. My implementation consistis of using a control variable ctrl so when it's 0, the counter counts in ascendant order, else in descendent one. (c) Reset, then count up five more pulses. counter circuit will very quickly ripple from 0111 to 0110 to 0100 to 0000 to 1000, or from 7 to 6 to 4 to 0 and then to 8. 2 Asynchronous Counter 10. synchronous 4-bit decade counter with asynchronous clear: 74LS160A. library ieee; use ieee. of f/f required for Mod-7counter = log27 = 3 f/f Example: Write VHDL code for 4-bit up counter Down counter Example: A three bit down-counter using T flip flop. Lab 3 - Design of a 4-bit Even-Odd Up/Down Counter. std_logic_1164. 1i with VHDL codes. Again, this allows for initial commands as well as easily breaking up the 16 bit incoming data. check it it is synthesisable and it will work this is 3 bit up counter library. Asynchronous Load (active High) D[3:0] Data Input. 1 Designing Gray-Code Counters 2. ARM assembly code to find number of odd numbers in an array ARM Assembly code to find number of even numbers in an array 8051 Program to add two 16 bit Numbers (AT89C51) Microcontroller. Last time, several 4-bit counters including up counter, down counter and up-down counter are implemented in Verilog. (5) 2> Explain the working of a 3-bit asynchronous down counter? (6) 3> What is the clock frequency in mod-8 counter, i) If the period of the waveform at C(which is MSB) is 24microsec? ii) If the period of the waveform at A(which is LSB) is 18microsec? (2) 4> Explain the working of a 3-bit asynchronous up-counter along with truth table and. 9 10 Truncated Counters 2 A 4-bit mod 12 UP counter that counts from 0000 to 1011 is an example of a truncated counter. 2 LCALL DELAY SJMP UP. Sign up to get notified when this product is back in stock. This example is a 4-bit down counter with a synchronous set. of counters: asynchronous and synchronous counters. An up/down counter is written in VHDL and implemented on a CPLD. because i had design the ckt but i don't know how to write code for this ckt. 2 Design of Synchronous Counter Using T Flip-Flops 7. What is an asynchronous counter? In an asynchronous counter, all the clock inputs of the flip-flops have a unique input that is not shared with any other flip-flop in the system. VHDL Code: library IEEE; Asynchronous Up counter using T- Flipflop. This is almost similar to ring counter with a few extra advantages. This VHDL program is a structural description of the interactive Full-Adder on teahlab. We will write the VHDL code for all the three types of synchronous counters: up, down, and up-down. std_logic_1164. 4 Synchronous Up/Down Counter - Behavioral Model161 12. A Johnson counter is a digital circuit with a series of flip flops connected together in a feedback manner. My VHDL code normally handles a few transitions (hence states) Idle/waiting-> if the data input is low,-----> the baud counter is initialised to half a bit period and goto state 2; START bit validation : decrement the baud counter-> if data input is 1 then return to state 1 else. Write VHDL code for the following counters i) 4 bit asynchronous up counter ii) 4 bit synchronous up counter iii) 4 bit synchronous up/down counter with a control input up/down. std_logic_unsigned. Four different VHDL up/down counters are created in this tutorial: Up/down counter that counts up to a maximum value and then wraps around to 0. With size of gray counter the vhdl code length increases which in any case is not feasible. The circuit can store one bit and can counter from zero to one before it overflows. 7 BCD to 7-Segment Decoder - Data-Flow Model168. 3 8-Bit Register with Load Enable - Behavioral Model165 13. In such a case, the generation parameter and its scope of values are generated in similar way as in the sequential loop statement. I based this on an. Finite state machines: counter Use FSM to implement a synchronous counter 2-bit (mod 4) counter starts at 00 counts up to 11 resets to 00 after 11 Finite state machine state (q): 2 bits, initially 00 output (z): same as state input x = 0: same state x = 1: increment Usage Keeping track of number of bits sent Program counter (PC). The test bench program used for testing the design is given below. The circuit below is a 3-bit up-down counter. You could use a smaller counter and add padding, but that just adds more work. sch entity Sub Logic one is port (nnout L1 : out bit ); end. External clock pulse is connected to all the flip flops in parallel. The lpm_counter megafunction is a binary counter that features an up, down, or up/down counter with optional synchronous or asynchronous clear, set, and load ports. It has asynchronous clear which is used to stop the counter. ALL; use ieee. We used VHDL to build a 24 bit counter with two inputs--Clock and Reset--and 8 outputs to represent the time in tens of milliseconds. Implement Program Counter Vhdl Code For Seven. From Logo to Python in Two Decades. Q[3:0] Data Output. If there is no matching number for count in the case statement, then the default pattern is displayed which is all the LEDs off as shown in this line of code: when others => LED <= not "00000000"; Every case statement in VHDL must have a default value using the VHDL others keyword. Hence a 3-bit counter is a mod-8 counter. Building an 18-Bit AND This is one way… Synthesizers are good at building structures like this from lower-level building blocks. The scaling factor. STD_LOGIC_1164. A Johnson counter is a digital circuit with a series of flip flops connected together in a feedback manner. VHDL PaceMaker is a self-teach tutorial that gives you a great foundation in the basics of the VHDL language. This is a synchronous modulus 100 Up counter. Loading Toggle navigation Run You may wish to save your code first. So you turn the output on when the counter overflows and turn it off when bit three gets set the first time. The falling edge of the start bit is always sampled at the system clock, in my case, 50MHz. VHDL for FPGA Design/4-Bit BCD Counter with Clock Enable. all; use ieee. My VHDL code normally handles a few transitions (hence states) Idle/waiting-> if the data input is low,-----> the baud counter is initialised to half a bit period and goto state 2; START bit validation : decrement the baud counter-> if data input is 1 then return to state 1 else. vhd which contans your own VHDL code with a description of the logic circuit architecture shown in Figure 2. Finite state machines: counter Use FSM to implement a synchronous counter 2-bit (mod 4) counter starts at 00 counts up to 11 resets to 00 after 11 Finite state machine state (q): 2 bits, initially 00 output (z): same as state input x = 0: same state x = 1: increment Usage Keeping track of number of bits sent Program counter (PC). 2: Standard VHDL Mathematical Packages IEEE Computer Society Document IEEE 1076. VHDL Code for 4-Bit Aynchronous Accumulator. Whereas for the up-down counter, you can use multiplexers as switches as we saw in the design of the 3-bit synchronous up-down counter. It is simple modification of the UP counter. General description The 74HC191 is an asynchronously presettable 4-bit binary up/down counter. Signals are for connecting modules One source of this confusion is that vhdl signals (or verilog wires) are only strictly needed to wire up entity/module instances in a structural design. VHDL: Counter with Asynchronous Reset. Instantiate the design under test (DUT) 2. VLSI Design & Implementation of Asynchronous FIFO using FPGA with Verilog/VHDL code. The significance of using JK flip flop is that it can toggle its state if both the inputs are high, depending on the clock pulse. 4-bit Unsigned Up Counter with Asynchronous Load from Primary Input IO Pins Description C Positive-Edge Clock ALOAD Asynchronous Load (active High) D[3:0] Data Input Q[3:0] Data Output VHDL Code Verilog Code library ieee; use ieee. Build a 2-bit Asynchronous Counter. As there is a maximum output number for Asynchronous counters like MOD-16 with a resolution of 4-bit, there are also possibilities to use a basic Asynchronous counter in a configuration that the counting state will be less than their maximum output number. The project we bu. Output of FF0 drives FF1 which then drives the FF2 flip flop. Seems like I won the lottery here…. 3bit_counter. vhd to identify your VHDL code. Figure 9--38 Two cascaded counters (all J and K inputs are HIGH). A counter may count up or count down or count up and down depending on the input control. std_logic_unsigned. Synchronous Counter does not produce any decoding errors. We have to take care of some things, such as the VHDL code may have some non-synthesizable snippets, take care of FPGA constraints etc. Every VHDL counter is a modulo counter. synchronous 4-bit decade counter with asynchronous clear: 74LS160A. VHDL Code: library IEEE; Asynchronous Up counter using T- Flipflop. A 5-bit asynchronous binary counter is made up of five flip-flops, each with a 12 ns propagation delay. You might have a good reason for asynchronous reset, but if not, synchronous reset is a better habit. I'm building some modules in VHDL for handling modular arithmetic and want to make sure it's well-designed for timing and somewhat efficient when scaling up. Bit up/down counter with load able count. That is, as opposed to hard-coding a bit/hex literal - even if you for some reason hard-code the width as you have done, (others => '0') is more standard in this case. This is a simple explanation of VHDL code for 3 bit asynchronous counter using jk flip-flop in Vivado 2016. The test suite shown in fig. Asynchronous counter circuit design is based on the fact that each bit toggle happens at the same time that the preceding bit toggles from a “high” to a “low” (from 1 to 0). This is a synchronous modulus 100 Up counter. 4 bit multiplier vhdl code behavioral 4 bit multiplier vhdl code behavioral. Ripple Counter: Ripple counter is an Asynchronous counter. 1 Synchronous Counter 10. TEXT EDITOR--library ieee; VHDL code for 4-bit Asynchronous binary Up-Counter DBMS Practical Ex-3 October (7). You must be logged in to read the answer. 2 Asynchronous Counter 10. An 'N' bit Asynchronous binary down counter consists of 'N' T flip-flops. The counter increments itself on the rising edge of the clock input, and sets itself asynchronously to 0 when it receives a high reset. LaMeres [email protected] Fig 1-4Propagation delays in a 3-bit asynchronous (ripple-clocked) binary counter. A test suite for a 4 bit Gray counter with enable and asynchronous reset. std_logic_1164. For example, if the present count = 3, then the up counter will calculate the next count as 4. Asynchronous FIFOs and DRAMs in particular. Language Structure VHDL is a hardware description language (HDL) that contains the features of conventional programming languages such as Pascal or C,. The use of the keyword “downto” in every bit vector definition is tedious. Write VHDL code for johnson counter 3. The simplest circuit is the asynchronous one where the inverted output (/Q) from one stage feeds the clock pulse input (CK) of the following stage. vhd with the following content: -- fourbit_counter. 8 Code Converters 7. Design of 4 to 2 Encoder using. 3-bit binary up/down ripple counter. How can we change the code to get this to occur? So here's the code for shift register. all is also required before the entity, like: library IEEE; use IEEE. Here is the code for a 3 bit Synchronous counter. VHDL Example: A Four Bit Up-counter Resetn: Reset input E: enable input In the architecture body the flip-flops in the counter are re presented by the signal na med Count If E=1, the count is incremented If E=0, the code explicitly assig ns Count<=Count The O outputs are assigned the values of Count at the en d fo the code. But, I'm tasked with making a 3-bit and 5-bit counter out of D-Flip Flops and various logic gates. Verilog code for 16-bit. 3bit_counter. Let’s take a look at implementing the VHDL code for synchronous counters using behavioral architecture. The lpm_counter megafunction is a binary counter that features an up, down, or up/down counter with optional synchronous or asynchronous clear, set, and load ports. } Yes, I was running the code as the top module of my project. So If the reset is 1 you reset the counter, else if a rising edge on the clock you want to. For example, rule VER_1_3_2_1 is described in the STARC documentation for Verilog Design Style Guide, section 1 (basic design constraint), subsection 1. How do you design 4 bit asynchronous UP counter. The Even-Odd Up/Down counter has a clock input, clk, a reset input, rst, count enable input, cen, and an up/down control input, dir. The VHSIC stands for Very High Speed Integrated Circuit. The clock inputs. For the purposes of this tutorial, we will use the example VHDL code shown below. Four different VHDL up/down counters are created in this tutorial: Up/down counter that counts up to a maximum value and then wraps around to 0. We will allow binary encoding of the counter. Figure 12-69 is a 4-bit up-counter with asynchronous Reset and Parallel Load features. The Gray code counter used in this design is “Style #2” as described in Cliff Cumming’s paper. About This Manual XST User Guide v Data Book Pages from The Programmable Logic Data Book, which contains device- specific information on Xilinx device characteristics, including readback, boundary scan, configuration, length count, and debugging. It contains four master/slave flip-flops with internal gating and steering logic to provide asynchronous preset and. widely used sequential circuits. 1 VHDL Design Units One unique property of VHDL compared to other hardware languages is the concept of the Design units. For a ripple up counter, the Q output of preceding FF is connected to the clock input of the next one. Digital System Design with FPGA: Implementation Using Verilog and VHDL, 1st Edition by Cem Unsalan and Bora Tar (9781259837906) Preview the textbook, purchase or get a FREE instructor-only desk copy. Whereas for the up-down counter, you can use multiplexers as switches as we saw in the design of the 3-bit synchronous up-down counter. all; use IEEE. • Your project should have the following ports: • Clock_System (1 Bit input signal) • Reset (1 Bit input signal) • Write the VHDL code that describes the One Hot up counter behavior displayed to 6 LEDs with an asynchronous reset switch to start the counter over at 000001. One, set up the directories to hold the project. The count sequence usually repeats itself. Output of FF0 drives FF1 which then drives the FF2 flip flop. As there is a maximum output number for Asynchronous counters like MOD-16 with a resolution of 4-bit, there are also possibilities to use a basic Asynchronous counter in a configuration that the counting state will be less than their maximum output number. We will write the VHDL code for all the three types of synchronous counters: up, down, and up-down. 3-Bit UP / DOWN Counter ( Structural ) with Test Bench Program FULL ADDER using Two HALF ADDERS and One Or gate (STRUCTURAL) 64 x 1 MULTIPLEXER using 8 x 1 multiplexer (Structural) with the help of "GENERATE". VHDL Code Following is the VHDL code for a 4-bit unsi gned up accum ulator with asynchronous clear. Please note that these codes are only for your reference, NOT 4-bit Up Counter with Enable and Asynchronous Reset CS/EE120A VHDL Lab Programming Reference. 8 bit leading zero count vhdl program? 4 bit Synchronous UP counter. / VHDL: Counter with Asynchronous Reset. The asynchronous CLR, when High, overrides all other inputs and sets the Q output Low. The following code is designed using Xilinx ISE 7. std_logic_unsigned. 3-Bit UP / DOWN Counter ( Structural ) with Test Bench Program FULL ADDER using Two HALF ADDERS and One Or gate (STRUCTURAL) 64 x 1 MULTIPLEXER using 8 x 1 multiplexer (Structural) with the help of "GENERATE". The concepts of test suite and testbench will thus have to be refined in numerous ways in 5. 5 Shift Register with Synchronous Parallel Load - Behavioral Model166 13. It is simple modification of the UP counter. Clock pulses are fed into the CK input of FF0 whose output, Q 0 provides the 2 0 output for FF1 after one CK pulse. This page contains VHDL tutorial, VHDL Syntax, VHDL Quick Reference, modelling memory and FSM, Writing Testbenches in VHDL, Lot of VHDL Examples and VHDL in One Day Tutorial. In this case, we assign an integer value to a constant called modulus. For a ripple up counter, the Q output of preceding FF is connected to the clock input of the next one. Notice that in creating a 4-bit counter, you have incidentally created a 1-bit, 2-bit, and 3-bit counter along the way. synthesis tool will just tied to gnd or vcco depends upon value or infer LUTs to store this value. The block diagram and truth table of 4 Bit Binary Synchronous Reset Counter Verilog Code is also mentioned. Asynchronous Counter. because i had design the ckt but i don't know how to write code for this ckt. The project we bu. micro instance (built from amzn-ami-hvm-2016. A counter is a common component in VHDL design. Verilog HDL: Counter with Asynchronous Reset This example describes an 8-bit counter with asynchronous reset and count enable inputs in Verilog HDL. The outputs to the clock will be a binary number from 0000-1001 (0 to 9 decimal). 4 bit multiplier vhdl code behavioral 4 bit multiplier vhdl code behavioral. 1 Up/Down Binary Counter 2. 2 LCALL DELAY CLR P3. Projects using Quartus II v7. My implementation consistis of using a control variable ctrl so when it's 0, the counter counts in ascendant order, else in descendent one. Right click on the desired. Here's the D Flip Flop code (which was tested and works):. (c) Reset, then count up five more pulses. This is a simple explanation of VHDL code for 3 bit asynchronous counter using jk flip-flop in Vivado 2016. Simplified 4-bit synchronous down counter with JK flip-flop. Examine the count sequence in binary, starting from 5: 0. INDEX Absorption Property, 26 access types, 52 analog signal, 1 AND, 27, 56 AND array, 4 AND gate, 4, 35, 76, 155, 156 AND plane, … - Selection from Introduction to Digital Systems: Modeling, Synthesis, and Simulation Using VHDL [Book]. std_logic_unsigned. Any hints how it is going to be represented. In asynchronous counter, a clock pulse drives FF0. Counters- Updown counter 4bit testbench 4 BIT UPDOWN COUNTER TESTBENCH UP DOWN COUNTER module updowncounter(q,clk,rst,up);. Synchronous counters can also be implemented with hardware finite state machines, which are more complex but allow for smoother, more stable transitions. If up/down = 1, then the circuit should behave as an up counter. In binary mode, it is an 8 bit binary counter. This page of VHDL source code section covers 4 Bit Binary Asynchronous Reset Counter VHDL Code. It counts up by one for each clock pulse. Low Voltage Operation of a 16-bit Counter in 32 nm asynchronous counter, a single d-type flip-flop with its J (data) I wrote 16-bit counter VHDL code and used Mentor Graphics' ModelSim to check the correctness of the function. I am going to design a N-bit ring counter in vhdl. zip - Zip file of all files from this example. The VHDL Cookbook First Edition Peter J. Counter Classification. VHDL Code for 4-Bit Aynchronous Accumulator. If there is no matching number for count in the case statement, then the default pattern is displayed which is all the LEDs off as shown in this line of code: when others => LED <= not "00000000"; Every case statement in VHDL must have a default value using the VHDL others keyword. Verilog code for 16-bit. pdf: 162: 74162 synchronous 4-bit decade counter with synchronous clear: 74162. An up/down counter is written in VHDL and implemented on a CPLD. The 3 bit MOD-8 asynchronous counter consists of 3 JK flipl flops. You will then modify your button debounce timer to include a stretch timer. If you define a two bit counter, it will wrap around automatically from 3 to 0 without the need of writing special logic for that. This page of Verilog source code section covers 4 Bit Binary Synchronous Reset Counter Verilog Code. By attaching a clock divider to the input clock, we can drive the 16 bit counter at 10 Hz (ten times per second). Let's take a look at implementing the VHDL code for synchronous counters using behavioral architecture. Design and implementation of 3 bit Down Synchronous Counter using master slave JK flip-flop IC 7476 11. std_logic_1164. The MOD of the ripple counter or asynchronous counter is 2 n if n flip-flops are used. Lots of sample VHDL code, from very simple, through I/O, to complex Hamburg VHDL Archive (the best set of links I have seen!) RASSP Project VHDL Tools VHDL Organization Home Page gnu GPL VHDL for Linux, under development More information on Exploration/VHDL from FTL Systems. Synchronous Decade Counters; Asynchronous Up-Down Counters; Synchronous Up-Down Counters; For better understanding of this type of counters, here we are discussing some of the counters. Sign up to get notified when this product is back in stock. 2 VHDL Code for a 4-bit Up for Mealy-Type State Machines 9-41 9. This behavior earns the counter circuit the name of ripple counter, or asynchronous counter. From Logo to Python in Two Decades. A counter is a common component in VHDL design. 2 Digit Up Down Counter Circuit Principle. Just write an 18-bit AND in your Verilog or VHDL code… If circuit has special structures for wide logic, synthesizer likely will use it (carry/cascade logic in an FPGA is an example). The input carry bit to the 8-bit adder is always set to 1 and the constant propogated. What is lock out condition? How lock out condition avoided?. Write and check the VHDL code for this circuit. Clock pulses are fed into the CK input of FF0 whose output, Q 0 provides the 2 0 output for FF1 after one CK pulse. In this diagram, "start" is an input which tells the system to start the. Verilog code for a 4-bit signed up counter with an asynchronous reset. 4 bit multiplier vhdl code behavioral 4 bit multiplier vhdl code behavioral. Write VHDL code for the following counters i) 4 bit asynchronous up counter ii) 4 bit synchronous up counter iii) 4 bit synchronous up/down counter with a control input up/down. Similarly, a counter having n flip-flops can have a maximum of 2 to the power n states. The asynchronous CLR, when High, overrides all other inputs and sets the Q output Low. The clock inputs. Figure 9--38 Two cascaded counters (all J and K inputs are HIGH). Last time, several 4-bit counters including up counter, down counter and up-down counter are implemented in Verilog. I am going to design a N-bit ring counter in vhdl. Presettable Binary Counter 1. For example, of a 3-bit counter, the values that can be addressed are. The 3-bit ripple counter used in the circuit above has eight different states, each one of which represents a count value. For example, rule VER_1_3_2_1 is described in the STARC documentation for Verilog Design Style Guide, section 1 (basic design constraint), subsection 1. std logic unsigned. This page of VHDL source code section covers 4 Bit Binary Asynchronous Reset Counter VHDL Code. Low Voltage Operation of a 16-bit Counter in 32 nm asynchronous counter, a single d-type flip-flop with its J (data) I wrote 16-bit counter VHDL code and used Mentor Graphics' ModelSim to check the correctness of the function. All J and K inputs are connected to Logic 1. Asynchronous Truncated Counter and Decade Counter. vhdl code for 4 bit synchronous counter using jk flipflop on December 24, 2012 Get link; Facebook; Twitter; Pinterest; Email; Other Apps; code for jk ff-- CODE: ORG 0000H MOV TMOD,#01H UP:SETB P3. 1i 3/1/2008 - 3 - • The rising_edge() is a system-defined function that is used in the if statement to indicate that changes in the circuit output can occur only on the rising edge of the CLK input. 5 Shift Register with Synchronous Parallel Load - Behavioral Model166 13. Notice that in creating a 4-bit counter, you have incidentally created a 1-bit, 2-bit, and 3-bit counter along the way. module counter (clk, clr, q); input. Kevin Barnette & Eric Hamke Lab 7 Module A – One Hot Counter • Create a oneHot project. The exterior clock is connected to the clock i/p of the FF0 (first flip-flop. Describe the circuit in synthesizable VHDL. 3-bit − hence three FFs are required. For VHDL, the corresponding rule label is VHD_1_3_2_1. verilog code for ASYNCHRONOUS COUNTER and Testbench; 8 BIT ALU(vhdl) FREQUENCY DIVIDER USING PLL(vhdl) 4 BIT SLICED PROCESSOR (vhdl) IMPLEMENTATION OF ELEVATOR CONTROLLER; Microprocessor and Controllers. Synchronous Counter Timing Diagram In the above image, clock input across flip-flops and the output timing diagram is shown. Write VHDL code for johnson counter 3. • Use the 4-bit counter and the resistor. VHDL PaceMaker is no longer sold as a product, but is still available as a free download. Edit, save, simulate, synthesize SystemVerilog, Verilog, VHDL and other HDLs from your web browser. Design of MOD-6 Counter using Behavior Modeling Style (VHDL Code). synchronous up down counter vhdl code and test bench; up counter with preload vhdl code and test bench; d flipflop with setup/hold violation, reset recove d flipflop with asynchronous reset enable and load 4 bit adder/substractor using full adder; 4 bit magnitude comparator vhdl code; Introduction to VHDL. STD_LOGIC_UNSIGNED. The use of IEEE. hello mam, i want code of 3 bit up/down synchronous counter in verilog. 3 Building a free-running downcounter 2. vhd to identify your VHDL code. Asynchronous parallel load capability permits the counter to be preset to any desired value. all; A statistical comparison of binary weighted and R 2R 4 Bit DAC; Asynchronous Device for Serial Data Transmission and Reception for android data transmission;. Write VHDL code for 3 bit up counter. I will use a counter as example for this chapter. if load = '0' then output <= "1111"; elsif. Every VHDL counter is a modulo counter. Follow via messages;. It uses polynomials (which is the math behind the LFSR) to create the maximum possible LFSR length for each bit width. It hads a 4 line input (A) a 10Hz CLK input a load input which is asynchronous a UP/Down (Down is Not down) and is synchronous a Reset input which is asynchronous a 2 line setect input line (x) a 2 line setect input line (y) a 4 line output (count) a one line output called (xeq Y) Does anyone know the code. IO Pins Description C Positive-Edge Clock CLR Asynchronous Clear (active High) CE Clock Enable Q[3:0] Data Output VHDL Code Following is the VHDL code for a 4-bit unsigned up counter with asynchronous clear and clock enable. The machine was coded using Binary, Gray, and One-Hot encoding. all; use ieee. It is simple modification of the UP counter. A 2-bit asynchronous counter, which is constructed by two T flip-flops, is shown in the following logic diagram: Now we implement this circuit in the board, such that it will count every second, use push button 2 to clear (reset), and display D1 and D0 on LED digit 1 and digit 2 respectively. Counter 2-bit: The VHDL source code can be found here: Count2bit_VHDL. synchronous 4-bit decade counter with asynchronous clear: 74LS160A. Experiments with different FSM VHDL codes In this section, an example of a finite state machine is synthesized using Xilinx Foundation 2. Setting Up the. 2 Asynchronous Operation 10. Digital Logic And Microprocessor Design With Vhdl:0534465935:HWANG VHDL Code for a D Flip-Flop with Enable and Asynchronous Set and Clear BCD Up-Down Counter VHDL for General-Purpose Microprocessors CS/EE 260. counter circuit will very quickly ripple from 0111 to 0110 to 0100 to 0000 to 1000, or from 7 to 6 to 4 to 0 and then to 8. 5 — 13 August 2019 Product data sheet 1. / VHDL: Counter with Asynchronous Reset. Please note that these codes are only for your reference, NOT 4-bit Up Counter with Enable and Asynchronous Reset CS/EE120A VHDL Lab Programming Reference. This page of VHDL source code section covers 4 Bit Binary Asynchronous Reset Counter VHDL Code. D 68000 soft IP core is binary-compatible with the industry standard 68000 32-bit microprocessor. Counter with Asynchronous Reset Top-Level Diagram. Hey there people, I am just working on this lab. If you can't use the extra register, you could just hardcode the 2ms out of 16ms value and trigger when the bit 3 gets set the first time (third bit set is 8, 8/64 == 2/16). Any hints how it is going to be represented. Four Bit Asynchronous Up Counter. We used VHDL to build a 24 bit counter with two inputs--Clock and Reset--and 8 outputs to represent the time in tens of milliseconds. Asynchronous FIFOs and DRAMs in particular. std_logic_1164. themegallery. all; entity counter is port(C, ALOAD : in std_logic;. Synthesize your code using Xilinx Vivado. 3-bit binary up/down ripple counter. VHDL Example: A Four Bit Up-counter Resetn: Reset input E: enable input In the architecture body the flip-flops in the counter are re presented by the signal na med Count If E=1, the count is incremented If E=0, the code explicitly assig ns Count<=Count The O outputs are assigned the values of Count at the en d fo the code. Here is the code for a 3 bit Synchronous counter. 32-bit counters. all; A statistical comparison of binary weighted and R 2R 4 Bit DAC; Asynchronous Device for Serial Data Transmission and Reception for android data transmission;. Verilog code for a 4-bit signed up counter with an asynchronous reset and a modulo maximum. Reset is active high and enable is also active high. DIGITAL LOGIC DESIGN VHDL Coding for FPGAs Unit 6 FINITE STATE MACHINES (FSMs) Count: 00 →01 →10 →10 →00 … 2-bit counter resetn clock 2 Q Q = 0 S1 Q = 1 Q = 3 Q = 2 S2 S4 S3 resetn = '0' Custom datatype definition: 'state' VHDL code: BCD counter. all is also required before the entity, like: library IEEE; use IEEE. 4-bit Asynchronous up counter using JK-FF (Structural model) Circuit Diagram for 4-bit Asynchronous up counter using JK-FF : Verilog Code for jkff: (Behavioural model) module jkf Half Adder and Full Adder (Dataflow Modeling). Counter Classification. 4 and later sections to make them more practically useful. will u pls help me if not give me some idea how to write its code in verilog. Verilog code for 16-bit. The clock divider is implemented as a loadable binary counter. 2 Synchronous 8 bit up counter This Synchronous up counter counts from 0 to 255, has 8 E-Xor gate, a 8 AND gates and, 8 Positive edge triggered D flip-flop’s. In a counter, the destination and first operand is a signal or variable and the other operand is a constant equal to 1: 4-bit Unsigned Up Accumulator with Asynchronous Clear Data Input. 4 bit DOWN counter will count numbers from 15 to 0, downwards. Using VHDL, build a 24 bit counter with two inputs--Clock and Reset--and 8 ouputs--time in tens of ms. The task is to write a VHDL module that implements a 4 bit counter that can count up and down. we can find out by considering number of bits mentioned in question. This is a simple explanation of VHDL code for 3 bit asynchronous counter using jk flip-flop in Vivado 2016. (5) 2> Explain the working of a 3-bit asynchronous down counter? (6) 3> What is the clock frequency in mod-8 counter, i) If the period of the waveform at C(which is MSB) is 24microsec? ii) If the period of the waveform at A(which is LSB) is 18microsec? (2) 4> Explain the working of a 3-bit asynchronous up-counter along with truth table and. VHDL PaceMaker is no longer sold as a product, but is still available as a free download. 10 Registers 7. std_logic_unsigned. 4-Bit BCD Up Counter with Clock Enable. Example 1-1: A 4-bit asynchronous binary counter is shown in Fig1-5(a). VHDL EXERCISES, 2010 COUNTERS SHIFTERS RAMs STATE MACHINE DELAY LINES 1. The VHDL while loop as well as VHDL generic are also demonstrated. If an asynchronous reset approach had be used,. From Wikibooks, open books for an open world VHDL for FPGA Design. How can we change the code to get this to occur? So here's the code for shift register. Design of 3 : 8 Decoder Using When - Else Statement (Data Flow Modeling Style)- Output Waveform : 3 : 8 Decoder VHDL Code- -- Design of 4 to 1 Multiplexer using if-else statement (VHDL Code). For example, bit 1 toggles when bit 0 is logic high; bit 2 toggles when both bit 1 and bit 0 are logic high; bit 3 toggles when bit 2, bit 1 and bit 0 are all high; and so on. This page contains VHDL tutorial, VHDL Syntax, VHDL Quick Reference, modelling memory and FSM, Writing Testbenches in VHDL, Lot of VHDL Examples and VHDL in One Day Tutorial. VHDL Code for 4-Bit Binary Up Counter January 10, 2018 February 13, 2014 by shahul akthar The clock inputs of all the flip-flops are connected together and are triggered by the input pulses. Setting Up the. The first part of this task is to build a counter with asynchronous reset. What this means is you can connect blocks of counters to build larger counter. And two outputs which are either a 3 or 5-bit bus and a terminal counter which is 1 when all bits are 111 or 11111. The total propagation delay (tp(tot)) is _____. Eight-bit register with enable and asynchronous reset 342 15. VHDL code to simulate 4-bit Binary Counter by Software Product Description; Reviews (0) Product Description. std_logic_1164. For example, in a 4-register counter, with initial register values of 1100, the repeating pattern is: 1100, 0110, 0011, 1001, 1100, so on. Circuit Diagram for 4-bit Synchronous up counter using T-FF : Verilog code for tff: (Behavioural model) module tff(t, 4-Bit Array Multiplier using structural Modeling Verilog Code for Basic Logic Gates in Dataflow Modeling. Vhdl program for a 3 bit ripple counter using 3-bit counters using D flip-flops can be designed in the same way those using JK flip-flops. Posts about verilog code for ASYNCHRONOUS COUNTER and Testbench written by kishorechurchil. The data on the D input is loaded into the flip-flop when CLR is Low on the 0 to 1 clock transition. A 5-bit asynchronous binary counter is made up of five flip-flops, each with a 12 ns propagation delay. Asynchronous Truncated Counter and Decade Counter. because i had design the ckt but i don't know how to write code for this ckt. When the RXF# flag is low, this indicates there is still unread data in the internal receive buffer. An 'N' bit Asynchronous binary down counter consists of 'N' T flip-flops. This design has the following features: 1] Negative edge-triggered. library ieee; use ieee. It may or may not have enable signal. Now look at this code in Verilog. Components described by behavioral source code should provide for the following functions: 1. Figure 9--4 Propagation delays in a 3-bit asynchronous Figure 9--35 Example 9-6 - State diagram for a 3-bit up/down Gray code counter. 3 4 Bit Asynchronous Binary Counter The following is a 4-bit asynchronous binary counter and its timing diagram for one cycle. 2 LCALL DELAY SJMP UP. Synchronous Counter Timing Diagram In the above image, clock input across flip-flops and the output timing diagram is shown. 2 A Modulo-100 BCD up counter. module counter (clk, clr, q); input. 3 Building a free-running downcounter 2. 8-Bit Simple Up Counter 8-Bit Simple Up Counter. The circuit is special type of shift register where the complement output of the last flipflop is fed back to the input of first flipflop. 4-bit Unsigned Up Counter with Asynchronous Clear The following table shows pin definitions for a 4-bit unsigned up counter with asynchronous clear. Assignment 8 : Ripple up and down counter using IC 7476. Verilog code for a 4-bit unsigned up/down counter with an asynchronous clear. 16 bit counter and 10 Hz clock divider. Alternative Four-bit "Up" Counter One way we could expand the capabilities of either of these two counter circuits is to regard the Q' outputs as another set of four binary bits. Asynchronous Truncated Counter and Decade Counter. Asynchronous Counters. 4 bit full adder verilog code. An 'N' bit Asynchronous binary down counter consists of 'N' T flip-flops. Please note that these codes are only for your reference, NOT 4-bit Up Counter with Enable and Asynchronous Reset CS/EE120A VHDL Lab Programming Reference. all is also required before the entity, like: library IEEE; use IEEE. I need it to be Up'/Down = 0 then the circuit should behave as an up counter. Let’s examine the four-bit binary counting sequence again, and see if there are any other patterns that predict the toggling of a bit. XST User Guide iii About This Manual This manual describes Xilinx Synthesis Technology (XST) support for HDL languages, Xilinx devices, and constraints for the ISE software. This page of VHDL source code section covers 4 Bit Binary Asynchronous Reset Counter VHDL Code. Output of FF0 drives FF1 which then drives the FF2 flip flop. Digital System Design with FPGA: Implementation Using Verilog and VHDL, 1st Edition by Cem Unsalan and Bora Tar (9781259837906) Preview the textbook, purchase or get a FREE instructor-only desk copy. We are excited to share our project with you! This was a final project for course CPE 133 (Digital Design) at Cal Poly, SLO in Fall 2016. web; books; video; audio; software; images; Toggle navigation. Figure 1 3-bit decimal counter behavior. all; entity counter is port(C, CLR : in std_logic; Q : out std_logic_vector(3 downto 0)); end counter;. 3-bit synchronous counter 3-bit synchronous counter amisophie (TechnicalUser) (OP) 19 May 06 23:44. Bit is forwarded or shifted on each clock cycle. You might have a good reason for asynchronous reset, but if not, synchronous reset is a better habit. VHDL code for 4-bit binary Up-Counter. Q1 and Q2 depends upon Q0 and Q1 resp. Answer Save. The Mod 11 up counter will. The 3 bit MOD-8 asynchronous counter consists of 3 JK flipl flops. In SpinalHDL, a VHDL entity and architecture are both defined inside a Component. An 'N' bit Asynchronous binary down counter consists of 'N' T flip-flops. The CLK signal can be any signal you want and will increment the value of the counter on the positive edge of a pulse, RST is the negative edge reset signal which will reset the counter to 0 or any number of your choosing also be sure to change the. Four bit up counter is designed as a separate module. An n-bit counter whose modulus is less than the maximum possible is called a truncated sequence counter, such as mod 3 (n = 2), mod 12 (n = 4). 3bit_counter. Here all inputs (D 0 , D 1 and D 2 ) are made high. What is lock out condition? How lock out condition avoided?. Parameterized counter megafunction. In asynchronous counter, a clock pulse drives FF0. You must be logged in to read the answer. (b) Parallel Load an 8, and then count up four more pulses. 13 Listing 1: VHDL testbench code for the circuit shown in Fig. VHDL 3-bit u/d counter. A 4-bit BCD-counter built with JK-flipflops. all; use ieee. Consider a 4-bit asynchronous counter; block diagram using flip-flops is as follows. Building an 18-Bit AND This is one way… Synthesizers are good at building structures like this from lower-level building blocks. verilog code for ASYNCHRONOUS COUNTER and Testbench; 8 BIT ALU(vhdl) FREQUENCY DIVIDER USING PLL(vhdl) 4 BIT SLICED PROCESSOR (vhdl) IMPLEMENTATION OF ELEVATOR CONTROLLER; Microprocessor and Controllers. implementing two UP/DOWN-counting eight-bit binary counters with asynchronous RESET input, shown in Figure 2. The frequency divider is a simple component whose objective is to reduce the input frequency. An Asynchronous counter can have 2 n-1 possible counting states e. The output is just the 4 bit number Countout the counter is currently on. VHDL Reference Manual 2-1 2. ARM assembly code to find number of odd numbers in an array ARM Assembly code to find number of even numbers in an array 8051 Program to add two 16 bit Numbers (AT89C51) Microcontroller. Follow via messages;. If the counter is equal to four, end the algorithm otherwise go to step 3. Sweet and short VHDL reference. 4-bit Synchronous up counter using T-FF (Structural model) Circuit Diagram for 4-bit Synchronous up counter using T-FF : Verilog code for tff: (Behavioural model) module tff(t, 4-Bit Array Multiplier using structural Modeling. Last time, several 4-bit counters including up counter, down counter and up-down counter are implemented in Verilog. (b) Parallel Load an 8, and then count up four more pulses. write VHDL code for a 3-bit binary counter that counts down from 5 to 0 repeatedly. VHDL: Down Counter. pdf: 162: 74162 synchronous 4-bit decade counter with synchronous clear: 74162. std_logic_1164. General description The 74HC191 is an asynchronously presettable 4-bit binary up/down counter. This is a simple explanation of VHDL code for 3 bit asynchronous counter using jk flip-flop in Vivado 2016. all; entity counter is port(C, ALOAD : in std_logic;. 17:39 naresh. Write VHDL code for 3 bit up counter. VHDL Code For 3-bit Gray Code Counter October (1) July (2) March (1) January (1) 2016 (4) December (4) Simple theme. It should include a control input called CNTRL. / VHDL: Counter with Asynchronous Reset. Play Arcade, Card, Dice & RPG Games On Facebook. VHDL and Verilog Codes Saturday, 13 July 2013. VHDL Code For 4-bit Serial In Parallel Out (SIPO) Shift Register. Four different VHDL up/down counters are created in this tutorial: Up/down counter that counts up to a maximum value and then wraps around to 0. VHDL Reference. Whereas for the up-down counter, you can use multiplexers as switches as we saw in the design of the 3-bit synchronous up-down counter. Write VHDL code for 3 bit up counter. 3) Modified VHDL code without asynchronous reset or without auxiliary bit pinout. But it is also possible to use the basic asynchronous counter configuration to construct special counters with counting states less than their maximum output number. The subtractor uses 2's complement representation for the minuend. VHDL Retrospective zVHDL is an IEEE and ANSI standard for describing digital systems zCreated in 1981 for the DoD VHSIC program – First version developed by IBM, TI, and Intermetric – First release in 1985 – Standardized in 1987 and revised several times thereafter zStandard 1076, 1076. Alternative Four-bit “Up” Counter One way we could expand the capabilities of either of these two counter circuits is to regard the Q’ outputs as another set of four binary bits. If we examine the pulse diagram for such a circuit, we see that the Q' outputs generate a down -counting sequence, while the Q outputs generate an up -counting. It counts up or down depending on the status of the control signals UP and DOWN. The concepts of test suite and testbench will thus have to be refined in numerous ways in 5. 6 bit bcd code Here is verilog code for 16 bit bcd up counter translate this to VHDL! Hope this helps!. Vhdl program for a 3 bit ripple counter using 3-bit counters using D flip-flops can be designed in the same way those using JK flip-flops. Structural Verilog code for top-level component. Synchronous modulo-2 N and modulo -M counters are studied in this section, while their asynchronous counterparts are seen in the next. i am only allowed to use AND/NAND gates and the D Flipflop should work with a falling edge. This is a simple counter without reset or load options. This example is a 4-bit down counter with a synchronous set. The circuit is special type of shift register where the complement output of the last flipflop is fed back to the input of first flipflop. This page of VHDL source code section covers 4 Bit Binary Asynchronous Reset Counter VHDL Code. The block diagram of 3-bit Asynchronous binary down counter is shown in the following figure. Write VHDL code for ring counter 2. It has asynchronous clear which is used to stop the counter. Q1 and Q2 depends upon Q0 and Q1 resp. 5 Synchronous BCD Counter 7. To generate the test bench for the simulation of BCD Counter, we need a clock, whose VHDL code is given below. Objectives After completing this lab, you will be able to: Model various types of registers. An Asynchronous counter can have 2 n-1 possible counting states e. Lab Supplies • DE2 Board • Simon Game Box Lab Videos • Counters Files Needed • Counters. The use of IEEE. VHDL Retrospective zVHDL is an IEEE and ANSI standard for describing digital systems zCreated in 1981 for the DoD VHSIC program – First version developed by IBM, TI, and Intermetric – First release in 1985 – Standardized in 1987 and revised several times thereafter zStandard 1076, 1076. 4 Counter as a Sequential Circuit 10. Let’s examine the four-bit binary counting sequence again, and see if there are any other patterns that predict the toggling of a bit. General description The 74HC191 is an asynchronously presettable 4-bit binary up/down counter. Here's the D Flip Flop code (which was tested and works):. Sign up to get notified when this product is back in stock. Have you considered how you might sample data with an FPGA? Think about data coming into your FPGA. because i had design the ckt but i don't know how to write code for this ckt. 3 4 Bit Asynchronous Binary Counter The following is a 4-bit asynchronous binary counter and its timing diagram for one cycle. VHDL code for 4-bit binary Up-Counter. VHDL Code For 3-bit Gray Code Counter October (1) July (2) March (1) January (1) 2016 (4) December (4) Simple theme. The 3 bit MOD-8 asynchronous counter consists of 3 JK flipl flops. The counter should also have an asynchronous active-low preset signal PreN that sets all flip-flops to 1. General description The 74HC191 is an asynchronously presettable 4-bit binary up/down counter. 1 Synchronous Counter 10. For example, in a 4-register counter, with initial register values of 1100, the repeating pattern is: 1100, 0110, 0011, 1001, 1100, so on. VHDL Example: A Four Bit Up-counter Resetn: Reset input E: enable input In the architecture body the flip-flops in the counter are re presented by the signal na med Count If E=1, the count is incremented If E=0, the code explicitly assig ns Count<=Count The O outputs are assigned the values of Count at the en d fo the code. VLSI Design & Implementation of AHB Master/Slave using FPGA with Verilog/VHDL code. The name ripple counter is because the clock signal ripples its way from the first stage of Flip-flops to the last stage. 4 bit UP/DOWN Counter: //Verilog module for UpDown counter //When Up mode is selected, counter counts from 0 to 15 and then again from 0 to 15. The 4 bit up counter shown in below diagram is designed by using JK flip flop. The module has 3 inputs - Clk, reset which is active high and a UpOrDown mode input. Comment By: masterdum On: May 28, 2007 3:47:04 PM. The number of states that a counter owns is known as its mod (modulo) number. vhd to identify your VHDL code. ALL; use ieee. I will use a counter as example for this chapter.