New Project: Analog Acquisition board [UPDATE_1] - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: April 17, 2013, 12:02:54 am
content: Hello ppl! Hello Dave!I was following eevblog on youtube for a long time, and Dave gave me the final motivation to start to convert my knowledge in practical experience:).I have started with Arduino, but then realized it is a toy, and i would be better to learn something more useful for my future industry career:)Then i have tried Atmel µC's, but found the programming language (C) and all those register shifting a bit boring. Moreover µC are just too slow for my ambitions:DI switched to FPGA (Altera), and fell in love with its idea and VHDL:) Its damn fast, multifunctional, has lots of IO, and VHDL is just more intuitive.Ok, now to the point.My first (real) project is to interface the CCD-Camera with my DE1 Altera Board, and then show the image on Display (VGA).After that is done , i will work on patter recognition... but that comes later=)My CCD Module is this sexy beauty here:http://www.motionanalysisinc.com/specs/jai/cvm77.pdf(scored for 50 Euros on Ebay)It has lots of configuration that can be performed from my FPGA Board.But first i have to convert the analog video signal data to digital data. I decided to start a sub-project, named "analog acquisition Board"This board will contain 3 ADC : ADC08200 with 200 MSPS Max. (TI)The reference voltage for the ADC will be generated by separate DAC's: DAC5311 (TI)The heart of this board will be Altera MAXII CPLD(570 LE) : EPM570T144C5NThe CPLD will control the ADC's and DAC's , preprocess the output signal and other misc. thing. Moreover this CPLD unit will make this board to a stand alone module, that can be useed without additional FPGA Board. The Acquisition Board will be controlled via SPI-Like interface.So my goal is now to design a versatile acquisition board, witch could be later used with any kind of Dev boards(even with Arduino!).Moreover i have tried to keep the power consumption low.You can command the CPLD to switch off any unused ADC's or just to lower the sample rate. (1 MSPS=1mW)The board will also contain switchable Clock generator:LTC6905-133 (133Mhz ,66.7 Mhz or 33.3Mhz) (LT)The Voltage Regulator REG104FA-3.3 (TI) handles 12V (or lower) input voltage and provides 3.3 V for the whole module. It can handle 1 Amp.Currently my board is on its final stage:I attach the unrouted PCBI decided to place all passive components(caps and resistors) and the DAC's on the bottom layer.The Top layer contain just "high speed" things + some LEDS (D) for status indication and debugging.To make this Board even more multifunctional i will add 22 GPIO's and 2 communication ports for external controll of the CPLDSince i am a complete noob in pcb designing(this will be first PCB in my life), i am asking here for some good tips and hints about my component selection, placement and the whole idea as such:)Is it a good idea to let Altium aoutoroute the whole board, or is it better to do it manually?Moreover i am curios if someone else is interested in this small project, so maybe i will make this board available as open source?=)PSI am thinking about making a few tutorial videos about my main FPGA project(inkl. Sub Project): From choosing components to first PCB Design and finally about programming the FPGA/CPLD and showing the image an my monitor as a result of many hours of creativity:)) . Just not sure if there is enough ppl. interested in this stuff.TNX for reading

author: jmole
author_rank: Regular Contributor
timestamp: April 17, 2013, 12:15:48 am
content: There are ADCs specifically for 3-channel video capture that may be a much cheaper solution than 3 discrete 200 MSPS ADCs.Here's just one of many examples, the TVP70025I:http://www.mouser.com/ds/2/405/sles232b-127512.pdfVery ambitious project! Good luck!

author: saigai
author_rank: Contributor
timestamp: April 17, 2013, 12:24:32 am
content: I'm also using TVP7002 on a similar project. It's pretty awesome for a newbie like me - 3x ADC, clock generation and other black magic all done for me.

author: Unknown
author_rank: Unknown
timestamp: April 17, 2013, 12:30:15 am
content: Yeah, i know there is special IC for video processing.But then this board will be useful only for video processing, while my board can be used in many different application+ it has some processing power provided by CPLD;)By taking a simple IC i wouldn't learn how to design own project

author: saigai
author_rank: Contributor
timestamp: April 17, 2013, 12:37:07 am
content: Quote from: Citizen on April 17, 2013, 12:30:15 amGood enough reasons to go the hard way! All aspects of your project are very interesting to me, and I do hope to hear more about it

author: kt315
author_rank: Regular Contributor
timestamp: April 17, 2013, 12:53:41 am
content: When it come to pattern recognition, hardware solution is not exactly the first thing that comes to my mind. It is actually a huge work on it is own. There is an OpenCV project, which is currently de facto is a standard for such application.You are seriously limiting what you can do with the image later on if you start with CPLD. Just a word of caution ...I'd probably would be looking at linux boards if I wanted to do any kind of interesting image processing. But all depends on how much you want to do with it of cause.

author: Unknown
author_rank: Unknown
timestamp: April 17, 2013, 12:59:07 am
content: No no, you get me wrong:)The MAIN processing will be handled on my Altera DE1 FPGA board.The acquisition board just serve as fast AC-DC converter + preprocessing in the man project

author: Unknown
author_rank: Unknown
timestamp: April 17, 2013, 01:37:52 pm
content: No further suggestions?

author: jahonen
author_rank: Super Contributor
timestamp: April 17, 2013, 02:01:41 pm
content: How are you going to generate the line locked clock for AD-conversion of the incoming video to prevent video jittering? To perfectly match your camera resolution, you'll want a line-locked 25 MHz clock for ADC. What about the black level clamping and synchronization separator?Regards,Janne

author: Unknown
author_rank: Unknown
timestamp: April 17, 2013, 02:13:42 pm
content: My JAI CV-M77 has PixelCLK output so i can sync. ADC with Pixeldata.Moreover it has HD/VD input/output.ith it i can see when to start recording data, or i can trigger it by myself:)

author: jmole
author_rank: Regular Contributor
timestamp: April 17, 2013, 07:30:52 pm
content: Quote from: Citizen on April 17, 2013, 01:37:52 pmMy only comment is that you're embarking on a very ambitious project for your first PCB design. It sounds like you have a lot of experience otherwise, so you may be alright in this regard.I would read as much as possible about high-speed PCB layout techniques. There are tons of application notes around that will help you in this endeavor. The more you know before you start, the fewer mistakes you'll make. That said, experience is by far the best teacher.Second, I would highly recommend adding test points *everywhere*, inasmuch as you can get away with it. It can be very frustrating to debug a complex design when you can't fit your probes into the places they need to go. You'll also want to ensure that the test points dont add any reflections or impedance mismatches to your signal, data, and clock lines. One easy way is just to add an untented via of sufficient size to the traces you care about. Later, if you need to probe, you can either solder a testpoint to the via, or probe it directly with your oscilloscope.Good luck!

author: Unknown
author_rank: Unknown
timestamp: April 17, 2013, 11:14:49 pm
content: Hi.Tnx for advice.I really orgot abouzt test points at all.Furthermore have decided to read literature about high speed PCB, before routing the PCb manually.This way i will learn even more:)P.SIs 150 Mhz really high speed league?

author: jahonen
author_rank: Super Contributor
timestamp: April 18, 2013, 10:33:43 am
content: Quote from: Citizen on April 17, 2013, 11:14:49 pmLike it has been said many times on this forum, it is not the clock frequency but the edge rate of your signals. You might experience high speed signal issues regardless of the clock rate if your edge time starts to be comparable to the propagation delay of your PCB traces. Traces with uncontrollably high impedance are usually the worst offenders.Regards,Janne

author: Unknown
author_rank: Unknown
timestamp: May 20, 2013, 06:14:07 am
content: Hello There:)The project go on. I finally managed to design a PCB. It is almost finished.But because it is my first serious project and first PCB, i would like to have a feedback from experienced users here. I will attach the gerber files. Please take a look, if you don't mind:)I took 250 Mhz XO as Main Clock, and will use a devider in CPLD, to drive ADC.Instead of using VGA connector i will use a convenient BNC for each channel:)

author: Harvs
author_rank: Super Contributor
timestamp: May 20, 2013, 01:15:48 pm
content: Mate, if you want people to seriously look at your board, you need to do more than give them the gerber files.From the renders, looks like you're using altium.Just use the Smart PDF function, do it on the whole project (so it includes both schematic and PCB layers), then right click in the layer set area and create final which will include a page for each of the layer sets.Then you've got a PDF from which people can have a reasonable chance of giving feedback.

author: Unknown
author_rank: Unknown
timestamp: May 21, 2013, 06:38:38 am
content: Thanks for advice. I am new to altium. Here is the PDF File.Some people are saying that my PCB could be much smaller.Moreover they say i i have to switch to the 4-Layer PCB, with proper GND and PWR plane. That will keep size down, so the price should be about the same.Any suggestions ?