ADC Configuration

[Moris]

Hello guys,

Am a newbie here, I'm designing a DAQ system using AD7616 ADC and Zynq7000 FPGA chip.

I have tried to figure out how to start with the programming of ADC, am sorry to say that it is really difficult to me. 

I'm thinking the most important part is to program the ADC to read analog data from sensors and to transfer that to FPGA.

Not Sure if anyone have any ADC example project code that i can take reference to? 

Is there any document available in which complete detail of ADC(I know the basic theory of the ADC) is available like which parameters of the ADC are important, or with any coding example. 

Appreciate it and Thanks 

[zygot]

ADI has pretty good FPGA support for their device EVM boards, including the AD7616 and its siblings. ADI also has some good literature on a number of topics from which anyone an learn things. Nearby I've posted comments about using the AD7606 which I won't replicate here.

There are a lot of different ADC types and the datasheets for ADC devices can be difficult to parse if you aren't experienced. So, what I'm saying is that while you may find a document that is good at introducing the concepts of using ADC devices it's more likely that you will need to read quite a bit of literature on the subject if you really want to understand which converters are best for a particular application. The semiconductor industry has seen a lot of companies being bought out by larger companies and the converter market is no exception. Both ADI and Ti have good application notes to help you along. Since you've already made your choice of converter start with learning about how that one works. In my view there isn't a basic theory of ADC device, there is a basic theory for each of the ADC architectures and implementations.

 

On 3/15/2021 at 1:41 AM, Moris said:

I'm thinking the most important part is to program the ADC to read analog data from sensors and to transfer that to FPGA.

I'd disagree. The most important thing to do is start off with specifications for your DAQ system. What sampling bandwidth do you need? What kind of sensors are you wanting to connect to? What kind of post-processing does it do? How much storage do you need for sample data? What happens to the ADC data once it's been collected and processed? etc, etc. The AD7616 type of converter has applications that it is ideal for but probably isn't a good general purpose device for a general purpose DAQ system. Collecting ADC samples and storing them is probably the easiest part of your project.

I've designed my own HDL for using the AD7616 on the Nexys Video board because it has a reasonably good USB 2.0 interface available for transferring data to a PC and Digilent provides a usable API for the PC application. You can also use the FTDI D2xx driver API. This only required me to do one software application. Of course your vision for a DAQ might be different than mine.

[Moris]

Thank you so much for your valuable feedback. Actually, the DAQ system is for the Engine and I just have to take the basic sensors output and display their values on LabView. I chosen AD7616 because of it's some characteristics. You're right as I'm not experienced in ADCs I don't understand the datasheet much. That's why I posted here. 

Can you please mention me or send the link of post where you commented about the use of AD7606, may be after reading those I'll get some idea.

Thank you again.

[zygot]

4 hours ago, Moris said:

I'm not experienced in ADCs I don't understand the datasheet much.

A lot of people don't understand ADC datasheets. This is because of marketing considerations**. As I mentioned above both ADI and Ti have some pretty good material to help you sort it all out. I can't sway you toward or away from any particular ADC device because I don't know how yo will be using it. Choosing the proper ADC device and topology is something to sort out when you write the specifications for your design. If you haven't written down you objectives then I;d suggest that this is a good place to start. Define the exact sensors that you will be using, sample rate, etc. Don't confuse the sample rate Fs with the analog bandwidth of a converter. Some ADCs are DC accurate and some are not.

** Even seasoned engineers using converters can get mislead by the datasheet; I still sometimes get caught. Often, a red flag is missing specifications or topics that the datasheet ignores. The AD7606, AD7616, etc. type devices achieve really spectacular noise and accuracy numbers by doing decimation and filtering in the device. Sometimes this is good and sometimes not so good. It all depends on the application.