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Vhdl Code For Adc

ADC converts analog signal to digital data format.The ADC VHDL code for receiver part is mentioned below in which 12 bits are converted to16 bits with four leading zeroes for FPGA to read the digital data from ADC.

vhdl code for adc

The figure-2 depcits ADC DAC interface pin diagram for both receive and transmit section.DAC VHDL code for transmit side can also be coded similar to ADC VHDL code mentioned belowwith slight modifications.

In ADC FPGA interface, CS is pulled low and then four zeroes are being transmitted which isfollowed by 12 bits. The 12 bit represents voltage acquired by the ADC.MSB is the first to be clocked. ADC FPGA VHDL/VERILOG code for the same can be easily written.

In DAC FPGA interface, SYNC is pulled HIGH and then 16 bits are being written.First 2 bits are zeroes, next 2 bits are configuration bits and rest 12 bits are actualinformation to be converted to analog format for transmission.DAC FPGA VHDL/VERILOG code for the same can be easily written.

It depends on your requirements, I mean if you need fast ADC, maybe you should use parallel interface, if your sampling rate is slow (about up to 3 MHz) you can use a serial ADC. You can also take a look at this post:

The code has been written as read samples from the variable POT on the CPLD/ FPGA project Board and compare with reference (Vdd/Vref) voltage. Finally the equivalent Binary values are generated with help of Vref. The output of ADC would be 12 bit value which is shown on the 12 LEDs. Here the jumper has been used to select the internal &external analog input. Among the two channels one channel for POT analog input and another one for Temperature sensor.

The VHDL code presented in this model will enable you to see how to create behavioural ADC models of a particular accuracy. The example we present is for an 8-bit ADC, but you can easily modify the digital output wordlength for any desired accuracy of ADC.

For example, the default value specified in the code is spi_clk_div = 3. This is arrived at because the most common Digilent development kit at the time of this writing, the Basys3, has a system clock of 100 MHz. 100/40 = 2.5, rounded up is 3.

Below you can see my code. I am using an ODDR to forward my systemclock (SYSCLK) to the ADCs SCLK(SCLK_ADC) inputand connected them properly in the top level domain. I can't get the ADC to output CMOS signals. I think my fault is somewhere in the ADC entity.

However while compiling Quartus always removes all of my code. So in the end it pulls the LED's to GND and neither uses the ADC or the PLL. If anyone has an idea I would be really thankfull if you could tell me what exaclty im doing wrong.

In VHDL (and basically in all hardware description languages), you have to keep in mind that your code must be synthetizable: it has to describe hardware components available in your programmable component. This is not the case in your process.

Are you asking if we have sample VHDL code available for the Spartan 6 development platform? We do not have that available. We just supply the bridge cards at this time so that you can connect the TI ADC and DAC EVMs to the development platform adn begin developing your system. We do not have seed code for these platforms.

I am developing RF sampler using ADS5463EVM and I am using DE-2 115 Altera FPGA board. I wanted to get VHDL code for data communication via ADC-HSMC(Altera) header adapter card as suggested in the design kits and evaluation module.

The TSW1400 capture card uses an Altera FPGA to capture data from the ADS5463 EVM as well as many others, and the Altera Quartus project files are available for download from the TSW1400 page at =tsw1400&tisearch=Search-EN-Everything under the Software section. Our firmware source code is in Verilog, however. Not VHDL.

Also, there is a TI Design available -00069 that covers how to implement a typical LVDS interface to our ADCs and DACs using the ADS4249 as the ADC rather than the ADS5463, but the source code could be adapted to the LVDS formats used by other ADCs.

I have a question related to continuous averaging of ADCs value. The approach that I used is continuous averaging of example 256 samples. The ''adc_a_out'' value(shown in the code below) that I receive on my GUI increments slowly. As an example, if I am expecting value 100mA, My GUI shows 4mA, 8mA, 15mA,...... and then finally after 2 minutes I get stable 100mA value. I want to see the 100mA directly on my GUI from 'adc_a_out' instead of increment values and stabilizing after sometime. Another question is that, Can I somehow make this process fast so that I don't have to wait for 3 minutes for receiving stable 100 mA from adc_a_out. The clock 'clk' in the digital design below is 20 MHz. The clock for receiving ADC values on the FPGA board is 15 KHz.

The example below shows the complete code for a moving average calculator. My suggestion is that you study it until you understand it. Then, try to use it in your design. Finally, and only after you have a basic circuit working, you could change it to satisfy your design constraints (data width, number of samples, range of integers, use of signed vs. integer, etc.)

This note provides a VHDL implementation of the FPGA ADC driver. However, automated HDL code generation tools such as MATLAB HDL Coder or Xilinx System Generator can be used to create FPGA peripherals as shown on the custom FPGA PWM page.

In this article, we use Model-Based Design with MATLAB and Simulink to design a sigma-delta analog-to-digital converter (ADC). Beginning with a high-level behavioral model of the ADC, we elaborate the design and finally, generate synthesizable VHDL code.

Using this approach, we break down the 40-tap filter into 5 segments of 8 taps each. We generate a look-up table for each segment and combine the 5 look-up table outputs to produce the overall result. You can download the MATLAB code that we use to generate the look-up tables entries.

With the Embedded MATLAB function block we can bring MATLAB code into Simulink and then simulate the design. Embedded MATLAB can simplify modeling algorithms that are best and most easily represented using text-based modeling. In this case, the MATLAB code is quite simple (Figure 6).

MathWorks tools enable us to generate synthesizable VHDL or Verilog code for the fixed-point, multirate system that includes the filters, the Embedded MATLAB function block, and other blocks used in the digital section of the ADC design. We use Simulink HDL Coder to generate VHDL code from the first stage of the filter shown in Figure 8 and Filter Design HDL Coder to generate VHDL code from the second and third stages. Figure 9 shows part of the VHDL code that we generated from the first stage of the filter.

Simulink HDL Coder lets us generate VHDL or Verilog code for different hardware implementations of specific blocks, such as Sum, Product, and MinMax blocks. These different implementations are generally a compromise between speed and chip area. In our example, we use an optional control file to explore alternative implementations for the Sum block shown in Figure 8, using first a Cascade and later a Tree implementation.

In addition to the VHDL or Verilog code, Simulink HDL Coder can generate a cycle-accurate model that corresponds to the particular implementation choice made for the Sum block. Figure 10 shows the model generated for a Cascade implementation. Figure 11 shows the model generated for a Tree implementation. We can simulate the generated models and verify their output against the reference model.

Following VHDL code generation, we must prepare the code for hardware implementation. To do this we synthesize the VHDL code that we generated for the first stage of the filter and perform place and route for a Virtex 4 vsx25-10 FPGA using Xilinx ISE software tools. The timing analysis shows that we can run the design at a clock rate of 210 MHz.

In this article, we used Model-Based Design and MathWorks tools to create a high-level, executable behavioral model of a sigma-delta ADC. We elaborated on the behavioral model to prepare it for hardware implementation on an FPGA. We continuously verified the output of our models throughout the process. This approach enabled us to uncover a discrepancy in the design that could have caused performance problems if left undetected. We used Simulink HDL Coder to generate HDL code from the model and incorporated MATLAB code into the Simulink models using the Embedded MATLAB function block. An executable model created using MATLAB and Simulink is the cornerstone of this design approach.

From the above code, the Xilinx ISE environment makes is simple to build the basic framework for the testbench code. To start the process, select "New Source" from the menu items under "Project". This launches the "New Source Wizard". From within the Wizard select "VHDL Test Bench" and enter the name of the new module (click 'Next' to continue). The "New Source Wizard" then allows you to select a source to associate to the new source (in this case 'acpeng' from the above VHDL code), then click on 'Next'. The Wizard then creates the necessary framework for a test bench module (see below).

The framework above includes much of the code necessary for our test bench. It includes a component declaration section (lines 19-38), Input signal declarations and initializations (lines 41-48), Output declarations (lines 50-59) and the test component instantiation (lines 67-85). The framework also contains some canned processes for our two clock (Mclk - lines 87-94 and Sclk - lines 96-102, plus defines for clock rates - lines 62-63) and a stub version of a stimulus process (stim_proc:process - lines 105-118), which will be used to create the necessary stimulus statements to thoroughly test our design.

Looking over the traces so far, there are a couple of things to note: 1) clock pulses on the Sclk line are being passed through the device to the Eng_Sck line (no problem here as both ADC_CS and nvSRAM_CS are held high), 2) all data on the SDI line is being passed through to the Eng_So line. Neither of these are real issues. The VHDL code could have suppressed the Eng_Sck and Eng_So signals during communications to the SPI peripheral latch within the device, but it would have added complexity to the design and may have increased the use of resources in the CPLD (it is always nice to have a few spare resources in case you need to make changes in the future). Another note worthy thing is occurring right before we are entering the 'no select' state on the CS lines, at 2.25us the SDO line goes high (right before it goes back into tri-state). While the device is in the internal SPI peripheral latch state (CS = '10'), the SDO line is constantly driven with the Run flag state. As we had just finished sending a Run command to the part, we are seeing the effect of that command, which is now causing the SDO line to go high. This is showing us that the device has in fact recognized our command, and is preparing to begin a data acquisition cycle. 041b061a72


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