[CLOSED] AD9959 ebay board troubleshooting. - Page 1
Forum section: electronics / rf-microwave

author: MasterT
author_rank: Frequent Contributor
timestamp: August 22, 2018, 11:55:37 pm
content: Get myself a new toy, can't make it operational. Link to product:https://www.ebay.ca/itm/AD9959-Radio-Frequency-RF-Signal-Source-Generator-4-Channel-DDS-Module-DC5V/183317556697After spending a few hours on software potential bugs tracking, I resolved to make a hardware inspection. Power and clocks certainly come first, and here is a surprise. As can be seen from the picture, board has 25 MHz TXC oscillator installed. Running at 3.3V it outputs 4 Vp-p ( at least what I see on a scope, may be overshot), seems too much for 1.8V DDS core.And what worse, pin 24 is set to high, and according to DS internal oscillator is activated.Page 20, table 4.http://www.analog.com/media/en/technical-documentation/data-sheets/AD9959.pdfOriginal EVAL board from analog has a crystal, and it makes me think, that copy-paste stupid mistake happened. If external oscillator is used, pin 24 must be low, and voltage divider needs to be installed to reduce drive down to 1000 mV (max value from DS).Whats options do I have? Return board to seller? I have no idea how to do it, but cutting traces does not make me feel good.

author: Bud
author_rank: Super Contributor
timestamp: August 23, 2018, 12:19:48 am
content: This IC is priced by byADI $51 CAD in quantities >1000. The whole board is only CAD $40. Chances are it is a counterfeit IC. Your findings about the clock circuit may be another indication of it. Perhaps the Chinese clone does require 4V clock and gives no shit about pin 24.Edit: you can replace the clock oscillator with one that has a suitable amplitude.Edit: You can make a close up photo of the chip, send it to ADI and ask if they can confirm the chip is genuine. If they say it is not you can open a dispute and get a refund.

author: xaxaxa
author_rank: Regular Contributor
timestamp: August 23, 2018, 04:22:31 am
content: Quote from: Bud on August 23, 2018, 12:19:48 amADI parts prices are fairy tales and fantasy. What you see on the official website is 10x higher than what people actually pay for them. For example ad9363 costs >$100 on digikey, $80 @ 1k qty on the AD website, but in reality is worth $10 on the spot market. Another good example is the ADF4350, $12 on digikey, $0.5 in real life.

author: Bud
author_rank: Super Contributor
timestamp: August 23, 2018, 05:57:59 am
content: Real life that is price in China?I have seen counterfeit piece of shit "Cypress" USB controllers and "ADI" DDS ICs , Chinese made fakes. So no, China does not count.Show me a reputable supplier that sells AD9959 for less than ADI bulk pricing.

author: CJay
author_rank: Super Contributor
timestamp: August 23, 2018, 09:30:24 am
content: @MasterT Open an ebay case and have a dialogue with the seller, don't mess about with the board until you have permission to do so or you're sure there's no other option, if you work on it then the seller could refuse to refund/replace.As for the belief that it must be counterfeit if it's cheap, yes there are fakes but cheap does not in the vast majority of cases mean fake.I have bought genuine AD9851 parts at a fraction of their list price from an excess inventory broker who's warehouse is 15 miles from my home, I've no doubt whatosever that this market is exponentially larger and much cheaper in HK and China.I've also no doubt that the price breaks you see on AD and Digikey bear no resemblance to the prices volume manufacturers pay, 10,000 pieces is a sample order for some.

author: MasterT
author_rank: Frequent Contributor
timestamp: August 23, 2018, 12:55:48 pm
content: Quote from: Bud on August 23, 2018, 12:19:48 amGood things if it's counterfeit, I'm sure original AD IC would be dead on first switch on, having 3.3V square wave with 100 mA current capability on it's Ref-clk input .I checked what kind of clock ADF4351 board has, that I bought on ali a while ago about the same price. 1.5Vp-p for 3.3V IC, seems correct.The seller offers a replacement. I'd take a chances, still want DDS generator for my garage lab

author: AF6LJ
author_rank: Unknown
timestamp: August 24, 2018, 03:16:45 am
content: Quote from: Bud on August 23, 2018, 12:19:48 amBeat me to it.This is one of those things that I see from time to time on E-Bay that send off all kinds of alarm bells, I avoid this stuff like the plague.

author: cncjerry
author_rank: Unknown
timestamp: August 31, 2018, 04:14:44 am
content: Most of the time when you cant get these boards running it is related to the eval code being developed on either 32bit or Windows XP, not 64bit. I had a heck of a time getting a 9959 board running on anything other than windows XP. No logic behind it, just wouldn't run until I used XP.The odds of the 9959 chip being counterfeit are almost zero. Maybe the cypress chip if it has one but the 9959s unlikely. Try XP and go from there. The other issue generally is that you have to be careful to use the wall wart they supply or the correct power. Don't assume 5v or 12v or whatever. I blew a board once using 12V when 5v was spec'ed.Jerry

author: MasterT
author_rank: Frequent Contributor
timestamp: August 31, 2018, 09:28:43 am
content: Quote from: cncjerry on August 31, 2018, 04:14:44 amThere are different kind of boards, official from Analog has DDS AD9959 + supplementary uCPU , so DDS synthesizer could be interfaced and configured from PC, over USB interface. uCPU serves as an USB->to->SPI bridge.This is what, probably, you mean.But if you click a link from first message, there would be a picture of the board I've got, cheapest version w/o any bridges. Consequently, there is no USB, just raw SPI bus pin header.I'm still waiting a replacement, "ticket" is open on ebay. I'd post updates when I received one.

author: cncjerry
author_rank: Unknown
timestamp: September 01, 2018, 07:01:31 am
content: You're right, my 9959 board has a second board linked to the 9959 board with a flat cable.

author: astro10
author_rank: Newbie
timestamp: September 23, 2018, 02:12:36 pm
content: Any luck making this board work? For the price, I was planning on buying one to play around with it.

author: MasterT
author_rank: Frequent Contributor
timestamp: September 23, 2018, 03:08:36 pm
content: Quote from: astro10 on September 23, 2018, 02:12:36 pmI didn't try to repair, put it aside. I'm still waiting for replacement, they told me on ebay - they send one. Situation is quite risky for me, my ebay protection is gonna to expire on 26-09-2018, and if the seller cheats on me - and didn't do anything just pulling a time, than I lost $42. Was hoping to receive a package before this warranty on return expire...

author: metrologist
author_rank: Super Contributor
timestamp: January 09, 2019, 03:23:02 pm
content: what happened? Has anyone seen a "good" module? Are the AD9910 modules any better?

author: MasterT
author_rank: Frequent Contributor
timestamp: January 09, 2019, 03:59:01 pm
content: Quote from: metrologist on January 09, 2019, 03:23:02 pmNot me, never seen. I was not thinking right, trying to get replacement for a module, that has a flow in design. And a seller didn't actually bother to send anything second time.I break a chip in a half, completing autopsy, and 100% sure IC is a junk, out of 56 wires between a silicon and external pads I counted no more than 10.Lesson is learned.

author: OwO
author_rank: Super Contributor
timestamp: January 10, 2019, 01:05:19 pm
content: Quote from: MasterT on January 09, 2019, 03:59:01 pmTake a picture? I'm curious how you can break open a QFN and still be able to see bond wires.How are you interfacing with the board? If you are programming the registers yourself from an arduino or something then I'm 99% sure the problem is with your code. From my experience in troubleshooting designs the parts are the last thing to blame, and 9 times out of 10 the problem is the software (even board mistakes are not nearly as common as a simple one-character fuckup in your code). Add the fact that this is a pretty popular board on taobao selling at about the same price, with 83 good reviews out of 83 total reviews it's close to impossible it is a scam product (it is possible you got a dud by chance but still unlikely).

author: metrologist
author_rank: Super Contributor
timestamp: January 10, 2019, 02:23:45 pm
content: I had good luck controlling an ebay AD9850 module with an Arduino.

author: Bud
author_rank: Super Contributor
timestamp: January 10, 2019, 02:59:47 pm
content: Reviews on taobao tell me exactly nothing. Is there one saying "i have tested it in all major configurations and it worked fine"? Most of the people give reviews based on how pretty the product looks. Did they test the PLL multiplier? Did they test with an external 1GHz clock? Did they test the LPF bandwidth? Did they test amplitude control? Frequency and phase resolution? Does ouput matches specification in the datasheet?

author: OwO
author_rank: Super Contributor
timestamp: January 10, 2019, 03:45:15 pm
content: The OP's issue was he couldn't get the board working at all, or presumably no output. If you told me the board has design flaws XYZ which means it won't meet spec under conditions NNN and none of the taobao buyers caught that then I'd believe you. I'm just saying the conclusion (the chip is a nonfunctional fake) is highly improbable given there being no negative reviews out of 80 reviews. Do you think people who review products by how they look would be buying a AD9959 dev board?

author: Bud
author_rank: Super Contributor
timestamp: January 10, 2019, 04:25:48 pm
content: You may be surprised how many people buy stuff and never get to using it, myself included mostly because of long shipping times and i lose interest by the time it arrived, or my priority changed.

author: MasterT
author_rank: Frequent Contributor
timestamp: January 10, 2019, 06:22:25 pm
content: Quote from: OwO on January 10, 2019, 01:05:19 pmDidn't take any pictures.IC is a fake, it was obvious from the beginning. But I was o'k with that. The board itself is too thin and flimsy to survive traveling in the unprotected envelope.I just re-checked product link from my OP, and to my surprise ebay say "be the first to write a review".Do I need a proof, that I write a review? And a picture, or better screen shots?This conversation is leading to no where. Thread was started to get an advice from people that have hands-on experience with a module, but it turns out there is no one.And it's too late anyway.

author: metrologist
author_rank: Super Contributor
timestamp: January 10, 2019, 07:54:20 pm
content: Quote from: MasterT on January 10, 2019, 06:22:25 pmIt may be too late for your board, but I hope you are not getting offended. There are still questions and I think there was hope you could provide more information, even if just anecdotal and for others. I may still buy one and see. Maybe if I can't figure it out I can send it to someone who is more apt. and they can report.It seems whatever problem there was with the OP's board that it is not likely a systemic issue because people are far more vocal about failures, and is this the only mention of a failure of this module?

author: Bud
author_rank: Super Contributor
timestamp: February 16, 2019, 10:18:22 pm
content: Another dead Chinese dodo in this new thread:https://www.eevblog.com/forum/rf-microwave/all-you-need-to-know-about-the-chinese-ad9959-ebay-board/

author: edigi
author_rank: Regular Contributor
timestamp: February 18, 2019, 12:00:12 pm
content: Maybe I'm late to the party here but just to note that I think I have the same board (from a different seller though; from around the same time this thread started) and I could make it work (at least it could output 100 MHz and 200 MHz since in single tone mode).I did not modify the board in any way.I have no way to know if the chip is fake or original but I heavily suspect that it's original.I've used Arduino + ESP32 and controlled the 9959 via SPI.A cleaned up (from leftovers of many similar projects since I tested quite many different boards from e-bay; btw. I've got all of them - and that's not a short list- working after some time) version of the test code attached.Note: If you need more information about the board I can make photos of it since I still have it (somewhere; I'll need to dig it out) but I don't provide support related to the board/the attached code/how to use 9959 since it was just a hobby project for me, not anymore interested in 9959 usage and I'm not affiliated with anybody that has anything to do with this board (ADI, e-bay seller or designer/manufacturer of the board). Also my code is not necessarily the best example, since bit fields are compiler dependent, but I'm lazy (and prefer readability) and so far I had no problem with this.

author: Bud
author_rank: Super Contributor
timestamp: February 18, 2019, 01:57:53 pm
content: That is great that yours worked but you probably won't dispute that it worked outside of the manufacturer specification with the incorrect reference clock configuration and the clock amplitude exceeded the specs by 4 times, as well as unequal DAC shoulders loading as I pointed out in the other post above. Guarantee, if you could measure the DAC output phase noise and spurs they would be awful, because the output phase noise directly depends on the quality of the clock. None of careful RF designers, except maybe the ones from Rigol, would use the DDS chip under such conditions.

author: edigi
author_rank: Regular Contributor
timestamp: February 18, 2019, 03:41:05 pm
content: You have plenty of good points in the other thread. The biggest pain with these boards is the lack of documentation, so it's rather hard to know before it arrives what you get, how it's assumed to be used (as e.g. there are trade offs to be used at the low end and high end of the output frequency range).Related to the overdrive (not to dispute that it does not exist) how much of an issue is it? As I wrote I've tested quite many different types of boards and now I heavily suspect that many of them have similar mistake but yet all of them was working. Can it destroy the clock input of the chip? Probably not (due to the high impedance of the TCXO output). So what does it cause? Does it really impact the quality of the clock so badly? Does e.g. overdrive impact rise time negatively? Also there is no direct coupling but via loop filter (which is also messed up...).Btw. ADI 9959 documentation is also lacking here, I remembered from other documents (at least 9910, 9954) that mV p-p is specified, here it's just 1000mV...You have also a good point about impedance matching and you assume 50 Ohm load (probably from resistor, and SMA connector) but is it the way it's planned to used? How much of a necessity is it at max. 200 MHz?In short: it's very good that you've explored the board in detail (thanks for the huge work) and we can better understand now how it's supposed to be used and what mistakes the designers made. This however still does not mean that the board should totally fail generating a signal and I guess the was the issue of the OP in this thread.

author: edigi
author_rank: Regular Contributor
timestamp: February 18, 2019, 07:24:01 pm
content: A photo of my board and chip + fixed source code cleaning (previous wrong attachment removed)...

author: Bud
author_rank: Super Contributor
timestamp: February 19, 2019, 02:03:18 am
content: I replied in my thread at the below link, the OP has closed this thread, I do not want to hijack it.https://www.eevblog.com/forum/rf-microwave/all-you-need-to-know-about-the-chinese-ad9959-ebay-board/msg2210496/#msg2210496

author: edigi
author_rank: Regular Contributor
timestamp: February 19, 2019, 07:57:06 am
content: One final note (for those who have trouble with it) about how to bring life to these boards before I stop hijacking this thread.So if you carefully check my attached photo you may notice one of the leftmost pins has a yellow wire and it goes to GND.Since the board has an external power plug it may immediately raise an alarm in your head, where does this wire go then?Unfortunately it's not visible in the photo (not in the source code either) so I have to tell: a pin header abbreviated to PDC. So it's a power down control and in order not to power down the chip it has to be connected to GND (low value).I don't remember anymore if I had trouble with this particular pin but I definitely remember that in case of the overwhelming majority of many boards I had some trouble with this kind of things. So with one notable exception (9954 that had excellent documentation) I have not received any documentation whatsoever with these boards. Naturally one can match the pin headers based on the datasheet without much trouble but I've soon realized how easy is it to overlook one of these power down pins.ADI chips have excellent power control features where different parts of the chip can be powered down (DDS, DAC, etc. I'm talking generally here not about just this particular board), many have related control bits, most have pins and many of those are connected to pin headers of the various board.Since there is no schematic, one can wrongly assume (I did it initially in many cases) that probably they have some kind of pull-up/pull-down resistors so that by default they activate the chip (after all it's a kind of an evaluation board).Totally wrong. Most (if not all; I can't remember anymore) are just left floating.If you wouldn't like to waste countless hours when messing with this kind of boards this is definitely something not to forget and take special care...

author: Kalvin
author_rank: Super Contributor
timestamp: February 19, 2019, 09:06:41 am
content: Quote from: edigi on February 18, 2019, 07:24:01 pmI have the same board but haven't had time to play with it yet. Thanks for the source code!That will be most useful when trying out the board and determine whether its a lemon or not.Also, great thanks for Bud to start this thread.

author: cemelec
author_rank: Contributor
timestamp: March 02, 2019, 09:12:11 am
content: I have one of those boards (from Aliexpress) and it works fine, tried various frequencies and PLL multipliers, all OK.You probably know and have already done this, but initially I had problems until I grounded IO3 and PDC then all went well.I am using one of those "blue pill" STM32F103 boards + my own code

author: rprr
author_rank: Newbie
timestamp: July 08, 2019, 05:00:29 pm
content: @edigi -- Thank you for the code. I'm going to try to implement it via python on my Raspberry Pi.Edit to add: I was able to get one of my two boards to work. The first key was the PDC control pin to ground. Thank you.This was on a Raspberry Pi with Python. I used a Python program available on github (https://github.com/mgrau/ad9959) with a couple of minor mods.1. Changed the program to use spi.writebytes to deliver the full payload including register address + data in one shot as mentioned in the datasheet.2. I also specified the bus speed explicitly at 1MHzI have just begun playing with it. I see lots of spurs. I don't have a proper SA, so using an RTL-SDR dongle with gqrx. Will read datasheet some more.Many thanks again.