Shift register are the registers which are used to shift the stored bit in one or both directions. In this section, shift register is implemented which can be used for shifting data in both direction. Further it can be used as parallel to serial converter or serial to parallel converter. Verilog files required for this example are listed below,
Verilog Code For 8 Bit Parallel In Serial Out Shift 31
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Here, 4-bit count (i.e. parallel data) is generated using Mod-12 counter. This data is converted into serial data by Listing 8.5; and sent to Listing 8.6, where data is again converted into parallel and the result (i.e. count) is displayed at output as shown in Listing 8.7. The simulation results are shown in Fig. Fig. 8.5. Lastly, visual verification circuit is shown in Listing 8.8. Note that, empty_tick signal is used as clock for modMCounter (see red line in Fig. :numref:`fig_parallel_and_serial_design`), so that next count will be available when previous conversion is completed. Please read comments for further details.
The following are some of useful verilog examples.//--> Verilog code for flip-flop with a positive-edge clock Verilog code for a flip-flop with a negative-edge clock and asynchronous clear Verilog code for the flip-flop with a positive-edge clock and synchronous set Verilog code for the flip-flop with a positive-edge clock and clock enable Verilog code for a 4-bit register with a positive-edge clock, asynchronous set and clock enableVerilog code for a latch with a positive gate Verilog code for a latch with a positive gate and an asynchronous clear. Verilog code for a 4-bit latch with an inverted gate and an asynchronous preset. Verilog code for a tristate element using a combinatorial process and always block. Verilog code for a tristate element using a concurrent assignment. Verilog code for a 4-bit unsigned up counter with asynchronous clear. Verilog code for a 4-bit unsigned down counter with synchronous set. Verilog code for a 4-bit unsigned up counter with an asynchronous load from the primary input. Verilog code for a 4-bit unsigned up counter with a synchronous load with a constant. Verilog code for a 4-bit unsigned up counter with an asynchronous clear and a clock enable. Verilog code for a 4-bit unsigned up/down counter with an asynchronous clear. Verilog code for a 4-bit signed up counter with an asynchronous reset. Verilog code for a 4-bit signed up counter with an asynchronous reset and a modulo maximum. Verilog code for a 4-bit unsigned up accumulator with an asynchronous clear. Verilog code for an 8-bit shift-left register with a positive-edge clock, serial in and serial out. Verilog code for an 8-bit shift-left register with a negative-edge clock, a clock enable, a serial in and a serial out. Verilog code for an 8-bit shift-left register with a positive-edge clock, asynchronous clear, serial in and serial out. Verilog code for an 8-bit shift-left register with a positive-edge clock, a synchronous set, a serial in and a serial out. Verilog code for an 8-bit shift-left register with a positive-edge clock, a serial in and a parallel out 8-bit shift-left register with a positive-edge clock,an asynchronous parallel load, a serial in and a serial out Verilog code for an 8-bit shift-left register with a positive clock,a synchronous parallel load,a serial in and a serial out Verilog code for an 8-bit shift-left/shift-right register with a positive-edge clock, a serial in and a serial out Verilog code for a 4-to-1 1-bit MUX using an If statement. Verilog Code for a 4-to-1 1-bit MUX using a Case statement. Verilog code for a 3-to-1 1-bit MUX with a 1-bit latch. Verilog code for a 1-of-8 decoder Verilog code leads to the inference of a 1-of-8 decoder Verilog code for a 3-bit 1-of-9 Priority Encoder Verilog code for a logical shifter Verilog code for an unsigned 8-bit adder with carry in Verilog code for an unsigned 8-bit adder with carry out Verilog code for an unsigned 8-bit adder with carry in and carry out Verilog code for an unsigned 8-bit adder/subtractor Verilog code for an unsigned 8-bit greater or equal comparator Verilog code for an unsigned 8x4-bit multiplier Verilog template shows the multiplication operation placed outside the always block and the pipeline stages represented as single registers Verilog template shows the multiplication operation placed inside the always block and the pipeline stages are represented as single registers Verilog template shows the multiplication operation placed outside the always block and the pipeline stages represented as single registers Verilog template shows the multiplication operation placed inside the always block and the pipeline stages are represented as single registers Verilog template shows the multiplication operation placed outside the always block and the pipeline stages represented as shift registers Use templates to implement Multiplier Adder with 2 Register Levels on Multiplier Inputs in Verilog Verilog code for resource sharing single-port RAM in read-first mode single-port RAM in write-first mode single-port RAM in no-change mode single-port RAM with asynchronous read single-port RAM with "false" synchronous read single-port RAM with synchronous read (read through) Verilog code for a single-port block RAM with enable Verilog code for a dual-port RAM with asynchronous read Verilog code for a dual-port RAM with false synchronous read Verilog code for a dual-port RAM with synchronous read (read through) Verilog code for a dual-port RAM with enable on each port Verilog code for a ROM with registered output Verilog code for a ROM with registered address Verilog code for an FSM with a single process Verilog code for an FSM with two processes Verilog code for an FSM with three processes Top Following is the Verilog code for flip-flop with a positive-edge clock.module flop (clk, d, q);input clk, d;output q;reg q; always @(posedge clk)begin q
The 74LV165 is an 8-bit serial or parallel-in/serial-out shift register. The device features a serial data input (DS), eight parallel data inputs (D0 to D7) and two complementary serial outputs (Q7 and Q7). When the parallel load input (PL) is LOW the data from D0 to D7 is loaded into the shift register asynchronously. When PL is HIGH data enters the register serially at DS. When the clock enable input (CE) is LOW data is shifted on the LOW-to-HIGH transitions of the CP input. A HIGH on CE will disable the CP input. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess VCC.
Shift Registers are used for data storage or for the movement of data and are therefore commonly used inside calculators or computers to store data such as two binary numbers before they are added together, or to convert the data from either a serial to parallel or parallel to serial format. The individual data latches that make up a single shift register are all driven by a common clock ( Clk ) signal making them synchronous devices.
This shift register is very similar to the SIPO above, except were before the data was read directly in a parallel form from the outputs QA to QD, this time the data is allowed to flow straight through the register and out of the other end. Since there is only one output, the DATA leaves the shift register one bit at a time in a serial pattern, hence the name Serial-in to Serial-Out Shift Register or SISO.
The SISO shift register is one of the simplest of the four configurations as it has only three connections, the serial input (SI) which determines what enters the left hand flip-flop, the serial output (SO) which is taken from the output of the right hand flip-flop and the sequencing clock signal (Clk). The logic circuit diagram below shows a generalized serial-in serial-out shift register.
The Parallel-in to Serial-out shift register acts in the opposite way to the serial-in to parallel-out one above. The data is loaded into the register in a parallel format in which all the data bits enter their inputs simultaneously, to the parallel input pins PA to PD of the register. The data is then read out sequentially in the normal shift-right mode from the register at Q representing the data present at PA to PD.
This data is outputted one bit at a time on each clock cycle in a serial format. It is important to note that with this type of data register a clock pulse is not required to parallel load the register as it is already present, but four clock pulses are required to unload the data.
The final mode of operation is the Parallel-in to Parallel-out Shift Register. This type of shift register also acts as a temporary storage device or as a time delay device similar to the SISO configuration above. The data is presented in a parallel format to the parallel input pins PA to PD and then transferred together directly to their respective output pins QA to QD by the same clock pulse. Then one clock pulse loads and unloads the register. This arrangement for parallel loading and unloading is shown below.
The PIPO shift register is the simplest of the four configurations as it has only three connections, the parallel input (PI) which determines what enters the flip-flop, the parallel output (PO) and the sequencing clock signal (Clk).
Similar to the Serial-in to Serial-out shift register, this type of register also acts as a temporary storage device or as a time delay device, with the amount of time delay being varied by the frequency of the clock pulses. Also, in this type of register there are no interconnections between the individual flip-flops since no serial shifting of the data is required. 2ff7e9595c
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